LabWindows/CVI
Programmer
Reference Manual
LabWindows/CVI Programmer Reference Manual
February 1998 Edition
Part Number 320685D-01
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About This Manual
Organization of This Manual...........................................................................................xiii
Conventions Used in This Manual...................................................................................xiv
Chapter 1
LabWindows/CVI Compiler
C Language Non-Conformance.......................................................................................1-2
C Library Issues...............................................................................................................1-5
Debugging Levels............................................................................................................1-8
Pointer Comparison (Non-Fatal).........................................................1-10
Pointer Subtraction (Non-Fatal)..........................................................1-10
Pointer Casting (Non-Fatal)................................................................1-10
Dynamic Memory Protection Errors .................................................................1-11
Memory Deallocation (Non-Fatal)......................................................1-11
Memory Corruption (Fatal).................................................................1-11
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Contents
Disabling Library Errors at Run-Time ............................................... 1-12
Disabling Protection for Individual Pointer........................................ 1-12
Details of User Protection................................................................................. 1-14
Function Parameters.......................................................... 1-15
Unions................................................................................................. 1-16
Stack Size ........................................................................................................................ 1-16
Chapter 2
Using a Loadable Compiled Module as an External Module ........................... 2-4
Example 1........................................................................................... 2-5
Example 2........................................................................................... 2-6
Chapter 3
Windows 95/NT Compiler/Linker Issues
Loading 32-Bit DLLs under Windows 95/NT ................................................................ 3-1
DLLs for Instrument Drivers and User Libraries.............................................. 3-2
Using The LoadExternalModule Function ....................................................... 3-2
Link Errors when Using DLL Import Libraries................................................ 3-2
DLL Path (.pth) Files Not Supported................................................................ 3-2
16-Bit DLLs Not Supported.............................................................................. 3-2
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Run State Change Callbacks in DLLs...............................................................3-2
Compatibility with External Compilers...........................................................................3-4
Bit Fields.............................................................................................3-6
Long Doubles......................................................................................3-7
Differences between LabWindows/CVI and the External Compilers...............3-7
External Compiler Versions Supported.............................................................3-8
Multithreading and the LabWindows/CVI Libraries.......................................................3-8
Using LabWindows/CVI Libraries in External Compilers..............................................3-9
Include Files for the ANSI C Library and the LabWindows/CVI
Libraries..........................................................................................................3-10
Resolving Callback References from .UIR Files ..............................................3-10
Linking to Callback Functions Not Exported from a DLL.................3-11
Microsoft Visual C/C++ .....................................................................3-16
Borland C/C++....................................................................................3-16
Watcom C/C++ ...................................................................................3-16
Symantec C/C++.................................................................................3-16
Borland Static versus Dynamic C Libraries......................................................3-17
Borland Incremental Linker ..............................................................................3-17
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Symantec C/C++............................................................................................... 3-19
Customizing an Import Library......................................................................... 3-20
Preparing Source Code for Use in a DLL......................................................... 3-21
Include File Method............................................................................ 3-22
Calling Windows SDK Functions in LabWindows/CVI................................................. 3-26
Setting Up Include Paths for LabWindows/CVI, ANSI C, and SDK Libraries.............. 3-28
Compiling in LabWindows/CVI for Linking in an External Compiler............ 3-28
Compiling in an External Compiler for Linking in an External Compiler ....... 3-28
Handling Hardware Interrupts under Windows 95/NT................................................... 3-29
Chapter 4
Windows 3.1 Compiler/Linker Issues
Using Modules Compiled by LabWindows/CVI ............................................................ 4-1
Using 32-Bit Watcom Compiled Modules under Windows 3.1...................................... 4-1
Using 32-Bit Borland or Symantec Compiled Modules under Windows 3.1 ................. 4-2
16-Bit Windows DLLs .................................................................................................... 4-3
Helpful LabWindows/CVI Options for Working with DLLs........................... 4-4
DLL Rules and Restrictions.............................................................................. 4-4
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DLL Glue Code.................................................................................................4-7
Loading a DLL That Cannot Use Glue Code Generated
at Load Time ....................................................................................4-8
If the DLL Requires a Support Module outside the DLL.....4-9
If You Pass Arrays Bigger Than 64 K to the DLL...............4-9
Pointers ..............................................................................4-18
Recognizing Windows Messages Passed from a DLL......................................4-21
Creating 16-bit DLLs with Microsoft Visual C++ 1.5......................................4-21
Creating 16-bit DLLs with Borland C++ ..........................................................4-22
Chapter 5
UNIX Compiler/Linker Issues
Calling Sun C Library Functions.....................................................................................5-1
Run State Change Callbacks Are Not Available in Executables ......................5-5
Using Externally Compiled Modules ..............................................................................5-6
Restrictions on Externally Compiled Modules..................................................5-6
Compiling Modules With External Compilers..................................................5-6
Locking Process Segments into Memory Using plock() .................................................5-7
UNIX Asynchronous Signal Handling ............................................................................5-7
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Contents
Solaris 1 ANSI C Library Implementation...................................................................... 5-8
Replacement Functions..................................................................................... 5-9
Additional Functions Not Found in Sun Solaris 1 libc ..................................... 5-9
Incompatibilities among LabWindows/CVI, Sun Solaris, and ANSI C ......................... 5-10
Chapter 6
Building Multiplatform Applications
Multiplatform Programming Guidelines......................................................................... 6-1
Library Issues.................................................................................................... 6-1
Chapter 7
Configuration Option Descriptions................................................................... 7-6
Necessary Files for Running Executable Programs ........................................................ 7-8
Necessary Files for Using DLLs Created in Windows 95/NT........................................ 7-9
Location of Files on the Target Machine for Running Executables and DLLs............... 7-9
LabWindows/CVI Run-Time Engine under Windows 95/NT ......................... 7-10
Run-Time Library DLLs .................................................................... 7-10
Low-Level Support Driver ................................................................. 7-10
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LabWindows/CVI Run-Time Engine under Windows 3.1 ...............................7-11
LabWindows/CVI Run-Time Engine under Sun Solaris ..................................7-12
Rules for Using DLL Files under Windows 95/NT ..........................................7-13
Rules for Using DLL Files under Windows 3.1................................................7-13
Rules for Loading Files Using LoadExternalModule .......................................7-14
Forcing Modules that External Modules Refer to
into Your Executable or DLL ..........................................................7-15
Using LoadExternalModule on Files in the Project............................7-15
Not in the Project .............................................................................7-16
Windows 95/NT...............................................................................7-17
under Windows 3.1 ..........................................................................7-17
Using LoadExternalModule on Source Files (.c)................................7-18
Rules for Accessing Other Files........................................................................7-19
Chapter 8
Distributing Libraries and Function Panels
How to Distribute Libraries .............................................................................................8-1
Chapter 9
Checking for Errors in LabWindows/CVI
Error Checking.................................................................................................................9-2
Data Acquisition Library...................................................................................9-4
VXI Library.......................................................................................................9-4
GPIB/GPIB 488.2 Library.................................................................................9-4
RS-232 Library..................................................................................................9-5
VISA Library.....................................................................................................9-5
IVI Library.........................................................................................................9-5
TCP Library.......................................................................................................9-6
DDE Library......................................................................................................9-6
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Contents
ActiveX Automation Library............................................................................ 9-6
X Property Library............................................................................................ 9-6
Formatting and I/O Library............................................................................... 9-6
Utility Library ................................................................................................... 9-7
ANSI C Library................................................................................................. 9-7
Appendix A
Appendix B
Glossary
Figures
Figure 7-1.
on a Target Machine........................................................................... 7-8
Tables
Table 1-1.
Table 1-2.
Table 1-3.
LabWindows/CVI Compiler Limits ....................................................... 1-1
Stack Size Ranges for LabWindows/CVI............................................... 1-16
Table 7-1.
Table 7-2.
LabWindows/CVI Run-Time Engine Files ............................................ 7-10
Windows NT Registry Entry Values for the Low-Level
Support Driver .................................................................................... 7-11
Pathnames and Targets of Links............................................................. 7-12
Table 7-3.
Table A-1.
Error Messages........................................................................................ A-1
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About This Manual
The LabWindows/CVI Programmer Reference Manual contains
information to help you develop programs in LabWindows/CVI. The
LabWindows/CVI Programmer Reference Manual is intended for use by
LabWindows users who have already completed the Getting Started with
LabWindows/CVI tutorial. To use this manual effectively, you should be
familiar with Getting Started with LabWindows/CVI, the LabWindows/CVI
User Manual, DOS, Windows, and the C programming language.
Organization of This Manual
follows:
•
Chapter 1, LabWindows/CVI Compiler, describes LabWindows/CVI
compiler specifics, C language extensions, 32-bit compiler issues,
debugging levels, and user protection.
•
Chapter 2, Using Loadable Compiled Modules, describes the
advantages and disadvantages of using compiled code modules in your
application. It also describes the kinds of compiled modules available
in LabWindows/CVI and includes programming guidelines for
•
•
•
•
Chapter 3, Windows 95/NT Compiler/Linker Issues, describes the
different kinds of compiled modules available under
LabWindows/CVI for Windows 95/NT and includes programming
Chapter 4, Windows 3.1 Compiler/Linker Issues, describes the
different kinds of compiled modules available under
LabWindows/CVI for Windows 3.1 and includes programming
Chapter 5, UNIX Compiler/Linker Issues, describes the kinds of
compiled modules available under LabWindows/CVI for UNIX and
includes programming guidelines for modules you generate with
external compilers.
Chapter 6, Building Multiplatform Applications, contains guidelines
and caveats for writing platform-independent LabWindows/CVI
applications. LabWindows/CVI currently runs under Windows 3.1
and Windows 95/NT for the PC, and Solaris 1 and Solaris 2 for the
SPARCstation.
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About This Manual
•
Chapter 7, Creating and Distributing Standalone Executables and
externally compiled modules, and other files interact with your
executable file. This chapter also describes how to perform error
checking in a standalone executable program. You can create
LabWindows/CVI environment.
•
•
•
•
Chapter 8, Distributing Libraries and Function Panels, describes how
specify library dependencies.
Chapter 9, Checking for Errors in LabWindows/CVI, describes
errors in LabWindows/CVI libraries and compiled external modules.
Appendix A, Errors and Warnings, contains an alphabetized list of
compiler warnings, compiler errors, link errors, DLL loading errors,
Appendix B, Customer Communication, contains forms to help you
problems and a form you can use to comment on the product
documentation.
•
•
The Glossary contains an alphabetical list of terms used in this manual
and a description of each.
The Index contains an alphabetical list of key terms and topics used in
this manual, including the page where each one can be found.
Conventions Used in This Manual
The following conventions are used in this manual.
<>
-
Angle brackets enclose the name of a key on the keyboard—for example,
<Shift>.
A hyphen between two or more key names enclosed in angle brackets
denotes that you should simultaneously press the named keys—for
example, <Ctrl-Alt-Delete>.
»
The » symbol leads you through nested menu items and dialog box options
to a final action. The sequence File»Page Setup»Options» Substitute
Fonts directs you to pull down the File menu, select the Page Setup item,
select Options, and finally select the Substitute Fonts options from the
last dialog box.
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This icon to the left of bold italicized text denotes a note, which alerts you
to important information.
This icon to the left of bold italicized text denotes a caution, which advises
you of precautions to take to avoid injury, data loss, or a system crash.
!
bold
Bold text denotes the names of menus, menu items, parameters, or dialog
box buttons.
bold italic
Bold italic text denotes an activity objective, note, caution, or warning.
italic
Italic text denotes variables, emphasis, a cross reference, or an introduction
to a key concept. This font also denotes text from which you supply the
appropriate word or value.
monospace
Text in this font denotes text or characters that you should literally enter
from the keyboard, sections of code, programming examples, and syntax
examples. This font is also used for the proper names of disk drives, paths,
directories, programs, functions, filenames and extensions, and for
statements and comments taken from programs.
monospace bold
monospace italic
paths
Bold text in this font denotes the messages and responses that the computer
automatically prints to the screen.
Italic text in this font denotes that you must enter the appropriate words or
values in the place of these items.
Paths in this manual are denoted using backslashes (\) to separate drive
names, directories, folders, and files.
Related Documentation
You may find the following documentation helpful while programming in
LabWindows/CVI:
•
•
•
Microsoft Developer Network CD, Microsoft Corporation,
Redmond WA
Programmer’s Guide to Microsoft Windows 95, Microsoft Press,
Redmond WA, 1995
Harbison, Samuel P. and Guy L. Steele, Jr., C: A Reference Manual,
Englewood Cliffs, NJ: Prentice-Hall, Inc., 1995
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Customer Communication
National Instruments wants to receive your comments on our products and
manuals. We are interested in the applications you develop with our
products, and we want to help you if you have problems with them. To
make it easy for you to contact us, this manual contains comment and
technical support forms for you to complete. These forms are in
Appendix B, Customer Communication, at the end of this manual.
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1
LabWindows/CVI Compiler
This chapter describes LabWindows/CVI compiler specifics, C language extensions, 32-bit
compiler issues, debugging levels, and user protection.
Overview
The LabWindows/CVI compiler is a 32-bit ANSI C compiler. The kernel of the
LabWindows/CVI compiler is the lcc ANSI C compiler (© Copyright 1990, 1991, 1992, 1993
David R. Hanson). It is not an optimizing compiler, but instead focuses on debugging, user
protection, and platform independence. Because the compiler is an integral part of the
LabWindows/CVI environment and features a limited set of straightforward options, it is also
easy to use.
LabWindows/CVI Compiler Specifics
This section describes specific LabWindows/CVI compiler limits, options, defines, and
diversions from the ANSI C standard.
Compiler Limits
Table 1-1 shows the compiler limits for LabWindows/CVI.
Table 1-1. LabWindows/CVI Compiler Limits
Coding Attribute
Maximum nesting of #include
Limit
32
Maximum nesting of #if, #ifdef
Maximum number of macro parameters
Maximum number of function parameters
Maximum nesting of compound blocks
Maximum size of array/struct types
16
32
64
32
231
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Chapter 1
LabWindows/CVI Compiler
Compiler Options
You can set the LabWindows/CVI compiler options by selecting Options»Compiler Options
in the Project window. This command opens a dialog box that allows you to set
LabWindows/CVI compiler options. For a discussion of these options, refer to the Compiler
Options section in Chapter 3, Project Window, of the LabWindows/CVI User Manual.
Compiler Defines
The LabWindows/CVI compiler accepts compiler defines through the Compiler Defines
command in the Options menu of the Project window. For more information, refer to the
Compiler Defines section in Chapter 3, Project Window, of the LabWindows/CVI User
Manual.
C Language Non-Conformance
LabWindows/CVI for UNIX does not allow you to pass a structas one of a series of
unspecified variable arguments. Because of this, va_arg(ap,type) is not legal in
LabWindows/CVI if typeis a struct type.
LabWindows/CVI accepts the #line preprocessor directive, but ignores it.
C Language Extensions
The LabWindows/CVI compiler has several extensions to the C language. The purpose is to
make the LabWindows/CVI compiler compatible with the commonly used C extensions in
external compilers under Windows 95/NT.
Keywords That Are Not ANSI C Standard
LabWindows/CVI for Windows 3.1 accepts the non-ANSI C keywords pascal, PASCAL, and
_pascal, but ignores them.
Calling Conventions (Windows 95/NT Only)
You can use the following calling convention qualifiers in function declarations:
cdecl
_cdecl
__cdecl(recommended)
_stdcall
__stdcall(recommended)
In Microsoft Visual C/C++, Borland C/C++, and Symantec C/C++, the calling convention
normally defaults to __cdeclif you do not use a calling convention qualifier. You can,
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Chapter 1
LabWindows/CVI Compiler
however, set options to cause the calling convention to default to __stdcall. The behavior
window. When you create a new project, the default calling convention is __cdecl.
In Watcom C/C++, the default calling convention is not __cdeclor __stdcall. You must
use the -4s(80486 Stack-Based Calling) option when you compile a module in Watcom for
use in LabWindows/CVI. Refer to the Compatibility with External Compilers section in
Chapter 3, Windows 95/NT Compiler/Linker Issues. The -4soption causes the stack-based
calling convention to be the default. In LabWindows/CVI under Watcom compatibility mode,
the default calling convention is always the stack-based convention. It cannot be changed. The
LabWindows/CVI compiler accepts the __cdecland __stdcallconventions under
Watcom, except that floating point and structure return values do not work in the __cdecl
calling convention. National Instruments recommends that you avoid using __cdeclwith
Watcom.
In the __cdeclcalling convention and the Watcom stack-based calling convention, the
calling function is responsible for cleaning up the stack. Functions can have a variable number
of arguments.
In the __stdcallcalling convention, the called function is responsible for cleaning up the
stack. Functions with a variable number of arguments do not work in __stdcall. If you use
the __stdcallqualifier on a function with a variable number of arguments,
LabWindows/CVI does not honor the qualifier. All compilers pass parameters and return
values in the same way for __stdcallfunctions, except for floating point and structure
return values.
National Instruments recommends the __stdcallcalling convention for all functions
exported from a DLL, except functions with a variable number of arguments. Visual Basic
and other non-C Windows programs expect DLL functions to be __stdcall.
Import and Export Qualifiers
You can use the following qualifiers in variable and function declarations:
__declspec(dllimport)
__declspec(dllexport)
__import
__export
_import
_export
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LabWindows/CVI Compiler
At this time, not all these qualifiers work in all external compilers. The LabWindows/CVI
cvidef.hinclude file defines the following macros, which are designed to work in each
external compiler.
DLLIMPORT
DLLEXPORT
An import qualifier informs the compiler that the symbol is defined in a DLL. Declarations
of variables imported from a DLL require import qualifiers, but function declarations do not.
An export qualifier is relevant only in a project for which the target type is Dynamic Link
Library. The qualifier can be on the declaration or definition of the symbol, or both. The
qualifier instructs the linker to include the symbol in the DLL import library.
C++ Comment Markers
You can use double slashes (//) to begin a comment. The comment continues until the end of
the line.
Duplicate Typedefs
The LabWindows/CVI compiler does not report an error on multiple definitions of the same
typedef identifier, as long as the definitions are identical.
Structure Packing Pragma (Windows 3.1 and Windows 95/NT Only)
The packpragmacan be used within LabWindows/CVI to specify the maximum alignment
factor for elements within a structure. For example, assume the following structure definition:
struct t {
double d1;
char charVal;
short shortVal;
double d2;
};
If the maximum alignment is 1, the compiler can start the structure on any 1-byte boundary
and inserts no gaps between the structure elements.
If the maximum alignment is 8, the compiler must start the structure on an 8-byte boundary,
place shortValon a 2-byte boundary, and place d2on an 8-byte boundary.
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You can set the maximum alignment as follows:
#pragma pack(4) /* sets maximum alignment to 4 bytes */
#pragma pack(8) /* sets maximum alignment to 8 bytes */
#pragma pack() /* resets to the default*/
The maximum alignment the compiler applies to a structure is based on the last pack
pragmastatement it sees before the definition of the structure.
Program Entry Points (Windows 95/NT Only)
Under Windows 95/NT, you can use WinMaininstead of mainas the entry-point function to
your program. You might want to do this if you plan to link your executable using an external
compiler. You must include windows.hfor the data types that normally appear in the
WinMainparameter list. The following is the prototype for WinMainwith the Windows data
types reduced to intrinsic C types.
int __stdcallWinMain(void *hInstance, void *hPrevInstance,
char *lpszCmdLine int nCmdShow)
C Library Issues
This section discusses special considerations in LabWindows/CVI in the areas of low-level
I/O functions and the UNIX C library.
Using the Low-Level I/O Functions
Many functions in the UNIX libraries and the C compiler libraries for the PC are not ANSI C
Library. Under UNIX, you can call UNIX libraries for the non-ANSI C functions in
conjunction with LabWindows/CVI.
The low-level I/O functions open, close, read, write, lseek, and eofare not in the
ANSI C Standard Library. Under UNIX, these functions are available in the UNIX C library.
Refer to Chapter 5, UNIX Compiler/Linker Issues, for more information.
Under Windows, you can use these functions along with sopenand fdopenif you include
lowlvlio.h.
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Chapter 1
LabWindows/CVI Compiler
C Data Types and 32-Bit Compiler Issues
This section introduces the LabWindows/CVI compiler data types and discusses converting
16-bit source code to 32-bit source code.
Data Types
Table 1-2 shows the LabWindows/CVI allowable data types.
Table 1-2. LabWindows/CVI Allowable Data Types
Type
Size
Minimum
Maximum
127
char
8
–128
unsigned char
short
8
0
255
16
–32,768
32,767
65,535
231 –1
unsigned short
int; long int
unsigned int
unsigned long
float
16
0
32
–231
32
0
232 –1
32
0
232 –1
32
64
–3.40282E+38
–1.79769E+308
N/A
3.40282E+38
1.79769E+308
N/A
double; long double
pointers (void *)
enum
32
8, 16, or 32
–231
231 –1
The size of an enumeration type depends on the value of its enumeration constant.
In LabWindows/CVI, characters are signed, unless you explicitly declare them unsigned.
The types floatand doubleconform to 4-byte and 8-byte IEEE standard formats.
Converting 16-Bit Source Code to 32-Bit Source Code
If you convert a LabWindows for DOS application to a LabWindows/CVI application, use
this section as a guide after you complete the steps in Chapter 12, Converting LabWindows
for DOS Applications, of the Getting Started with LabWindows/CVI manual.
In general, if you make few assumptions about the sizes of data types, little difference exists
between a 16-bit compiler and a 32-bit compiler except for the larger capacity of integers and
the larger address space for arrays and pointers.
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For example, the code
int x;
declares a 2-byte integer in a 16-bit compiler such as LabWindows for DOS. In contrast,
a 32-bit compiler such as LabWindows/CVI handles this code as a declaration of a 4-byte
integer. In most cases, this does not cause a problem and the conversion is transparent,
because functions that use 2-byte integers in LabWindows for DOS use 4-byte integers in
LabWindows/CVI. However, this conversion does cause a problem when a program performs
one of the following actions:
•
Passes an array of 16-bit integers to a GPIB, VXI, or Data Acquisition (DAQ) function
If you use a 32-bit intarray to receive a set of 16-bit integers from a device,
LabWindows/CVI packs two 16-bit values into each element of the 32-bit array. Any
attempt to access the array on an element-by-element basis does not work. Declare the
array as shortinstead, and make sure any type specifiers that refer to it have the [b2]
modifier when you pass them as an argument to a Formatting and I/O Library function.
•
Uses an intvariable in a way that requires it to be a 2-byte integer
For example, if you pass an intargument by address to a function in the Formatting and
I/O Library, such as a Scansource or a Scan/Fmttarget, and it matches a %d[b2]or
%i[b2]specifier, it does not work correctly. Remove the [b2]modifier, or declare the
variable as short.
Conversely, if you pass a shortargument by address and it matches a %dor %ispecifier
without the [b2]modifier, it does not work correctly. Add the [b2]modifier.
Note
The default for %dis 2 bytes on a 16-bit compiler and 4 bytes on a 32-bit compiler.
In the same way, the default for intis 2 bytes on a 16-bit compiler, and 4 bytes on
a 32-bit compiler. This is why you do not have to make any modifications if the
All pointers are 32-bit offsets. LabWindows/CVI does not use the farpointers that have both
a segment selector and an offset, except in 16-bit Windows DLLs under Windows 3.1.
LabWindows/CVI for Windows 3.1 calls 16-bit DLLs through a special interface
LabWindows/CVI generates from the header file for the DLL. For more information, refer to
the Using 32-Bit Watcom Compiled Modules under Windows 3.1 and 16-Bit Windows DLLs
sections in Chapter 4, Windows 3.1 Compiler/Linker Issues.
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Debugging Levels
You can compile the source modules in your application to include debugging information. If
you do so, you can use breakpoints and view or modify variables and expressions while your
program is suspended. You set the debugging level by selecting Options»Run Options in the
Project window. Refer to the Run Options section in Chapter 3, Project Window, of the
LabWindows/CVI User Manual for information on debugging levels.
User Protection
User protection detects invalid program behavior that LabWindows/CVI cannot otherwise
detect during compilation. LabWindows/CVI reports such invalid program behavior as user
protection errors. When you set the debugging level to Standard or Extended,
LabWindows/CVI maintains extra information for arrays, structures, and pointers, and uses
the information at run time to determine the validity of addresses.
Two groups of user protection errors exist based upon two characteristics: severity level and
error category. In each case, the ANSI C standard states that programs with these errors have
undefined behavior. The two severity levels are as follows:
•
Non-Fatal errors include expressions that are likely to cause problems, but do not
directly affect program execution. Examples include bad pointer arithmetic, attempts to
free pointers more than once, and comparisons of pointers to different array objects. The
expression is invalid and its behavior is undefined, but execution can continue.
•
Fatal errors include expressions that LabWindows/CVI cannot execute without causing
major problems, such as causing a general protection fault. For example, dereferencing
an invalid pointer value is a fatal error.
Error categories include pointer protection, dynamic memory protection, library protection,
and general protection errors. Each of these categories includes subgroups as described in the
following sections.
Array Indexing and Pointer Protection Errors
The pointer protection errors catch invalid operations with pointers and arrays. In this section,
these errors are grouped by the type of expression that causes the error or the type of invalid
pointer involved.
Pointer Arithmetic (Non-Fatal)
Pointer arithmetic expressions involve a pointer sub-expression and an integer
sub-expression. LabWindows/CVI generates an error when the pointer sub-expression is
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invalid or when the arithmetic operation results in an invalid pointer expression. The
following user protection errors involve pointer arithmetic:
•
•
•
Pointer arithmetic involving uninitialized pointer
Pointer arithmetic involving null pointer
Out-of-bounds pointer arithmetic (calculation of an array address that results in a pointer
value either before the start, or past the end of the array)
•
•
•
•
•
•
Pointer arithmetic involving pointer to freed memory
Pointer arithmetic involving invalid pointer
Pointer arithmetic involving address of non-array object
Pointer arithmetic involving pointer to function
Array index too large
Negative array index
Pointer Assignment (Non-Fatal)
LabWindows/CVI generates pointer assignment errors when you assign invalid values to
pointer variables. These warnings can help determine when a particular pointer becomes
invalid. The following user protection errors involve pointer assignment:
•
•
Assignment of uninitialized pointer value
Assignment of out-of-bounds pointer expression (assignment of an address before the
start, or past the last element, of an array)
•
•
Assignment of pointer to freed memory
Assignment of invalid pointer expression
Pointer Dereference Errors (Fatal)
Dereferencing of invalid pointer values is a fatal error because it can cause a memory fault or
other serious problem. The following user protection errors involve pointer dereferencing:
•
•
•
Dereference of uninitialized pointer
Dereference of null pointer
Dereference of out-of-bounds pointer (dereference using a pointer value before the start,
or past the end, of an array)
•
•
•
•
Dereference of pointer to freed memory
Dereference of invalid pointer expression
Dereference of data pointer for use as a function
Dereference of function pointer for use as data
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•
•
Dereference of a pointer to an n-byte type where less than n bytes exist in the object
Dereference of unaligned pointer (UNIX only)
Pointer Comparison (Non-Fatal)
LabWindows/CVI generates pointer comparison errors for erroneous pointer comparison
expressions. The following user protection errors involve pointer comparison:
•
•
•
•
•
•
Comparison involving uninitialized pointer
Comparison involving null pointer
Comparison involving invalid pointer
Comparison of pointers to different objects
Pointer comparison involving address of non-array object
Comparison of pointers to freed memory
Pointer Subtraction (Non-Fatal)
LabWindows/CVI generates pointer subtraction errors for erroneous pointer subtraction
expressions. The following user protection errors involve pointer subtraction:
•
•
•
•
•
•
Subtraction involving uninitialized pointer
Subtraction involving null pointer
Subtraction involving invalid pointer
Subtraction of pointers to different objects
Pointer subtraction involving address of non-array object
Subtraction of pointers to freed memory
Pointer Casting (Non-Fatal)
LabWindows/CVI generates a pointer casting error when you cast a pointer expression to type
(AnyType *) and not enough space exists for an object of type AnyTypeat the location the
pointer expression specifies. This occurs only when casting a dynamically allocated object for
the first time, such as with the code (double *) malloc(1). In this example,
LabWindows/CVI reports the following error: Not enough space for casting
expression to 'pointer to double'.
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Dynamic Memory Protection Errors
Dynamic memory protection errors report illegal operations with dynamic memory and
corrupted dynamic memory during allocation and deallocation.
Memory Deallocation (Non-Fatal)
LabWindows/CVI generates memory deallocation errors when the pointer is not the result of
a memory allocation. The following user protection errors involve memory deallocation:
•
•
•
•
Attempt to free uninitialized pointer
Attempt to free pointer to freed memory
Attempt to free invalid pointer expression
Attempt to free pointer not allocated with mallocor calloc
Memory Corruption (Fatal)
LabWindows/CVI generates memory corruption errors when a memory
allocation/deallocation detects corrupted memory. During each dynamic memory operation,
LabWindows/CVI verifies the integrity of the memory blocks it uses in the operation. When
you set the Debugging Level to Extended, LabWindows/CVI thoroughly checks all dynamic
memory on each memory operation. LabWindows/CVI generates the following error when it
discovers a problem: Dynamic memory is corrupt.
General Protection Errors
LabWindows/CVI also checks for stack overflow and missing return values:
•
•
Stack overflow (fatal)
Missing return value (non-fatal)
The missing return value error means that a non-void function (one you do not declare with
voidreturn type) returned, but did not returned a value.
Library Protection Errors
Library functions sometimes generate errors when they receive invalid arguments.
LabWindows/CVI error checking is sensitive to the requirements of each library function.
The following errors involve library protection:
•
•
•
•
•
Null pointer argument to library function
Uninitialized pointer argument to library function
Passing a pointer to freed memory to a library function
Array argument too small
Passing by reference a scalar argument to a library function that expects an array
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•
•
Missing terminating null in string argument
Passing a string to a library function that expects a character reference parameter
LabWindows/CVI library functions return error codes in a variety of cases. If you enable the
Break on Library Errors option in the Run Options command in the Options menu of the
Project window, LabWindows/CVI suspends execution after a library function returns one of
these errors. A message appears that displays the name of the function and either the return
value or a string that explains why the function failed.
Disabling User Protection
Occasionally, you might want to disable user protection to avoid run-time errors that do not
cause problems in your program.
Disabling Protection Errors at Run-Time
You can use the SetBreakOnProtectionErrorsfunction in the Utility Library to
programmatically control whether LabWindows/CVI suspends execution when it encounters
a protection error. This function does not affect the Break on Library Errors feature.
Disabling Library Errors at Run-Time
The Break on Library Errors option in the Run Options command in the Options menu of
the Project window lets you choose whether LabWindows/CVI suspends execution when a
library function returns an error code. The option takes effect when you start executing the
project. You can override the initial setting in your program by using the
SetBreakOnLibraryErrorsfunction in the Utility Library. Use of this function does not
affect the reporting of other types of library protection errors.
Disabling Protection for Individual Pointer
You can disable pointer checking for a particular pointer by casting it first to an arithmetic
type and then back to its original type, as shown in the following macro:
#define DISABLE_RUNTIME_CHECKING(ptr)((ptr) = (void *)
((unsigned)(ptr)))
{
char *charPointer;
/* run-time checking is performed for charPointer before this
line */
DISABLE_RUNTIME_CHECKING(charPointer);
/* no run-time checking is performed for charPointer after this
line */
}
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This macro could be useful in the following situation: LabWindows/CVI reports erroneous
run-time errors because you set a pointer to dynamic memory in a source module and you then
resize it in an object module. The following steps describe how this error occurs:
1. You declare a pointer in a source module you compile with debugging enabled. You then
assign to the pointer an address that mallocor callocreturns:
AnyType *ptr;
ptr = malloc(N);
2. You reallocate the pointer in an object module so that it points to the same location in
memory as before. This might occur if you call the reallocfunction or free the pointer
and then reassign it to memory that you allocate with malloc:
ptr = realloc(ptr, M); /* M > N */
or
free(ptr);
ptr = malloc(M);
3. You use the same pointer in a source module you compile with debugging enabled. At
this point, LabWindows/CVI still expects the pointer to point to a block of memory of
the original size (N).
*(ptr+(M-1)) /* This generates a fatal run-time error, */
/* even though it is a legal expression. */
To prevent this error, use the DISABLE_RUNTIME_CHECKINGmacro to disable checking for
the pointer after you allocate memory for it in the source module:
ptr = malloc(N);
DISABLE_RUNTIME_CHECKING(ptr);
Disabling Library Protection Errors for Functions
You can disable or enable library protection errors by placing pragmas in the source code.
LabWindows/CVI ignores these pragmas when you compile without debugging information,
that is, if the debugging level is None. For example, the following two pragmas enable and
disable library checking for all the function declarations that occur after the pragma within a
header or source file. The pragmas affect only the functions declared in the file in which the
pragmas occur. These pragmas do not affect nested include files.
#pragma EnableLibraryRuntimeChecking
#pragma DisableLibraryRuntimeChecking
The following pragmas enable and disable library checking for a particular function. You
must declare the function before the occurrence of the pragma.
#pragma EnableFunctionRuntimeChecking function
#pragma DisableFunctionRuntimeChecking function
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These two pragmas enable and disable run-time checking for a particular library function
throughout the module in which they appear. You can use them to override the effects of the
EnableLibraryRuntimeCheckingand DisableLibraryRuntimeCheckingpragmas
for individual functions. If both of these pragmas occur in a module for the same function,
LabWindows/CVI uses only the last occurrence.
Note
These pragmas affect all protection, including run-time checking of function
arguments, for all calls to a specific library function. To disable breaking on
errors for a particular call to a library function, use the Utility Library function
SetBreakOnLibraryErrors. To disable the run-time checking of argument
expressions for a particular call to a library function, use the Utility Library
function SetBreakOnProtectionErrors.
Note
You cannot use pragmas to disable protection for the functions in the
statically linked libraries including User Interface, RS-232, TCP, DDE,
Formatting and I/O, Utility, X Property, and ANSI C libraries unless you place the
DisableLibraryRuntimeCheckingpragma at the top of the library header file.
Details of User Protection
Pointer Casting
A cast expression consists of a left parenthesis, a type name, a right parenthesis, and an
operand expression. The cast causes the compiler to convert the operand value to the type that
appears within the parenthesis.
C programmers occasionally have to cast a pointer to one data type to a pointer to another data
type. Because LabWindows/CVI does not restructure the user protection information for each
cast expression, certain types of cast expressions implicitly disable run-time checking for the
pointer value. In particular, casting a pointer expression to the following types disables
run-time checking on the resulting value:
•
•
•
•
Pointer to a pointer: (AnyType **)PointerExpression
Pointer to a structure:(struct AnyStruct *)PointerExpression
Pointer to an array:(AnyType (*)[])PointerExpression
Any non-pointer type:(unsigned)PointerExpression,
(int)PointerExpression, and so on
Note
An exception exists. Casts that you apply implicitly or explicitly to the void *
values you obtain from mallocor callocdo not disable user protection.
Casting a pointer to one arithmetic type to a pointer to a different one, such as (int *),
(unsigned *), (short *), and so on, does not affect run-time checking on the resulting
pointer, nor does casting a pointer to a void pointer (void *).
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Dynamic Memory
LabWindows/CVI provides run-time error checking for pointers and arrays in dynamically
allocated memory.
You can use the ANSI C library functions mallocor callocto allocate dynamic memory.
These functions return void *values that you must cast to some other type before the
memory can be used. During program execution, LabWindows/CVI uses the first such cast
on the return value of each call to these functions to determine the type of the object that will
be stored in the dynamic memory. Subsequent casts to different types can disable checking on
the dynamic data, as explained in the Pointer Casting discussion in this section.
You can use the reallocfunction to resize dynamically allocated memory. This function
increases or decreases the size of the object associated with the dynamic memory.
LabWindows/CVI adjusts the user protection information accordingly.
Avoid Unassigned Dynamic Allocation in Function Parameters
The LabWindows/CVI run-time error checking mechanism dynamically allocates data to
keep track of pointers that you dynamically allocate in your program. When you no longer
use the pointers, LabWindows/CVI uses garbage collection to deallocate its corresponding
dynamic memory.
A case exists where the garbage collection fails to retrieve all the memory it allocated. This
occurs when you pass the return value of one function to another function, the return value is
a pointer to dynamically allocated memory, and you do not assign the pointer to a variable in
the argument expression. The following is an example:
MyFunc (1, 2, malloc(7));
This call passes the return value from mallocto MyFuncbut does not assign it to a variable.
If you make this call repeatedly in your program with run-time checking enabled, you lose a
small amount of memory each time.
Change the code as follows to avoid this problem.
void *p;
MyFunc (1, 2, p = malloc(7));
The following code also works and uses better programming style.
void *p;
p = malloc(7);
MyFunc (1, 2, p);
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Library Functions
The LabWindows/CVI library functions that take pointer arguments or that return pointers
incorporate run-time checking for those arguments and return values. However, you must be
careful when passing arguments to library functions that have void *parameters, such as
GetCtrlAttributeand GetCtrlValin the User Interface Library and memcpyand
memsetin the ANSI C library. If you use a void *cast when you pass an argument to a
function that expects a variably typed argument, you disable run-time checking for that
argument. Some examples follow:
{
int value;
GetCtrlVal(panel, ctrl, &value);
/* CORRECT
*/
GetCtrlVal(panel, ctrl, (void *)&value);/* INCORRECT */
}
{
char *names[N], *namesCopy[N];
memcpy(namesCopy, names, sizeof (names));/* CORRECT */
memcpy((void *)namesCopy, (void *)names, sizeof names);
/* INCORRECT */
}
Unions
LabWindows/CVI performs only minimal checks for uniontype variables. If a union
contains pointers, arrays, or structs, LabWindows/CVI does not maintain user protection
information for those objects.
Stack Size
Your program uses the stack for passing function parameters and storing automatic local
variables. You can set the maximum stack size by selecting the Options»Run Options in the
Project window. Table 1-3 shows the stack size ranges LabWindows/CVI supports.
Table 1-3. Stack Size Ranges for LabWindows/CVI
Platform
Windows 3.1
Minimum
4 KB
Default
40 KB
Maximum
40 KB
1 MB
Windows 95/NT
Solaris 1 for Sun
Solaris 2 for Sun
100 KB
100 KB
100 KB
250 KB
250 KB
250 KB
5 MB
5 MB
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Note
For LabWindows/CVI for Windows 3.1, the actual stack size approaches 64 KB
when you set the Debugging level to None.
Include Paths
The Include Paths command in the Options menu of the Project window specifies the
directory search path for include files. The Include Paths dialog box has two lists, one for
include paths specific to the project, and one for paths not specific to the project.
When you install VXIplug&play instrument drivers, the installation program places the
include files for the drivers in a specific VXIplug&play include directory. LabWindows/CVI
also searches that directory for include files.
Include Path Search Precedence
LabWindows/CVI searches for include files in the following locations and in the
following order:
1. Project list
2. Project-specific include paths
3. Non-project-specific include paths
4. The paths listed in the Instrument Directories dialog box
5. The subdirectories under the cvi\toolslibdirectory
6. The cvi\instrdirectory
7. The cvi\includedirectory
8. The cvi\include\ansidirectory
9. The VXIplug&play include directory
10. The cvi\sdk\includedirectory (Windows 95/NT only)
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2
Using Loadable
Compiled Modules
your application. It also describes the kinds of compiled modules available in
LabWindows/CVI and includes programming guidelines for modules you generate with
external compilers.
Refer to Chapter 3, Windows 95/NT Compiler/Linker Issues, Chapter 4, Windows 3.1
Compiler/Linker Issues, or Chapter 5, UNIX Compiler/Linker Issues, in this manual for more
information on platform-specific programming guidelines for modules that external
compilers generate.
About Loadable Compiled Modules
Several methods exist for using compiled modules in LabWindows/CVI. You can load
compiled modules directly into the LabWindows/CVI environment as instrument driver
programs or as user libraries, so they are accessible to any project. You can list compiled
modules in your project, so they are accessible only within that project. You can use compiled
modules dynamically in your program with LoadExternalModule, RunExternalModule,
and UnloadExternalModule. Any compiled module you use in LabWindows/CVI must be
in one of the following forms:
•
•
•
A .objfile on the PC, or a .ofile under UNIX, that contains one object module
A .libfile on the PC, or a .afile under UNIX, that contains one or more object modules
A .dllfile that contains a Windows DLL (Windows only)
You can create any of these compiled modules in LabWindows/CVI under Windows 95/NT,
or using a compatible external compiler. Under Windows 3.1, LabWindows/CVI can create
only .objfiles. Under UNIX, LabWindows/CVI can create only .ofiles.
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Advantages and Disadvantages of Using Loadable Compiled Modules
in LabWindows/CVI
Using compiled modules in LabWindows/CVI has the following advantages:
•
•
•
Compiled modules run faster than source modules. Compiled modules do not contain the
debugging and user protection code LabWindows/CVI generates when it compiles
source modules. Compiled modules you generate in external compilers can run faster
because of optimization.
LabWindows/CVI recompiles the source modules in a project each time you open the
project. Also, if an instrument driver program file is a source module, LabWindows/CVI
recompiles it each time you load the instrument driver. LabWindows/CVI does not
recompile compiled modules when you open a project or load an instrument driver.
In standalone executables, you can dynamically load compiled modules but not source
modules.
•
•
You can install compiled modules, but not source modules, into the Library menu.
You can provide libraries for other developers without giving them access to your source
code.
Using compiled modules in LabWindows/CVI has the following disadvantages:
•
You cannot debug compiled modules. Because compiled modules do not contain any
•
Compiled modules do not include run-time error checking or user protection.
Using a Loadable Compiled Module as an Instrument Driver
Program File
An instrument driver is a set of high-level functions with graphical function panels to make
programming easier. It encapsulates many low-level operations, such as data formatting and
GPIB, RS-232, and VXI communication, into intuitive, high-level functions. An instrument
driver usually controls a physical instrument, but it also can be a software utility. The Using
Instrument Drivers and Instrument Menu sections of Chapter 3, Project Window, of the
LabWindows/CVI User Manual describe how to use instrument drivers.
To develop and debug an instrument driver, load its program file into LabWindows/CVI as a
source file. After you finish debugging it, you can compile the program file into an object file
or a Windows 95/NT DLL. The next time you load the instrument driver, LabWindows/CVI
loads the compiled module, which loads and runs faster that the source module.
Refer to the LabWindows/CVI Instrument Driver Developers Guide for information on how
to create an instrument driver.
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If the instrument driver program file is a compiled module, it must adhere to the requirements
outlined for each operating system in Chapter 3, Windows 95/NT Compiler/Linker Issues,
Chapter 4, Windows 3.1 Compiler/Linker Issues, and Chapter 5, UNIX Compiler/Linker
Issues, of this manual.
Using a Loadable Compiled Module as a User Library
You can install your own libraries into the Library menu. A user library has the same form
as an instrument driver. You can load as a user library anything that you can load into the
Instrument menu, provided the program is in compiled form. Refer to the Using Instrument
Drivers and the Instrument Menu sections of Chapter 3, Project Window, of the
LabWindows/CVI User Manual for more information. The main difference between modules
you load as instrument drivers and those you load as user libraries is that you can unload
instrument drivers using the Unload command in the Instrument menu, but you cannot
unload user libraries. You cannot edit and recompile user libraries while they are loaded.
Install user libraries by selecting the Library Options command in the Project Options
menu. The next time you run LabWindows/CVI, the libraries load automatically and appear
at the bottom of the Library menu.
You can develop a user library module to provide support functions for instrument drivers or
any other modules in your project. By installing a module through the Library Options
a .fpfile without any classes or functions. In that case, LabWindows/CVI loads the library
at startup but does not include the library name in the Library menu.
User libraries must adhere to the requirements outlined for the target operating system.
Chapter 3, Windows 95/NT Compiler/Linker Issues, Chapter 4, Windows 3.1
Compiler/Linker Issues, and Chapter 5, UNIX Compiler/Linker Issues, of this manual, discuss
operating system requirements.
Using a Loadable Compiled Module in the Project List
You can include compiled modules directly in the project list.
Note
To use a DLL in your project under Windows 95/NT, you must include the DLL
import library (.lib) file in the project list rather than the DLL.
Even when you include a source module in the project list, you can instruct LabWindows/CVI
to create an object module on disk when it compiles the file instead of debuggable code in
memory. To do this, double click in the O column next to the source file in the Project window.
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Compiled modules must adhere to the requirements outlined for the target operating
system. Chapter 3, Windows 95/NT Compiler/Linker Issues, Chapter 4, Windows 3.1
Compiler/Linker Issues, and Chapter 5, UNIX Compiler/Linker Issues, of this manual, discuss
operating system requirements.
Using a Loadable Compiled Module as an External Module
You can load a compiled module dynamically from your program. A module you load
dynamically is called an external module. You can load, execute, and unload this external
module programmatically using LoadExternalModule, GetExternalModuleAddr, and
While you develop and debug the external module, you can list it in the project as a source
file. After you finish debugging the module, you can compile it into an object file or a
Windows 95/NT DLL. External modules must adhere to the requirements outlined for the
target operating system. Chapter 3, Windows 95/NT Compiler/Linker Issues, Chapter 4,
Windows 3.1 Compiler/Linker Issues, and Chapter 5, UNIX Compiler/Linker Issues, of this
manual, discuss operating system requirements.
Notification of Changes in Run State
You might have to notify certain compiled modules whenever your program starts, suspends,
continues, or stops. For example, if a compiled module has asynchronous callbacks, you must
prevent the callbacks from executing when program execution suspends at a breakpoint.
LabWindows/CVI has a callback mechanism you can use to inform a compiled module of
changes in the program status.
To notify a compiled module of changes in the run state, add a function with the name
__RunStateChangeCallbackto the compiled module. LabWindows/CVI automatically
installs the callback for you.
The run state change callback must be in a compiled file, not in a source file. More than one
compiled module can contain functions with this name, because LabWindows/CVI never
enters it into the global name space. The prototype for the callback is as follows:
void CVICALLBACK __RunStateChangeCallback(int action)
libsupp.hdefines the actions in the following enumerated type:
enum {
kRunState_Start,
kRunState_Suspend,
kRunState_Resume,
kRunState_AbortingExecution,
kRunState_Stop,
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kRunState_EnableCallbacks,
kRunState_DisableCallbacks
};
The following examples show typical program state changes.
Example 1
kRunState_Start
kRunState_EnableCallbacks
/* user program execution begins */
.
.
.
/* a breakpoint or run-time error occurs, or user presses the
Terminate Execution key combination */
kRunState_DisableCallbacks
kRunState_Suspend
/* program execution suspends; CVI environment resumes */
.
.
.
/* user requests the execution be resumed, through the "Continue",
"Step Over", etc., commands */
kRunState_Resume
kRunState_EnableCallbacks
/* user program execution resumes */
.
.
.
/* user program execution completes normally */
kRunState_DisableCallbacks
kRunState_Stop
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Using Loadable Compiled Modules
Example 2
kRunState_Start
kRunState_EnableCallbacks
/* user program execution begins */
.
.
.
/* a breakpoint or run-time error occurs, or user presses the
Terminate Execution key combination */
kRunState_DisableCallbacks
kRunState_Suspend
/* program execution suspends; CVI environment resumes */
.
.
.
/* user selects the Terminate Execution command */
kRunState_DisableCallbacks /* even though callbacks already
disabled */
kRunState_AbortingExecution
/* long jump out of user program */
kRunState_DisableCallbacks /* even though callbacks already
disabled */
kRunState_Stop
Note
A Resumenotification does not always follow a Suspendnotification. A Stop
notification can follow a Suspendnotification without an intervening Resume
notification.
Note
Run state change callbacks do not work if you link your program in an external
compiler. Also, external compilers report link errors if you have multiple run state
change callbacks.
Using Run State Change Callbacks in a DLL
You can include one or more run state change callbacks in a DLL. To do so, you must build
the DLL in the LabWindows/CVI development environment, and each run state change
callback must be in a separate object or static library file in the DLL project. If you include a
run state change callback in a DLL, or in an object or static library file that another user might
include in a DLL, take special care in two areas:
•
Use caution when you call into other DLLs in response to a kRunState_Stopmessage.
When you use your DLL in a standalone executable, the DLL receives the
kRunState_Stopmessage when the executable terminates. The order in which
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Using Loadable Compiled Modules
Windows 95/NT unloads DLLs at process termination is not well-defined. Therefore, the
DLL you call into might no longer be loaded. This can cause a general protection fault.
Nevertheless, when you use your DLL in a program in the LabWindows/CVI
development environment, it is often necessary to call into DLLs to release resources
after each run. To solve this dilemma, use conditional code to release resources only if
you are running in the LabWindows/CVI development environment. An example
follows.
#include <utility.h>
switch (runState)
{
case kRunState_Stop:
if (! InStandaloneExecutable())
{ /* call into other DLLs to release resources */ }
/* release resources, including unloading DLLs */
break;
}
It is always safe to call into the LabWindows/CVI Run-time Engine in a run state change
callback.
•
If your DLL uses global variables that can become stale after each program execution in
the LabWindows/CVI development environment, re-initialize the variables in response
to the kRunState_Startor kRunState_Stopmessage. For example, memory that
you allocate using LabWindows/CVI ANSI C functions such as mallocor callocis no
longer valid when you restart your program. If your DLL has global variables that point
to allocated memory, set those pointers to NULLin response to the kRunState_Start
or kRunState_Stopmessage.
Compiled Modules that Contain Asynchronous Callbacks
A compiled module can call a source code function asynchronously. This can happen through
interrupts or signals. In Windows 95/NT, the compiled module can call the source code
function from a thread other than the main thread. The call takes place asynchronously with
respect to the normal execution of the source code in your program.
The execution and debugging system in the LabWindows/CVI development environment is
not prepared to handle this asynchronous execution. Consequently, the compiled module must
announce to LabWindows/CVI that it is calling asynchronously into source code. It does this
by calling EnterAsyncCallbackbefore calling the function, and calling
ExitAsyncCallbackafter calling the function. EnterAsyncCallbackand
ExitAsyncCallbackhave one parameter, which is a pointer to a buffer of size
ASYNC_CALLBACK_ENV_SIZE. You must pass the same buffer into ExitAsyncCallback
that you passed into EnterAsyncCallbackbecause the buffer stores state information. The
definition of ASYNC_CALLBACK_ENV_SIZE and the prototypes for these two functions are
in libsupp.h.
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Windows 95/NT
Compiler/Linker Issues
This chapter describes the different kinds of compiled modules available under
LabWindows/CVI for Windows 95/NT and includes programming guidelines
for modules you generate with external compilers.
Under Windows 95/NT, the LabWindows/CVI compiler is compatible with four external
32-bit compilers: Microsoft Visual C/C++, Borland C/C++, Watcom C/C++, and
Symantec C/C++. This manual refers to the four compilers as the compatible external
compilers.
In LabWindows/CVI under Windows 95/NT, you can do the following:
•
•
•
•
Load 32-bit DLLs, through the standard import library mechanism
Create 32-bit DLLs and DLL import libraries
Create library files and object files
Call the LabWindows/CVI libraries from executables or DLLs created with any of the
four compatible external compilers
•
•
•
Create object files, library files, and DLL import libraries that the compatible external
compilers can use
Load object files, library files, and DLL import libraries created with any of the four
compatible external compilers
Call Windows Software Development Kit (SDK) functions
This chapter discusses these capabilities.
Loading 32-Bit DLLs under Windows 95/NT
Under Windows 95/NT, LabWindows/CVI can load 32-bit DLLs. LabWindows/CVI links to
DLLs through the standard 32-bit DLL import libraries that you generate when you create
32-bit DLLs with any of the compilers. Because LabWindows/CVI links to DLLs in this way,
you cannot specify a DLL file directly in your project. You must specify the DLL import
library file instead.
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DLLs for Instrument Drivers and User Libraries
Under Windows 95/NT, LabWindows/CVI does not directly associate DLLs with instrument
drivers or user libraries. However, LabWindows/CVI can associate instrument drivers and
user libraries with DLL import libraries. Each DLL must have a DLL import library (.lib)
file. In general, if the program for an instrument driver or user library is in the form of a DLL,
you must place the DLL import library in the same directory as the function panel (.fp) file.
The DLL import library specifies the name of the DLL that LabWindows/CVI searches for
using the standard Windows DLL search algorithm.
LabWindows/CVI makes an exception to facilitate using VXIplug&play instrument driver
DLLs. When you install a VXIplug&play instrument driver, the installation program
does not place the DLL import library in the same directory as the .fpfile. If a .fpfile
is in the VXIplug&play directory, LabWindows/CVI searches for an import library in
the VXIplug&play library directory before it looks for a program file in the directory of
the .fpfile, unless you list the program file in the project.
Using The LoadExternalModule Function
When you use the LoadExternalModulefunction to load a DLL at run time, you must
specify the pathname of the DLL import library, not the name of the DLL.
Link Errors when Using DLL Import Libraries
A DLL import library must not contain any references to symbols that the DLL does not
export. If it does, LabWindows/CVI reports a link error. If you load the DLL using
LoadExternalModule, the GetExternalModuleAddrfunction reports an undefined
references (–5) error. You can solve this problem by using LabWindows/CVI to generate an
import library. Refer to the Generating an Import Library discussion later in this section.
DLL Path (.pth) Files Not Supported
The DLL import library contains the filename of the DLL. LabWindows/CVI uses the
standard Windows DLL search algorithm to find the DLL. Thus, DLL path (.pth)
files do not work under Windows 95/NT.
16-Bit DLLs Not Supported
LabWindows/CVI for Windows 95/NT does not load 16-bit DLLs. If you want to do this, you
must obtain a 32-to-16-bit thunking DLL and a 32-bit DLL import library.
Run State Change Callbacks in DLLs
You can include run state change callbacks in DLLs you build in LabWindows/CVI. When
running a program in LabWindows/CVI, a run state change callback receives notification
when the program starts, suspends, resumes, and stops. If you include a run state change
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callback in a DLL, you must take special care. Refer to the Notification of Changes in Run
State section in Chapter 2, Using Loadable Compiled Modules, of this manual, for a detailed
discussion of run state change callbacks.
DllMain
Each DLL can have a DllMainfunction, except that the Borland compiler uses
DllEntryPointas the name. The operating system calls the DllMainfunction with various
messages. To generate the template for a DllMainfunction, use the Insert Constructs
command in the Edit menu of a Source window.
Use caution when inserting code in the PROCESS_ATTACHand PROCESS_DETACHcases. In
particular, avoid calling into other DLLs in these two cases. The order in which
Windows 95/NT initializes DLLs at startup and unloads them at process termination is not
well-defined. Thus, the DLLs you want to call might not be in memory when your DllMain
receives the PROCESS_ATTACHor PROCESS_DETACHmessage.
It is always safe to call into the LabWindows/CVI Run-time Engine in a run state change
callback, as long as you do so before calling CloseCVIRTE.
Releasing Resources when a DLL Unloads
When a program terminates, the operating system disposes resources your DLL allocates. If
your DLL remains loaded throughout program execution, it does not need to dispose
resources explicitly when the system unloads it at program termination. However, if the
program unloads your DLL during program execution, it is a good idea for your DLL to
dispose of any resources it allocates. It can release resources in the DllMainfunction in
response to the PROCESS_DETACHmessage. The DLL can also release resources in a function
that it registers with the ANSI C atexitfunction. The system calls the function you register
when the DLL receives the PROCESS_DETACHmessage.
If your DLL calls into the LabWindows/CVI Run-time Engine DLL, it can allocate resources
such as user interface panels. If a program unloads your DLL during execution, you might
want to dispose these resources by calling functions such as DisposePanelin the
LabWindows/CVI Run-time Engine. On the other hand, as explained in the previous section,
it is generally unsafe to call into other DLLs in response to the PROCESS_DETACHmessage.
To solve this dilemma, you can use the CVIRTEHasBeenDetachedfunction in the
Utility Library. It is always safe to call the CVIRTEHasBeenDetachedfunction.
CVIRTEHasBeenDetachedreturns FALSE until the main Run-time Engine DLL,
cvirte.dll, receives the PROCESS_DETACHmessage. Consequently, if
CVIRTEHasBeenDetachedreturns FALSE, your DLL can safely call functions in
LabWindows/CVI Run-time Engine to release resources.
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Note
cvirte.dllcontains the User Interface, Utility, Formatting and I/O, RS-232,
ANSI C, TCP, and DDE Libraries.
Generating an Import Library
If you do not have a DLL import library or if the one you have contains references the DLL
does not export, you can generate an import library in LabWindows/CVI. You must have an
include file that contains the declarations of all the functions and global variables you want to
access from the DLL. The calling conventions of the function declarations in the include file
must match the calling convention of the functions in the DLL. For example, if the DLL
exports functions using the __stdcallcalling convention, the function declarations in the
include file must contain the __stdcallkeyword. Load the include file into a Source
window, and select the Generate DLL Import Library command in the Options menu.
Default Unloading/Reloading Policy
Some fundamental differences exist in the way Windows 95/NT and Windows 3.1 handle a
DLL that multiple processes use.
Windows 95/NT creates a separate data space for each process that uses the DLL.
Windows 3.1 creates only one data space for all processes that use the DLL.
Windows 95/NT notifies a DLL each time a process loads or unloads it. Windows 3.1 does
not notify a DLL each time a process loads or unloads it. Windows 3.1 notifies the DLL only
when the first process loads it and the last process unloads it.
LabWindows/CVI for Windows 95/NT unloads DLLs, by default, after each execution of a
user program in the development environment. This behavior more accurately simulates
what happens when you execute a standalone executable, and it is more suitable for
Windows 95/NT DLLs that rely on load/unload notification on each execution of a program.
You can change the default behavior by turning off the Unload DLLs After Each Run option
in the Run Options dialog box of the Project window. National Instruments recommends,
however, that you leave the default behavior in effect.
Compatibility with External Compilers
LabWindows/CVI for Windows 95/NT can be compatible at the object code level with
any of the four compatible external compilers (Microsoft Visual C/C++, Borland C/C++,
Watcom C/C++, and Symantec C/C++). Because these compilers are not compatible with
each other at the object code level, LabWindows/CVI can be compatible with only one
external compiler at a time. This manual refers to the compiler with which your copy of
LabWindows/CVI is currently compatible as the current compatible compiler.
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Choosing Your Compatible Compiler
When installing LabWindows/CVI, you must choose your compatible compiler. If you want
to change your choice of compatible compiler later, you can run the installation program and
change to another compatible compiler.
You can see which compatible compiler is active in LabWindows/CVI by selecting the
Compiler Options command in the Options menu of the Project window.
Object Files, Library Files, and DLL Import Libraries
If you create an object file, library file, or DLL import library in LabWindows/CVI, you can
use the file only in the current compatible compiler or in a copy of LabWindows/CVI
that you installed with the same compatibility choice. For detailed information on using
LabWindows/CVI-generated object and static library files in external compilers, refer to
the Using LabWindows/CVI Libraries in External Compilers section later in this chapter.
If you load an object file, library file, or DLL import library file in LabWindows/CVI,
you must have created the file in the current compatible compiler or in a copy of
LabWindows/CVI that you installed with the same compatibility choice. If you have
a DLL but you do not have a compatible DLL import library, LabWindows/CVI reports an
error when you attempt to link your project.
To create a compatible import library, you must have an include file that contains the
declarations of all the functions and global variables you want to access from the DLL.
Load the include file into a Source window, and select the Generate DLL Import Library
command in the Options menu.
Make sure the calling conventions of the function declarations in the include file match the
calling convention of the functions in the DLL. Whereas DLLs usually export functions with
the __stdcallcalling convention, the __stdcallkeyword is sometimes missing from the
function declarations in the associated include files. If you generate an import library from an
include file that does not agree with the calling convention the DLL uses, you can successfully
build a project that contains the import library, but LabWindows/CVI usually reports a general
protection fault when you run the project.
Compatibility Issues in DLLs
In general, you can use a DLL without regard to the compiler you used to create it. Only the
DLL import library must be created for the current compatible compiler. Some cases exist,
however, in which you cannot call a DLL that you created using one compiler from an
executable or DLL that you created using another compiler. If you want to create DLLs that
you can use in different compilers, design the Application Programming Interface (API) for
your DLL to avoid such problems. The following are areas in which the DLLs that external
compilers create are not fully compatible.
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Structure Packing
The compilers differ in their default maximum alignment of elements within structures.
If your DLL API uses structures, you can guarantee compatibility among the different
compilers by using the packpragma to specify a specific maximum alignment factor. Place
this pragma in the DLL include file, before the definitions of the structures. You can choose
any alignment factor. After the structure definitions, reset the maximum alignment factor back
to the default, as in the following example:
#pragma pack (4) /* set maximum alignment to 4 */
typedef struct {
char a;
int b;
} MyStruct1;
typdef struct {
char a;
double b;
} MyStruct2;
#pragma pack () /* reset max alignment to default */
LabWindows/CVI predefines the __DEFALIGNmacro to the default structure alignment of
the current compatible compiler.
Bit Fields
Borland C/C++ uses the smallest number of bytes necessary to hold the bit fields you specify
in a structure. The other compilers always use 4-byte elements. You can force compatibility
by adding a dummy bit field of the correct size to pad the set of contiguous bit fields so that
they fit exactly into a 4-byte element. Example:
typedef struct {
int a:1;
int b:1;
int c:1;
int dummy:29;
} MyStruct;
/* pad to 32 bits */
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Returning Floats and Doubles
The compilers return floatand doublescalar values using different mechanisms. This is
true of all calling conventions, including __stdcall. The only solution for this problem is
to change your DLL API so that it uses output parameters instead of return values for double
and floatscalars.
Returning Structures
For functions you do not declare with the __stdcallcalling convention, the compilers
return structures using different mechanisms. For functions you declare with__stdcall, the
compilers return structures in the same way, except for 8-byte structures. National
Instruments recommends that your DLL API use structure output parameters instead of
structure return values.
Enum Sizes
By default, Watcom uses the smallest integer size necessary to represent the largest enum
value: 1 byte, 2 bytes, or 4 bytes. The other compilers always use 4 bytes. Force compatibility
by using the -ei(Force Enums to Type Int) option with the Watcom compiler.
Long Doubles
In Borland C/C++, long doublevalues are 10 bytes. In the other compilers, they are 8 bytes.
In LabWindows/CVI, they are always 8 bytes. Avoid using long doublein your DLL API.
Differences between LabWindows/CVI and the External Compilers
LabWindows/CVI does not work with all the non-ANSI extensions each external compiler
provides. Also, in cases where ANSI does not specify the exact implementation,
LabWindows/CVI does not always agree with the external compilers. Most of these
differences are obscure and rarely encountered. The following are the most important
differences you might encounter:
• wchart_tis only one-byte in LabWindows/CVI.
•
64-bit integers do not exist in LabWindows/CVI.
• long doublevalues are 10 bytes in Borland C/C++ but 8 bytes in LabWindows/CVI.
•
•
You cannot use structured exception handling in LabWindows/CVI.
You cannot use the Watcom C/C++ __cdeclcalling convention in LabWindows/CVI for
functions that return floator doublescalar values or structures. In Watcom, __cdecl
is not the default calling convention.
•
LabWindows/CVI does not define _MSC_VER, __BORLANDC__, __WATCOMC__, and
__SC__. The external compilers each define one of these macros. If you port code
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originally developed under one of these external compilers to LabWindows/CVI, you
might have to manually define one of these macros.
External Compiler Versions Supported
The following versions of each external compiler work with LabWindows/CVI for
Windows 95/NT:
•
•
•
•
Microsoft Visual C/C++, version 2.2 or higher
Borland C/C++, version 4.51 or higher
Watcom C/C++, version 10.5 or higher
Symantec C/C++, version 7.2 or higher
Required Preprocessor Definitions
When you use an external compiler to compile source code that includes any of the
LabWindows/CVI include files, add the following to your preprocessor definitions:
_NI_mswin32_
Multithreading and the LabWindows/CVI Libraries
Although the LabWindows/CVI environment is not multithreaded, you can use
LabWindows/CVI Libraries in the following multithreaded contexts:
•
When you call the LabWindows/CVI Libraries from a multithreaded executable you
create in LabWindows/CVI or in an external compiler.
•
When you call the LabWindows/CVI Libraries from a DLL that a multithreaded
executable loads. You can create the DLL in LabWindows/CVI or in an external
compiler.
•
When you call the LabWindows/CVI Libraries from an object or static library file that
you dynamically load in a multithreaded executable. You can create the object or library
file in LabWindows/CVI or in an external compiler.
All the LabWindows/CVI libraries are multithreaded safe when used outside of the
LabWindows/CVI development environment.
For detailed information on how to use the LabWindows/CVI User Interface Library in a
multithreaded program, refer to Chapter 3, Programming with the User Interface Library, in
the LabWindows/CVI User Interface Reference Manual.
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Using LabWindows/CVI Libraries in External Compilers
Under Windows 95/NT, you can use the LabWindows/CVI libraries in any of the four
compatible external compilers. You can create executables and DLLs that call the
LabWindows/CVI libraries. LabWindows/CVI ships with the run-time DLLs that contain all
the libraries. Executable files you create in LabWindows/CVI also use these DLLs. The
cvi\extlibdirectory contains DLL import libraries and a startup library, all compatible
with your external compiler. Never use the .libfiles in the cvi\bindirectory in an external
compiler.
You must always include the following two libraries in your external compiler project:
cvisupp.lib /* startup library */
cvirt.lib
/* import library to DLL containing:*/
/*
/*
/*
/*
/*
/*
User Interface Library
Formatting and I/O Library
RS-232 Library
DDE Library
TCP Library
*/
*/
*/
*/
*/
*/
Utility Library
You can add the following static library file from cvi\extlibto your external compiler
project:
analysis.lib /* Analysis or Advanced Analysis Library */
You can add the following DLL import library files from cvi\extlibto your external
compiler project:
gpib.lib
/* GPIB/GPIB 488.2 Library
*/
dataacq.lib /* Data Acquisition Library */
easyio.lib /* Easy I/O for DAQ Library */
visa.lib
nivxi.lib
ivi.lib
/* VISA Transition Library
/* VXI Library
/* IVI Library
*/
*/
*/
cviauto.lib /* ActiveX Automation Library*/
If you use an instrument driver that makes references to both the GPIB and VXI libraries, you
can include both gpib.liband nivxi.libto resolve the references to symbols in those
libraries. If you do not have access to one of these files, you can replace it with one of
following files:
gpibstub.obj /* stub GPIB functions
vxistub.obj /* stub VXI functions
*/
*/
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If you use an external compiler that requires a WinMainentry point, the following optional
library allows you to define only mainin your program.
cviwmain.lib
/* contains a WinMain() function which */
/* calls main() */
Include Files for the ANSI C Library and the LabWindows/CVI Libraries
The cvirt.libimport library contains symbols for all the LabWindows/CVI libraries,
except the ANSI C standard library. When you create an executable or DLL in an external
compiler, you use the compiler’s own ANSI C standard library. Because of this, you must use
the external compiler’s include files for the ANSI C library when compiling source files.
Although the include files for the other LabWindows/CVI libraries are in the cvi\include
directory, the LabWindows/CVI ANSI C include files are in the cvi\include\ansi
directory. Thus, you can specify cvi\includeas an include path in your external compiler
while at the same time using the external compiler’s version of the ANSI C include files.
Note
Use the external compiler’s ANSI C include files only when you compile a source
file that you intend to link using the external compiler. If you intend to link the file
in LabWindows/CVI, use the LabWindows/CVI ANSI C include files. This is true
regardless of which compiler you use to compile the source file.
For more information, refer to the Setting Up Include Paths for LabWindows/CVI, ANSI C,
and SDK Libraries section later in this chapter.
Standard Input/Output Window
One effect of using the external compiler’s ANSI C standard library is that the printfand
scanffunctions do not use the LabWindows/CVI Standard Input/Output window. If you
want to use printfand scanf, you must create a console application, which is called a
character-mode executable in Watcom.
You can continue to use the LabWindows/CVI Standard Input/Output Window by calling the
FmtOutand ScanInfunctions in the Formatting and I/O library.
Resolving Callback References from .UIR Files
When you link your program in LabWindows/CVI, LabWindows/CVI keeps a table of the
non-static functions that are in your project. When your program calls LoadPanelor
LoadMenuBar, the LabWindows/CVI User Interface Library uses this table to find the
callback functions associated with the objects you load from the user interface resource
(.uir) file. This is true whether you run your program in the LabWindows/CVI development
environment or as a standalone executable.
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When you link your program in an external compiler, the external compiler does not make
such a table available to the User Interface Library. To resolve callback references, you must
use LabWindows/CVI to generate an object file that contains the necessary table.
1. Create a LabWindows/CVI project that contains the .uirfiles your program uses, if you
do not already have one.
2. Select the External Compiler Support command in the Build menu of the Project
window. A dialog box appears.
3. In the UIR Callbacks Object File control, enter the pathname of the object file you want
to generate. When you click on the Create button, LabWindows/CVI generates the
all the .uirfiles in the project. When you modify and save any of these .uirfiles,
LabWindows/CVI regenerates the object file to reflect the changes.
4. Include this object file in the external compiler project you use to create the executable.
5. You must call InitCVIRTEat the beginning of your mainor WinMainfunction. Refer
to the Calling InitCVIRTE and CloseCVIRTE section later in this chapter.
Linking to Callback Functions Not Exported from a DLL
Normally, the User Interface Library searches for callback functions only in the table of
functions in the executable. When you load a panel or menu bar from a DLL, you might want
to link to non-static callback functions the DLL contains, but does not export. You can do this
by calling LoadPanelExand LoadMenuBarEx. When you pass the DLL module handle to
LoadPanelExand LoadMenuBarEx, the User Interface Library searches the table of
callback functions the DLL contains before searching the table that the executable contains.
Refer to Chapter 4, User Interface Library Function Reference, of the LabWindows/CVI User
Interface Reference Manual for detailed information on LoadPanelExand
LoadMenuBarEx.
If you create your DLL in LabWindows/CVI, LabWindows/CVI includes the table of
functions in the DLL automatically. If you create your DLL using an external compiler, you
must generate an object file that contains the necessary table as follows.
1. Create a LabWindows/CVI project that contains the .uirfiles your DLL loads, if you
do not already have one.
2. Select the External Compiler Support command in the Build menu of the Project
window. A dialog box appears.
3. In the UIR Callbacks Object File control, enter the pathname of the object file you want
to generate. When you click on the Create button, LabWindows/CVI generates the
object file with a table that contains the names of all the callback functions referenced in
all the .uirfiles in the project. When you modify and save any of these .uirfiles,
LabWindows/CVI regenerates the object file to reflect the changes.
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4. Include this object file in the external compiler project you use to create the DLL.
5. You must call InitCVIRTEand CloseCVIRTEin your DLLMainfunction. Refer to the
Calling InitCVIRTE and CloseCVIRTE section later in this chapter.
Resolving References from Modules Loaded at Run-Time
Note
This section does not apply unless you use LoadExternalModuleto load object
or static library files.
Unlike DLLs, object and static library files can contain unresolved references. If you call
LoadExternalModuleto load an object or static library file at run time, the Utility
Library must resolve those references using function and variable symbols from the
LabWindows/CVI Run-time Engine, from the executable, or from previously loaded run-time
modules. A table of these symbols must be available in the executable. When you link your
program in LabWindows/CVI, LabWindows/CVI automatically includes a symbol table. This
is true whether you run your program in the LabWindows/CVI development environment or
as a standalone executable.
When you link your program in an external compiler, the external compiler does not make
such a table available to the Utility Library. LabWindows/CVI provides ways to help you
create the symbol table easily.
Resolving References to the LabWindows/CVI Run-Time Engine
LabWindows/CVI makes available two object files that contain symbol table information for
the LabWindows/CVI libraries that are in Run-time Engine DLLs:
•
Include cvi\extlib\refsym.objin your external compiler project if your run-time
modules refer to any symbols in the User Interface, Formatting and I/O, RS-232, DDE,
TCP, or Utility Library.
•
Include cvi\extlib\arefsym.objin your external compiler project if your run-time
modules refer to any symbols in the ANSI C library. If you have to use this object file and
you use Borland C/C++ to create your executable, you must choose Static Linking for the
Standard Libraries. In the Borland C/C++ IDE, you can do this in the New Target and
Target Expert dialog boxes.
Resolving References to Symbols Not in Run-Time Engine
If your run-time modules refer to any other symbols from your executable, you must use
LabWindows/CVI to generate an object file that contains a table of those symbols. Create an
include file that contains complete declarations of all the symbols your run-time modules
reference from the executable. The include file can contain nested #includestatements and
can contain executable symbols that your run-time modules do not refer to. If your run-time
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module references any of the commonly used Windows SDK functions, you can use the
cvi\sdk\include\basicsdk.hfile.
Execute the External Compiler Support command in the Build menu of the Project window.
A dialog box appears. Enable the Using Load External Module option. Enable the Other
Header File control. Enter the pathname of the object file to generate in the Object File
control. Click on the Create button to the right of the Object File control.
Include the object file in the external compiler project you use to create your executable. Also,
you must call InitCVIRTEat the beginning of your mainor WinMainfunction. Refer to the
Calling InitCVIRTE and CloseCVIRTE section later in this chapter.
Resolving Run-Time Module References to Symbols Not Exported
from a DLL
When you load an object or static library file from a DLL, you might want to resolve
references from that module using global symbols the DLL contains, but does not export. You
can do this by calling LoadExternalModuleEx. When you pass the DLL module handle to
LoadExternalModuleEx, the Utility Library searches the symbol table the DLL contains
before searching the table that the executable contains. Refer to Chapter 8, Utility Library, of
the LabWindows/CVI Standard Libraries Reference Manual for detailed information on
LoadExternalModuleEx.
If you create your DLL in LabWindows/CVI, LabWindows/CVI includes the table of symbols
compiler does not make such a table available to the Utility Library. Thus, when you use an
external compiler, you must include in your DLL one or more object files that contain the
necessary symbol tables. You can do this using the technique that the previous section,
Resolving References to Symbols Not in Run-Time Engine, describes. You must call
InitCVIRTEand CloseCVIRTEin your DLLMainfunction. Refer to the Calling InitCVIRTE
and CloseCVIRTE section later in this chapter.
When you use a compiled module in LabWindows/CVI, you can arrange for
LabWindows/CVI to notify the module of a change in the execution status such as start, stop,
suspend, or resume. You do this through a callback function that is always named
__RunStateChangeCallback.The Notification of Changes in Run State section, in
Chapter 2, Using Loadable Compiled Modules, of this manual, describes this in detail.
The run state change callback capability in LabWindows/CVI is necessary because the
LabWindows/CVI development environment executes your program as part of the
LabWindows/CVI process. When your program terminates, the operating system does not
release resources as it does when a process terminates. LabWindows/CVI attempts to release
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resources your program allocated, but your compiled module might have to do more. Also, if
the program suspends for debugging purposes, your compiled module might have to disable
interrupts.
When you run an executable created in an external compiler, it always executes as a separate
process, even when you debug it. Thus, the run state change callback facility is not necessary
and does not work. External compilers report link errors when you define
__RunStateChangeCallbackin more than one object file. If you include a run state
change callback in a compiled module that you intend to use both in LabWindows/CVI and
an external compiler, it is a good idea to put the callback function in a separate source file and
create a .libfile instead of a .objfile.
Calling InitCVIRTE and CloseCVIRTE
If you link an executable or DLL in an external compiler, you must call the InitCVIRTE
function at the beginning of your main, WinMain, or DLLMainfunction.
For an executable using mainas the entry point, your code must include the following
segment:
#include <cvirte.h>
int main (argc, char *argv[])
{
if (InitCVIRTE(0, argv, 0) == 0)
return (-1);/* out of memory */
/* your other code */
}
For an executable using WinMainas the entry point, your code must include the following
segment:
#include <cvirte.h>
int __stdcall WinMain (HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpszCmdLine, int nCmdShow)
{
if (InitCVIRTE(hInstance, 0, 0) == 0)
return (-1);/* out of memory */
/* your other code */
}
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For a DLL, you also have to call CloseCVIRTEin DLLMain. The code must include the
following segment:
#include <cvirte.h>
int __stdcall DllMain (HINSTANCE hinstDLL, DWORD fdwReason,
LPVOID pvReserved)
{
if (fdwReason == DLL_PROCESS_ATTACH)
{
if (InitCVIRTE (hinstDLL, 0, 0) == 0)
return 0; /* out of memory */
/* your other ATTACH code */
}
else if (fdwReason == DLL_PROCESS_DETACH)
{
/* your other DETACH code */
CloseCVIRTE ();
}
return 1;
}
Note
It is harmless, but unnecessary, to call these functions when you link your
executable in LabWindows/CVI for Windows 95/NT.
Watcom Stack Based Calling Convention
When you use the LabWindows/CVI libraries in the Watcom compiler, you must set the
default calling convention to the 80486 Stack Based calling convention. In the command line
compiler, this is the -4soption. In the Watcom IDE, you can set the default calling convention
by using the Options»C Compiler Switches command. The option is in the Target Processor
section of the Memory Model and Processor Switches section of the dialog box. If you do not
set this option, the Watcom linker reports undefined references to the LabWindows/CVI
run-time libraries.
Using Object and Library Files in External Compilers
When you use an external compiler to link a project that contains object or static library files
created in LabWindows/CVI, keep several points in mind.
Default Library Directives
Most compilers insert default library directives in the object and library files they generate.
A default library directive tells the linker to automatically include a named library in the link.
Normally, the directive refers to the name of C library files. If no files in the link contain a
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default library directive, and the linker does not explicitly include a C library in the link, the
linker reports unresolved function references in the object modules.
Object and static library files that LabWindows/CVI creates do not contain a default library
directive. This has different implications for each compiler.
Microsoft Visual C/C++
If you include in your project at least one object file that contains a default library directive,
the Visual C linker uses that library to resolve references in all object and library files, even
the files you create in LabWindows/CVI. Object files you create in Visual C usually contain
default library directives.
If you do not include in your project any object files or libraries you create in Visual C, you
can add the following Visual C libraries to the project to avoid link errors:
libc.lib
oldnames.lib
In the Visual C development environment, add these library names using the Input category
in the Link tab of the Project Settings dialog box.
Borland C/C++
No problems exist with the absence of default library directives when you use the Borland
compiler.
Watcom C/C++
Like Visual C, at least one object file must contain a default library directive to cause the
C library to be linked in. In addition, Watcom also requires a default library directive for
floating-point support.
If you do not include in your project any object files with the required directives, add the
following libraries, in the order shown, to the Libraries setting in the Windows Linking
Switches dialog box:
clib3s
math387
noemu387
Symantec C/C++
Each object file must have the default library directive for the C library. You must explicitly
add the Symantec C library to your project. The library filename is snn.liband it is in the
libsubdirectory under the Symantec installation directory.
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Borland Static versus Dynamic C Libraries
When you link a Borland C/C++ project that contains object or static library files you create
in LabWindows/CVI, it is a good idea to configure the Borland project to use the static version
of the Borland C libraries.
If you choose to use the dynamic C libraries, you must compile the LabWindows/CVI object
modules with the _RTLDLLmacro. You must define the _RTLDLLmacro in your source code
before including any of the Borland C header files.
Borland Incremental Linker
You cannot use your LabWindows/CVI object or static library files in the Borland C compiler
if you choose to use the incremental linker. Turn off the Use Incremental Linker option.
Borland C++ Builder
You cannot use your LabWindows/CVI object or static library files in the
Borland C++ Builder.
Watcom Pull-in References
The Watcom linker does not automatically link the startup code into your application or DLL.
Instead, it requires the module that contains main, WinMain, or DllMainto reference a
special symbol that the appropriate startup code module resolves. The Watcom compiler
automatically generates a reference to the special symbol into any module that containsmain,
WinMain, or DllMain. This symbol is __DLLstart_, _wstart2_, or _cstart_,
depending on whether the project is for a DLL, Windows application, or console application,
respectively. Object modules compiled in LabWindows/CVI do not contain such references.
LabWindows/CVI cannot generate the correct reference because it makes no distinction
between console and non-console applications.
You must include the symbol reference in your object file explicitly. For example, if your
module contains the mainfunction, you can generate the correct symbol reference by adding
the following to the source code for the module:
extern int _cstart_;
void *dummy = &_cstart_;
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Creating Object and Library Files in External Compilers
for Use in LabWindows/CVI
When you use a compatible external compiler to create an object or library file for
use in LabWindows/CVI, you must use the include files in the cvi\includeand
cvi\sdk\includedirectories. Ensure that these directories have priority over the
default paths for the compiler’s C library and SDK library include files.
You must choose the compiler options carefully. LabWindows/CVI tries to work with the
default options for each compiler as much as possible. In some cases, however, you have to
choose options that override the defaults. In other cases you must accept the defaults.
Microsoft Visual C/C++
LabWindows/CVI is compatible with all the defaults.
You must not use the following options to override the default settings:
/J
(Unsigned Characters)
(Struct Member Alignment)
(Stack Probes)
/Zp
/Ge
/Gh
/Gs
(Profiling)
(Stack Probes)
Borland C/C++
LabWindows/CVI is compatible with all the defaults.
You must not use the following options to override the default settings:
-a
(Data Alignment)
-K
(Unsigned Characters)
-u-
-N
(Turn Off Generation of Underscores)
(Test Stack Overflow)
-p
(Pascal Calling Convention)
(Register Calling Convention)
(Correct Pentium FDIV Flaw)
-pr
-fp
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Watcom C/C++
You must use the following options to override the default settings:
-ei
(Force Enums to Type Int)
-bt=nt
-mf
(Target Platform is Windows 95/NT)
(Flat Memory Model)
-4s
(80486 Stack-Based Calling)
(Disable Stack Depth Checking)
(Change Char Default to Signed)
(Generate In-Line 80x87 Code)
-s
-j
-fpi87
If your external object calls LoadExternalModuleor LoadExternalModuleEx, you must
also add the following compiler option:
-d__NO_MATH_OPS
You must not use the following option to override the default settings:
-Zp
(Structure Alignment)
Symantec C/C++
You must use the following options to override the default settings:
-mn
-f
(Windows 95/NT Memory Model)
(Generate In-Line 80x87 Code)
You must not use the following options to override the default settings:
-a
-P
-s
(Struct Alignment)
(Use Pascal Calling Convention)
(Check Stack Overflow)
Note
Certain specialized options can generate symbol references that cause link errors
in LabWindows/CVI. If you encounter a link error on a symbol in a module you
compiled in an external compiler and you do not recognize the symbol, try
changing your external compiler options.
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Creating Executables in LabWindows/CVI
You can create true 32-bit Windows executables in LabWindows/CVI for Windows 95/NT. In
LabWindows/CVI for Windows 3.1, you run standalone programs using a special executable
file that contains the LabWindows/CVI run-time libraries. If you run more than one program
at a time, Windows 3.1 loads extra copies of this special executable into memory. Under
Windows 95/NT, the LabWindows/CVI run-time libraries come in DLL form. Standalone
executables you create in LabWindows/CVI and executables you create in external compilers
use the same DLLs. If you run more than one program at a time, Windows 95/NT loads only
one copy of the DLL.
To create a standalone executable, you must first select Standalone Executable from the
submenu attached to the Target command in the Build menu of the Project window. When
you select Standalone Executable, the Create Standalone Executable command appears
below the Target command in the Build menu. The Create Standalone Executable
command under Windows 95/NT is the same as under Windows 3.1, except that you also can
specify version information to include in the executable in the form of a standard Windows
version resource.
Creating DLLs in LabWindows/CVI
In LabWindows/CVI for Windows 95/NT, you can create 32-bit DLLs. Along with each
DLL, LabWindows/CVI creates a DLL import library for your compatible compiler. You can
choose to create DLL import libraries compatible with all four external compilers.
You must have a separate project for each DLL you want to create. Select Dynamic Link
Library from the submenu attached to the Target command in the Build menu of the Project
window. When you select Dynamic Link Library, the Create Dynamic Link Library
command appears below the Target command in the Build menu. Refer to Chapter 3, Project
Window, in the LabWindows/CVI User Manual, for detailed information on the Create
Dynamic Link Library command.
You can debug the DLLs you create in LabWindows/CVI. Refer to the DLL Debugging
(Windows 95/NT Only) section in Chapter 3, Project Window, of the LabWindows/CVI
User Manual, for more information.
Customizing an Import Library
If you have to perform special processing in your DLL import library, you can customize it.
Instead of generating a .libfile, you can generate a .cfile that contains source code. If you
do this, however, you can export only functions from the DLL, not variables.
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To customize an import library, you must have an include file that contains the declarations
of all the functions you want to export from the DLL. Load the include file into a Source
window, and execute the Generate DLL Import Source command in the Options menu.
After you have generated the import source, you can modify it, including making calls to
functions in other source files. Create a new project that contains the import source file and
any other files it refers to. Select Static Library from the submenu attached to the Target
command in the Build menu of the Project window. Execute the Create Static Library
command.
Note
This import source code does not operate in the same way as a normal DLL import
library. When you link a normal DLL import library into an executable, the
operating system attempts to load the DLL as soon as the program starts. The
import source code LabWindows/CVI generates does not load the DLL until you
call one of the functions it exports.
Preparing Source Code for Use in a DLL
When you create a DLL, you must address the following issues that can affect your source
code and include file:
•
•
•
The calling convention you use to declare the functions you want to export
How you specify which DLL functions and variables you want to export
Marking imported symbols in the DLL include file you distribute
This section discusses how you can address these issues when you create your DLL in
LabWindows/CVI. If you create your DLL in an external compiler, the approach is very
similar. The external compilers, however, do not agree in all aspects. This chapter also
discusses these differences.
Some of the information in this section is very technical and complex. Recommendations on
the best approaches to these issues are at the end of the section. These recommendations are
intended to make creating the DLL as simple as possible, and to make it easy to use the same
source code in LabWindows/CVI and the external compilers.
Calling Convention for Exported Functions
If you intend for only C or C++ programs to use your DLL, you can use the __cdeclor
Watcom stack-based calling convention to declare the functions you want to export. If,
however, you want your DLL to be callable from environments such as Microsoft Visual
Basic, you must declare the functions you want to export with the __stdcallcalling
convention.
You must do this by explicitly defining the functions with the __stdcallkeyword. This is
true whether or not you choose to make __stdcallthe default calling convention for your
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project. You must use the __stdcallkeyword in the declarations in the include file you
distribute with the DLL.
Other platforms, such as UNIX or Windows 3.1 do not recognize the __stdcallkeyword.
If you work with source code that you might use on other platforms, you must use a macro in
place of __stdcall. The cvidef.hinclude file defines the DLLSTDCALLmacro for this
purpose.
The following are examples of using the DLLSTDCALLmacro.
int DLLSTDCALL MyIntFunc (void);
char * DLLSTDCALL MyStringFunc (void);
Note
You cannot use the __stdcallcalling convention on functions with a variable
number of arguments. Consequently, you cannot use such functions in Microsoft
Visual Basic.
Exporting DLL Functions and Variables
When a program uses a DLL, it can access only the functions or variables that the DLL
exports. The DLL can export only globally declared functions and variables. The DLL cannot
export functions and variables you declare as static.
If you create your DLL in LabWindows/CVI, you can indicate which functions and variables
to export in two ways: the include file method and the qualifier method.
Include File Method
You can use include files to identify symbols to export. The include files must contain the
declarations of the symbols you want to export. The include files can contain nested
#includestatements, but the DLL does not export the declarations in the nested include
files. In the Create Dynamic Link Library dialog box, you select from a list of all the include
files in the project.
The include file method does not work with other compilers. However, it is similar to the
.defmethod that the other compilers use.
Export Qualifier Method
You can mark each function and variable you want to export with an export qualifier.
Currently, not all compilers recognize the same export qualifier names. The most commonly
used qualifier is __declspec(dllexport). Some also recognize __export.
LabWindows/CVI recognizes both. The cvidef.hinclude file defines the DLLEXPORT
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macro to resolve differences among compilers and platforms. The following are examples of
using the DLLEXPORTmacro:
int DLLEXPORT DLLSTDCALL MyFunc (int parm) {}
int DLLEXPORT myVar = 0;
If the type of your variable or function requires an asterisk (*) in the syntax, put the qualifier
after the asterisk, as in the following example:
char * DLLEXPORT myVar = NULL;
Note
Borland C/C++ version 4.5x, requires that you place the qualifier before the
asterisk. In Borland C/C++ 5.0, you can place the qualifier on either side of the
asterisk.
When LabWindows/CVI creates a DLL, it exports all symbols for which export qualifiers
appear in either the definition or the declaration. If you use an export qualifier on the
definition and an import qualifier on the declaration, LabWindows/CVI exports the symbol.
The external compilers differ widely in their behavior on this point. Some require that the
declaration and definition agree.
Note
If you include in your DLL project an object or library file that defines exported
symbols, LabWindows/CVI cannot correctly create import libraries for each of the
external compilers. This problem does not arise if you use only source code files
in your DLL project.
Marking Imported Symbols in Include File Distributed with DLL
If your DLL might be used in a C or C++ environment, you must distribute an include file
with your DLL. The include file must declare all the symbols the DLL exports. If any of these
symbols are variables, you must mark them with an import qualifier. Variable declarations
require import qualifiers so that the compiler can generate the correct code for accessing the
variables.
You can use import qualifiers on function declarations, but they are not necessary. When you
use an import qualifier on a function declaration, external compilers can generate slightly
more efficient code for calling the function.
Using import qualifiers in the include file you distribute with your DLL can cause problems
if you use the same include file in the DLL source code:
•
•
If you mark variable declarations in the include file with import qualifiers and you use
the include file in a source file other than the one in which you define the variable,
LabWindows/CVI and the external compilers treat the variable as if it were imported
from another DLL and generate incorrect code as a result.
If you use export qualifiers in the definition of symbols and the include file contains
import qualifiers on the same symbols, some external compilers report an error.
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You can solve these problems in several different ways:
•
You can avoid exporting variables from DLLs, and thereby eliminate the need to use
import qualifiers. For each variable you want to export, you can create functions to
get and set its value or a function to return a pointer to the variable. You do not have
to use import qualifiers for functions. This is the simplest approach and works in
LabWindows/CVI. However, it does not work if you use an export qualifier in a
function definition and you create the DLL with an external compiler that requires
the declaration to use the same qualifier.
•
•
You can create a separate include file for distribution with the DLL.
You can use a special macro that resolves to either an import or export qualifier
depending on a conditional compilation flag. In LabWindows/CVI you can set the flag
in your DLL project by using the Compiler Defines command in the Options menu of
the Project window.
Recommendations
To make creating a DLL as simple as possible, adhere to the following recommendations:
•
•
•
Use the DLLSTDCALLmacro in the declaration and definition of all functions you want
to export. Do not export functions with a variable number of arguments.
Identify the symbols you want to export using the include file method. Do not use export
qualifiers. If you use an external compiler, use the .deffile method.
Do not export variables from the DLL. For each variable you want to export, create
functions to get and set its value or a function to return a pointer to the variable. Do not
use import qualifiers in the include file.
If you follow these recommendations, you reap the following benefits:
•
You can distribute with your DLL the same include file that you include in the source files
you use to make the DLL. This is especially useful when you create DLLs from
instrument drivers.
•
•
You can use the same source code to create the DLL in LabWindows/CVI and any of the
four compatible external compilers.
You can use your DLL in Microsoft Visual Basic or other non-C environments.
Automatic Inclusion of Type Library Resource for Visual Basic
The Create Dynamic Link Library command gives you the option to automatically create
a Type Library resource and include it in the DLL. When you use this option, Visual Basic
users can call the DLL without having to use a header file that contains Declarestatements
for the DLL functions. The command requires that you have a function panel file for
your DLL.
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If your function panel file contains help text, you can generate a Windows help file from it
using the Generate Windows Help command in the Options menu of the Function Tree
Editor window. The Create Dynamic Link Library command provides an option to include
links into the Window help file in the Type Library. These links allow Visual Basic users to
access the help information from the Type Library Browser.
Visual Basic has a more restricted set of types than C. Also, the Create Dynamic Link
Library command imposes certain requirements on the declaration of the DLL API. Use the
following guidelines to ensure that Visual Basic can use your DLL:
•
•
•
•
Always use typedefs for structure parameters and union parameters.
Do not use enum parameters.
Do not use structures that require forward references or that contain pointers.
Do not use pointer types except for reference parameters.
Creating Static Libraries in LabWindows/CVI
You can create static library (.lib) files in LabWindows/CVI for Windows 95/NT. Static
libraries are libraries in the traditional sense—a collection of object files—as opposed to a
dynamic link library or an import library. You can use just one project to create static library
files that work with all four compatible external compilers, but only if you include no object
or library files in the project.
You must have a separate project for each static library you want to create. Select Static
Library from the submenu attached to the Target command in the Build menu of the Project
window. When you select the Static Library option, the Create Static Library command
appears below the Target command in the Build menu. Refer to Chapter 4, Source,
Interactive Execution and Standard Input/Output Windows, of the LabWindows/CVI User
Manual for detailed information on the Create Static Library command.
Note
If you include a .libfile in a static library project, LabWindows/CVI includes all
object modules from the .libin the static library it creates. When you create an
executable or DLL, LabWindows/CVI uses only the necessary modules from the
.libfile.
Note
Do not set the default calling convention to __stdcallif you want to create a
static library for all four compatible external compilers.
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Creating Object Files in LabWindows/CVI
You can create an object file in LabWindows/CVI in one of two ways:
•
Include a source (.c) file in your project. Enable the Compile into Object option for the
source file by double-clicking in the space next to the filename in the Project window
under the column marked “O”. Compile the file.
•
Open a source (.c) file and select the Create Object File command in the Options menu
of the Source window.
In LabWindows/CVI for Windows 95/NT, you can choose to create an object file for only the
currently selected compiler or to create object files for all four compatible external compilers.
Note
Do not set the default calling convention to __stdcallif you want to create a
static object for all four compatible external compilers.
Calling Windows SDK Functions in LabWindows/CVI
You can call Windows SDK Functions in LabWindows/CVI for Windows 95/NT. If you
install the LabWindows/CVI full development system from CD-ROM, you can call all
the Windows SDK functions. Otherwise, you can call only a subset of the Windows SDK
functions.
To view help for the SDK functions, select the Windows SDK command in the Help menu
of any LabWindows/CVI window.
Windows SDK Include Files
You must include the SDK include files before the LabWindows/CVI include files. In this
way, you avoid problems that arise from function name and typedef conflicts between the
Windows SDK and the LabWindows/CVI libraries. The LabWindows/CVI include files
contain special macros and conditional compilation to adjust for declarations in the SDK
include files. Thus, LabWindows/CVI must process the SDK include files first, followed by
the LabWindows/CVI include files.
When you compile in LabWindows/CVI or when you use an external compiler to compile
your source files for linking in LabWindows/CVI, use the LabWindows/CVI SDK include
files. The LabWindows/CVI SDK include files are in the cvi\sdk\includedirectory. The
LabWindows/CVI compiler automatically searches the cvi\sdk\includedirectory. You
do not have to add it to your include paths.
When you use an external compiler to compile and link your source files, you must use the
SDK include files that come with the external compiler. If you use an external compiler to
compile your source files for linking in LabWindows/CVI, use the LabWindows/CVI SDK
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include files. For more information, refer to the Setting Up Include Paths for
LabWindows/CVI, ANSI C, and SDK Libraries section later in this chapter.
The number of SDK include files is very large. Normally, you have to include only
windows.hbecause it includes many, but not all, of the other include files. The inclusion of
windows.halong with its subsidiary include files significantly increases compilation time
and memory usage. WIN32_LEAN_AND_MEANis a macro from Microsoft that speeds
compiling by eliminating the less commonly used portions of windows.hand its subsidiary
include files. By default, LabWindows/CVI adds /DWIN32_LEAN_AND_MEANas a
compile-time definition when you create a new project. You can alter this setting by using the
Compiler Defines command in the Options menu of the Project window.
Using Windows SDK Functions for User Interface Capabilities
The LabWindows/CVI User Interface Library uses the Windows SDK. It is not designed to
be used in programs that attempt to build other user interface objects at the SDK level. While
no specific restrictions exist on using SDK functions in LabWindows/CVI, National
Instruments recommends that you base your user interface either entirely on the
LabWindows/CVI User Interface Library or entirely on another user interface development
system.
Using Windows SDK Functions to Create Multiple Threads
Although you can use the Windows SDK Functions to create multiple threads in a
multiple threads. For instance, if your main program terminates without destroying the
threads, they do not terminate. Also, the LabWindows/CVI libraries are not multithread safe
when you run a program in the LabWindows/CVI development environment.
For information on using the LabWindows/CVI libraries in a multithreaded executable, refer
to the Multithreading and the LabWindows/CVI Libraries section earlier in this chapter.
Automatic Loading of SDK Import Libraries
All the SDK functions are in DLLs. LabWindows/CVI and the four external compilers each
come with a number of DLL import libraries for the SDK functions. Most of the commonly
used SDK functions are in the following three import libraries:
kernel32.lib
gdi32.lib
user32.lib
LabWindows/CVI for Windows 95/NT automatically loads these three libraries when it starts
up and searches them to resolve references at link time. Thus, you do not have to include these
libraries in your project.
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If the LabWindows/CVI linker reports SDK functions as unresolved references, you must add
import libraries to your project. Refer to the cvi\sdk\sdkfuncs.txtfile for associations
of SDK import libraries to SDK functions. The import libraries are in the cvi\sdk\lib
directory.
Setting Up Include Paths for LabWindows/CVI, ANSI C,
The rules for using SDK include files are not the same as the rules for using ANSI C standard
library include files, which in turn are different than the rules for using the LabWindows/CVI
library include files. Refer to the Include Files for the ANSI C Library and the
LabWindows/CVI Libraries and Windows SDK Include Files sections earlier in this chapter.
You must set up your include paths differently depending on the environment in which you
compile and link. A discussion of each case follows.
Compiling in LabWindows/CVI for Linking in LabWindows/CVI
Use the LabWindows/CVI SDK and ANSI C include files. You do not have to set up any
special include paths; LabWindows/CVI finds the correct include files automatically.
Compiling in LabWindows/CVI for Linking in an External Compiler
Use the LabWindows/CVI SDK include files and the ANSI C include files from the external
compiler. Using the Include Paths command in the Options menu of the Project window, add
the following as explicit include paths at the beginning of the project-specific list:
cvi\include
cvi\sdk\include
directory containing the external compiler's ANSI C include paths
Compiling in an External Compiler for Linking in an External Compiler
Use the SDK and ANSI C include files from the external compiler. This happens
automatically. Specify the following directories as include paths in the external compiler for
the LabWindows/CVI library include files.
cvi\include
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Compiling in an External Compiler for Linking in LabWindows/CVI
Use the LabWindows/CVI SDK and ANSI C include files. Specify the following directories
as include paths in the external compiler.
cvi\include
cvi\include\ansi
cvi\sdk\include
Handling Hardware Interrupts under Windows 95/NT
Under Windows 3.1, you can handle hardware interrupts in a DLL. Under Windows 95, you
must handle hardware interrupts in a VxD. Under Windows NT, you must handle hardware
interrupts in a kernel-mode driver. You cannot create VxDs and kernel-mode drivers in
LabWindows/CVI. Instead, you must create them in Microsoft Visual C/C++, and you also
must have the Microsoft Device Driver Developer Kit (DDK).
Under Windows 3.1, it is extremely difficult to call source code into LabWindows/CVI at
interrupt time. Making such a call is easier under Windows 95/NT. Under Windows 95/NT,
you can arrange for the VxD or kernel-mode driver to call a function in your
LabWindows/CVI source code after the interrupt service routine exits. You do this by creating
a separate thread for your interrupt callback function. The callback function executes a loop
that blocks its thread until the interrupt service routine signals it. Each time the interrupt
service routine executes, it unblocks the callback thread. The callback thread then performs
its processing and blocks again.
LabWindows/CVI includes source code template files for a VxD and a kernel mode driver. It
also includes a sample main program to show you how to read and write registers on a board.
There is one set of files for Windows 95 and another for Windows NT.
The files are in cvi\vxd\win95and cvi\vxd\winnt. The file template.docin each
directory contains some basic information.
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4
Windows 3.1
Compiler/Linker Issues
This chapter describes the different kinds of compiled modules available under
LabWindows/CVI for Windows 3.1 and includes programming guidelines for
modules you generate with external compilers.
You can generate a compiled .objor .omodule from a source file within LabWindows/CVI
using the Create Object File command in the Options menu of a Source window. You can
then use the compiled module in any of the methods described in the About Loadable
Compiled Modules section in Chapter 2, Using Loadable Compiled Modules, of this manual.
Using 32-Bit Watcom Compiled Modules
under Windows 3.1
You must adhere to the following rules for a 32-bit Watcom compiled module (.objor
.libfile):
•
•
You can call LabWindows/CVI library functions.
If you make a call to the ANSI C Standard Library, you must include the
LabWindows/CVI header files instead of the Watcom header files.
•
•
•
You cannot call Watcom C library functions outside the scope of the ANSI C Standard
Library.
You can call open, close, read, write, lseek, or eof, but you must include
lowlvlio.hfrom LabWindows/CVI.
You cannot call functions in the Windows Software Development Kit (SDK), install
interrupts, perform DMA, or access hardware directly. These tasks must be done with a
Dynamic Link Library (DLL). The exception to this is that you can use the inpand outp
functions.
•
You cannot define a function as PASCAL, pascal, or _pascalif you intend to call it
from source code in LabWindows/CVI. Also, you cannot use any non-ANSI-C-standard
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keywords such as far, near, or hugein the declaration of functions to be called from
LabWindows/CVI source code.
•
•
If your Watcom-compiled module performs floating point operations, you must use
Watcom Version 9.5 or later.
Use the following options when you compile with Watcom IDE:
–
Set the Project Target Environment to 32-bit Windows 3.x, and set the Image Type
to Library [.lib].
–
–
–
–
–
–
–
–
Turn on the Disable Stack Depth Checking [-s] option.
Turn on the Change Char Default to Signed [-j] option.
Add -zw -d_NI_mswin16_to the Other Options.
Turn on the Generate as Needed [-of] option for Stack Frames.
Turn on the No Debugging Information option.
Turn on the In-line with Coprocessor [fpi87] option for Floating Point Model.
Turn on the Compiler default option for the Memory Model.
Turn on the 80486 Stack-Based Calling [-4s] option for the Target Processor.
•
Use the following compiler flags when using wcc386or wcc386p:
– -zw -s -4s -j -fpi87 -d0 -of -d_NI_mswin16_
–
You can use optimization flags in addition to the f, and you can use other flags, such
as -wn, which do not affect the generation of object code.
Using 32-Bit Borland or Symantec Compiled Modules
under Windows 3.1
In this section, CVI refers to both LabWindows/CVI and Watcom modules, while Borland
applies to both Borland and Symantec modules.
The following restrictions apply to Borland object modules:
•
Borland packs bit fields in structures differently than CVI, so you cannot share structures
with bit fields between Borland and CVI.
•
Borland returns structures, floats, and doubles differently than CVI. Therefore, functions
that return these types cannot be called from CVI if they are defined in Borland, or vice
versa. The exceptions are the ANSI C library functions that return doubles, which you
can call from within Borland compiled modules.
Note
This rule applies only to return values. You can use structs, floats and doubles as
output parameters without limitation.
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•
•
ANSI C library functions divand ldivreturn structures, and hence you cannot call
them from Borland compiled modules.
The type long doubleis the same as doublein CVI, while in Borland it is 10 bytes
long, so you cannot share objects of this type between Borland and CVI modules. This
affects the "%Le", "%Lf", "%Lg"format specifiers of printf, sprintf, fprintf,
scanf, sscanf, fscanf, and others.
•
Because you cannot share structures with bit fields between Borland and CVI, you cannot
use the macros in stdio.h(getc, putc, fgetc, fputc) in Borland objects.
• wchar_tis defined as a charin CVI, whereas it is defined as a shortin Borland,
so ANSI C library functions that return wchar_tor take wchar_tparameters do
not work.
Use the following options when you compile with Borland C 4.x:
•
•
•
•
•
•
Set the target to be a Win32 application.
Define _NI_mswin16_.
Set the include directories to point to cvi\includebefore other include directories.
Turn off the Allocate Enums as Ints option.
Turn off the Fast Floating Point option.
Use the C calling convention.
If you use a file with a .cextension, Borland C++ 4.x compiles it as a C source file. If your
file has a .cppextension, Borland C++ 4.x compiles it as a C++ source file; you must use
extern "C"for any functions or variables you want to access from a C file.
Use the following options when you compile with Symantec C++ 6.0:
•
•
•
•
•
Set the target to be a Win32s executable.
Define _NI_mswin16_.
Set the include directories to point to cvi\includebefore any other include directories.
Set Structure Alignment to 1 byte.
Turn off the Use Pascal Calling Convention option.
16-Bit Windows DLLs
You can call functions in a 16-bit DLL from source code or from a 32-bit compiled module.
You can compile your 16-bit DLL in any language using any compiler that generates DLLs.
If you want to program with DMA or interrupts, or access the Windows API, you must use a
Windows DLL.
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You must observe certain rules and restrictions in a DLL you want to use with
LabWindows/CVI. If you experience problems using a DLL in LabWindows/CVI,
you might have to contact the developer of the DLL to obtain modifications.
Because LabWindows/CVI is a 32-bit application, special glue code is required to
communicate with a 16-bit DLL. For some DLLs, LabWindows/CVI can automatically
generate this glue code from the include file when loading the DLL. For other DLLs, you
have to modify the glue source code and compile it with Watcom into a .objor .libfile.
The normal way of communicating with a DLL is by calling functions in the DLL. However,
cases exist where you must use other communication methods. The most typical case is that
of an interrupt service routine in a DLL that notifies the application when an interrupt occurs.
This is done through a callback function. Also, LabWindows/CVI can recognize messages
posted by a DLL through the Windows Application Programming Interface (API) function
PostMessageand initiate a callback function.
Helpful LabWindows/CVI Options for Working with DLLs
LabWindows/CVI provides two options that can be helpful when working with DLLs. The
options can be found in the Run Options menu of the Project window:
•
Enable the Check Disk Dates Before Each Run option when you iteratively modify a
DLL or DLL glue code file and run a LabWindows/CVI test program that calls into the
DLL. By enabling the Check Disk Dates Before Each Run option, you ensure that you
link the most recent version of the DLL and DLL glue code into your program. You can
leave this option enabled at all times. The only penalty is a small delay each time you
build or run the project.
•
By default, LabWindows/CVI does not unload and reload DLLs between each execution
of your program. This eliminates the delay in reloading the DLLs before each run. It
allows the DLLs to retain state information between each run. If, however, you use a DLL
that does not work correctly across multiple program executions, enable the Reload
DLLs Before Each Run option.
DLL Rules and Restrictions
To call into a 16-bit DLL from LabWindows/CVI 32-bit code, you must observe the following
rules and restrictions for DLL functions:
•
•
In the DLL header file, change all references to intinto references to short.
In the DLL header file, change all references to unsignedor unsigned intto
unsigned short.
•
•
You can declare the functions in the DLL as PASCALor as CDECL.
You cannot use variable argument functions.
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•
•
•
You can use the argument types char, unsigned char, int, unsigned int, short,
unsigned short, long, unsigned long, float, and double, as well as pointers to
any type, and arrays of any type. You can use typedefs for these types.
You can use the return types void, char, unsigned char, int, unsigned int,
short, unsigned short, long, and unsigned long, as well as pointers to any type.
You can use typedefs for these types.
You can use the return types float and double only if the DLL is created with a
Microsoft C compiler, and the functions returning floats or double are declared with the
cdeclcalling convention. You do not have to modify the glue code generated for
functions that return float or double values.
•
In the DLL header file, enum sizes must be consistent between LabWindows/CVI and the
compiler for the DLL.
typedef enum {
No_Error,
Device_Busy,
Device_Not_Found
} ErrorType;
The size of ErrorTypeis 2 bytes in Visual C++, whereas it is 1 byte in
LabWindows/CVI. To force LabWindows/CVI to treat ErrorTypeas 2 bytes, add
another enum value explicitly initialized to a 2-byte value, such as the following.
ErrorType_Dummy = 32767
•
If the DLL you are using performs DMA on a buffer you pass to it, you might experience
a problem. The DLL might attempt to lock the buffer in memory by calling the Windows
SDK function GlobalPageLock. GlobalPageLockfails on buffers allocated with the
Watcom mallocfunction that LabWindows/CVI uses in 32-bit mode.
Write the DLL so that if GlobalPageLockfails, the DLL attempts to lock the buffer
with the following code:
int DPMILock (void *buffer, unsigned long size)
{
DWORD base;
unsigned sel, offset;
union _REGS regs;
sel = SELECTOROF(buffer);
offset = OFFSETOF(buffer);
base = GetSelectorBase(sel);
base = base+offset;
regs.x.ax = 0x600; /* DPMI lock memory function */
regs.x.bx = HIWORD(base);
regs.x.cx = LOWORD(base);
regs.x.di = LOWORD(size);
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regs.x.si = HIWORD(size);
int86(0x31, ®s, ®s);
return regs.x.cflag;
}
After the DMA is complete, you must unlock the buffer. You can unlock the buffer using
the DPMILockfunction, if you set regs.x.axto 0x601, instead of 0x600.
•
If you compile the DLL with the /FPior /FPcswitches or with no /FPswitches
(/FPiis the default), the DLL uses the WIN87EM.DLLfloating point emulator.
LabWindows/CVI does not use WIN87EM.DLL. If the DLL uses WIN87EM.DLL, use the
following strategy in the DLL to prevent conflicts:
1. Structure the code so that all functions that perform any floating-point math have
known entry and exit points. Ideally, specify a particular set of exported entry
points as the only ways into the floating-point code.
2. Call the Windows SDK function FPInitin each of these entry points. Store the
previous signal handler in a function pointer.
3. If the DLL has its own exception handler, call signalto register the DLL’s own
signal handler.
4. Perform the floating-point math.
5. Upon exiting through one of the well-defined DLL exit points, call the Windows
SDK function FPTermto restore the previous exception handler and terminate
the DLL’s use of WIN87EM.DLL.
typedef void (*LPFNSIGNALPROC) (int, int);
/* prototypes for functions in WIN87EM.d11 */
LPFNSIGNALPROC PASCAL_FPInit (void);
VOID PASCAL_FPTerm (LPFNSIGNALPROC);
void DllFunction (void)
{
LPFNSIGNALPROC OldFPHandler;
/* save the floating point state, and setup the */
/* floating point exception handler for this DLL.*/
OldFPHandler = _FPInit ();
signal ( SIGFPE, DLLsFPEHandler); /* optional
*/
.
.
.
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/* perform the computations
*/
.
.
.
/* restore the floating point state
_FPTerm (OldFPHandler);
*/
}
Note
If you use Microsoft C to build the DLL, you might get a linker error for an
undefined symbol _acrtused2. This error occurs only in Microsoft C
versions 7.00 and later. Include the following dummy function in your
DLL to fix this error. Also, when linking to the DLL, specify WIN87EM.LIB
as the first library to be linked.
void _acrtused2 (void)
{
}
DLL Glue Code
Because LabWindows/CVI is a 32-bit application, it does not use 16-bit import libraries or
import statements in module definition files. Instead, LabWindows/CVI uses 32-bit DLL glue
code. In some cases, it is sufficient to use glue code that LabWindows/CVI automatically
generates when it loads the DLL. However, you cannot use this method in the following
cases:
•
•
•
The DLL requires special interface functions compiled outside of the DLL.
You expect to pass arrays bigger than 64 K to functions in the DLL.
You pass a pointer to a function in the DLL, and the DLL uses the pointer after the
function returns. For example, you pass an array to a function that starts an asynchronous
I/O operation. The function returns immediately, but the DLL continues to operate on the
array.
•
•
You pass a function pointer to the DLL, and the DLL calls the function later. For example,
the DLL makes a direct callback into 32-bit code.
You pass to the DLL a pointer that points to other pointers. Two examples of pointers that
point to other pointers are an array of pointers and a structure pointer with pointer
members.
•
•
The DLL returns pointers as return values or through reference parameters.
The DLL exports functions by ordinal value only.
If your DLL falls into any of these categories, refer to the DLLs That Cannot Use Glue Code
Generated at Load Time section of this chapter for details on how to proceed. Otherwise, refer
to the DLLs That Can Use Glue Code Generated at Load Time section, also in this chapter.
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DLLs That Can Use Glue Code Generated at Load Time
If your DLL can use glue code generated at load time, LabWindows/CVI automatically
generates the glue code based on the contents of the .hfile it associates with the DLL when
it loads it.
Any functions declared as PASCAL, pascal, or _pascalin the DLL should be declared as
PASCALin the .hfile. LabWindows/CVI ignores the PASCALkeyword except when
generating the glue code.
Use only standard ANSI C keywords in the .hfile. (The keyword PASCALis the only
exception to this rule.) For example, do not use far, near, or huge.
Note
You can create an object module that contains the glue code. If you do so,
LabWindows/CVI can load the DLL faster because it does not have to regenerate
and recompile the glue code. To create the object module, load the .hfile into a
Source window and select Options»Generate DLL Glue Object. If the DLL
pathname is listed in the project, replace it with the object module file. If the DLL
is not listed in the project, but is associated with a .fpfile, make sure the object
module is in the same directory as the .fpfile.
DLLs That Cannot Use Glue Code Generated at Load Time
If your DLL cannot use glue code generated at load time, you must generate a glue code
source file from the DLL include file using the Generate DLL Glue Source command from
the Options menu of a Source window. You must then compile the glue code using the
Watcom compiler to create a .objor .libfile to be loaded with the DLL. If you also have
interface functions that must exist outside the DLL, you must combine them with the glue
code to form the .objor .libfile.
Loading a DLL That Cannot Use Glue Code Generated
at Load Time
If you have a 32-bit Watcom compiled .objor .libfile that contains glue code for a DLL,
LabWindows/CVI must load the .objor .libfile first. For instance, if you want to use
x.dlland x.objin your program, add x.objto the project. Do not add x.dllto the
project. The .objor .libfile causes LabWindows/CVI to load the .dll.
The .objor .libfile must contain the glue code for the DLL. It is the presence of the glue
code that indicates to LabWindows/CVI that a .dllis associated with the .objor .libfile.
When LabWindows/CVI loads the .objor .libfile and finds that it contains glue code, it
first looks for the .dllin the same directory as the .objor .libfile. If it cannot find
the .dll, LabWindows/CVI looks for it using the standard Windows DLL search algorithm.
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Also, you can create a .pthfile in the same directory as the .objor .libfile with the same
base name. The .pthfile must contain a simple filename or a full pathname of the DLL. If it
is a simple filename, LabWindows/CVI uses the standard Windows DLL search algorithm.
You can generate the DLL glue source file by opening the .hfile for the DLL in a Source
window and selecting Generate DLL Glue Source from the Options menu. This command
prompts you for the name of a .hfile. It puts the glue code in a .cfile with the same path and
base name as the .hfile. You must modify this .cfile as this section describes and compile
it using the Watcom compiler. Refer to the Using 32-Bit Watcom Compiled Modules
under Windows 3.1 section of this chapter for information on how to use the Watcom
compiler with LabWindows/CVI.
If any of the functions in the DLL are declared as PASCAL, pascal, or _pascal, you must
declare them as PASCALin the .hfile you use to generate the glue code. LabWindows/CVI
ignores the PASCALkeyword except for the purposes of generating the glue code. The stub
function in the glue code is not declared as PASCAL. If you include this .hfile in the glue
code, the Watcom compiler flags as an error the inconsistency between the declaration of the
function in the .hfile and the definition of the stub function. If you include it in other modules
you compile under Watcom, calls to the function erroneously compile as if the function were
PASCAL. You have two options:
•
Have two separate .hfiles, one that includes the PASCALkeyword and one that does not.
Use the one that does include the PASCALkeyword to generate the glue code only.
•
Use conditional compilation so that Watcom ignores the PASCALmacro when it
compiles.
Only use standard ANSI C keywords in the .hfile. The keyword PASCALis the only
exception to this rule. For example, do not use far, near, or huge.
If the DLL Requires a Support Module outside the DLL
Support modules contain special interface functions that the DLL uses but that exist outside
of the DLL. If you are unsure whether the DLL requires a support module, try to build a
project in LabWindows/CVI with the DLL in the project list. If link errors exist in the form
of unresolved references, the DLL requires special interface functions. Get the source code
for the interface functions, add it to the glue code, and compile using the Watcom compiler.
If You Pass Arrays Bigger Than 64 K to the DLL
If you pass the DLL any arrays bigger than 64 K, you must modify the glue code source file.
For example, suppose you have a function in the DLL with the following prototype:
long WriteRealArray (double realArray[], long numElems);
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In the glue code generated by LabWindows/CVI, there is a declaration of WriteRealArray
like that shown in the following example.
long WriteRealArray (double realArray[], long numElems)
{
long retval;
unsigned short cw387;
cw387 = Get387CW();
retval = (long)
InvokeIndirectFunction (__static_WriteRealArray, realArray,
numElems);
Set387CW (cw387);
return retval;
}
Note
The lines of code referencing cw387are necessary only if the DLL function
performs floating point operations. They are innocuous and execute quickly, so
LabWindows/CVI adds them to the glue code automatically. If the DLL function
does not perform floating point operations, you can remove these lines.
If realArraycan be greater than 64 K, you must modify the interface routine as shown.
long WriteRealArray (double realArray[], long numElems)
{
long retval;
unsigned short cw387;
DWORD size;
DWORD alias;
size = numElems * sizeof(double);
if (Alloc16BitAlias (realArray, size, &alias) <0)
return <error code>;
cw387 = Get387CW();
retval = (long)
InvokeIndirectFunction (__static_WriteRealArray, alias,
numElems);
Set387CW (cw387);
Free16BitAlias (alias, size);
return retval;
}
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You must also modify the call to GetIndirectFunctionHandlefor WriteRealArrayas
shown in the following code:
if (!(__static_WriteRealArray = GetIndirectFunctionHandle
(fp, INDIR_PTR, INDIR_WORD, INDIR_ENDLIST)))
by changing INDIR_PTRto INDIR_DWORD.
If the DLL Retains a Buffer after the Function Returns
(an Asynchronous Operation)
If the DLL retains a buffer after the function returns, you must modify the glue code source
file. Suppose two functions exist. WriteRealArrayAsyncoperates just like
WriteRealArray, except that it returns before it completes writing the real array.
ClearAsyncWriteterminates the asynchronous I/O. The glue code interface functions for
WriteRealArrayAsyncand ClearAsyncWriteshould be modified to resemble the
following example.
static DWORD gAsyncWriteAlias, gAsyncWriteSize;
long WriteRealArrayAsync (double realArray[], long numElems)
{
long retval;
unsigned short cw387;
DWORD size;
DWORD alias;
size = numElems * sizeof(double);
if (Alloc16BitAlias (realArray, size, &alias) < 0)
return <error code>;
cw387 = Get387CW();
retval = (long)
InvokeIndirectFunction (__static_WriteRealArrayAsync, alias,
numElems);
Set387CW (cw387);
if (IsError (retval)) /* replace with macro to check if */
/* retval is error
Free16BitAlias (alias, size);
else {
*/
gAsyncWriteAlias = alias;
gAsyncWriteSize = size;
}
return retval;
}
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long ClearAsyncWrite (void)
{
/* because this does no floating point, you can remove */
/* the cw387 code
long retval;
*/
retval = (long) InvokeIndirectFunction(__static_ClearAsyncWrite);
if (!IsError (retval)) /* replace with macro to check if */
/* retval is error
if (gAsyncWriteAlias != 0) {
*/
Free16BitAlias (gAsyncWriteAlias,gAsyncWriteSize);
gAsyncWriteAlias = 0;
gAsyncWriteSize = 0;
}
return retval;
}
You can terminate LabWindows/CVI programs in the middle of execution and then re-run
them. When you terminate the program, you should also terminate the asynchronous I/O. You
can arrange to be notified of changes in the run state by including a function with the name
RunStateChangeCallbackin the .objor .libfile associated with the DLL. You can add
this function to the glue code file. Refer to the Notification of Changes in Run State section
of Chapter 2, Using Loadable Compiled Modules, of this manual for a complete description
of the run state change notification. In the example we have been discussing, you should add
the following code.
#include "libsupp.h"
void CVICALLBACK __RunStateChangeCallback (int newState)
{
if (newState == kRunState_Stop)
ClearAsyncWrite ();
}
If the DLL calls directly back into 32-bit code, you must modify the glue code source file.
You can call functions defined in 32-bit source code directly from a DLL. Although this
method is not as straightforward as Windows messaging, it is not subject to the latencies of
Window messaging. For more information about Windows messaging, refer to the
Recognizing Windows Messages Passed from a DLL section of this chapter.
Note
If you need direct callbacks to occur at interrupt time because the latency of
Windows messaging is interfering with your application, contact National
Instruments for assistance.
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You cannot pass pointers to 32-bit functions directly into 16-bit DLLs. The Windows SDK
interface for this is very complex. Generate DLL Glue Source does not generate this code
for you. You must write your own glue code for passing function pointers to and from a DLL,
and add it to the file that Generate DLL Glue Source generates.
Suppose a DLL contains the following functions:
long (FAR*savedCallbackPtr) (long);
long FAR InstallCallback(long (FAR*callbackPtr) (long))
{
savedCallbackPtr = callbackPtr;
}
long InvokeCallback(long data)
{
return (*savedCallbackPtr)(data);
}
After you use the Generate DLL Glue Source command to generate the glue code for these
functions, you must modify the code as follows.
Note
Because direct callbacks must be declared far, and LabWindows/CVI cannot
compile farfunctions, you must declare a farfunction in the glue code and pass
it to the DLL. This farfunction calls the actual user function.
#undef MakeProcInstance
#undef FreeProcInstance
/* Use version that does not */
/* convert pointer. */
/* Use version that does not */
/* convert pointer. */
typedef struct { /* Holds resources required to register*/
/* the callback. */
int UserDefinedProcHandle;
CALLBACKPTR proc16;
FARPROC proc16Instance;
} CallbackDataType;
static CallbackDataType CallbackData;
static long (*UsersCallback)(long);
/* Define a 32-bit far callback whose address is passed to */
/* the DLL. It calls your function using function pointer */
/* stored in UsersCallback.
*/
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static long FAR CallbackHelper(long data)
{
return (*UsersCallback)(data);
}
/* Modified glue code for the function that installs the */
/* callback.
*/
long InstallCallback(long (*callback)(long))
{
long retval;
unsigned short cw387;
UsersCallback = callback; /* Store CVI 32-bit pointer */
/* in static variable.
*/
/* Create a 16-bit thunk for the 32-bit far function
/* CallbackHelper
*/
*/
if ((CallbackData.UserDefinedProcHandle =
GetProcUserDefinedHandle()) == 0)
return FALSE;/* Too many callbacks installed
/* or handles not freed.
*/
*/
if (DefineUserProc16(CallbackData.UserDefinedProcHandle,
(PROCPTR) CallbackHelper, UDP16_DWORD,
UDP16_CDECL, UDP16_ENDLIST))
goto failed;
if (!(CallbackData.proc16 =
GetProc16((PROCPTR)CallbackHelper,
CallbackData.UserDefinedProcHandle)))
goto failed;
CallbackData.proc16Instance =
MakeProcInstance(CallbackData.proc16,
GetTaskInstance());
cw387 = Get387CW();
retval = (long)
InvokeIndirectFunction(__static_InstallCallback,
CallbackData.proc16Instance);
Set387CW(cw387);
return retval;
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failed:
FreeCallbackResources();
return FALSE;
}
/* Call this function after unregistering the callback. */
void FreeCallbackResources(void)
{
if (CallbackData.proc16Instance) {
FreeProcInstance(CallbackData.proc16Instance);
CallbackData.proc16Instance = 0;
}
if (CallbackData.proc16) {
ReleaseProc16(CallbackData.proc16);
CallbackData.proc16 = 0;
}
if (CallbackData.UserDefinedProcHandle) {
FreeProcUserDefinedHandle(CallbackData.UserDefinedProcHandle);
CallbackData.UserDefinedProcHandle = 0;
}
}
If the DLL Returns Pointers
DLLs return pointers that fall into the following two classes.
•
Pointers to memory that LabWindows/CVI allocates, that you pass into the DLL, and that
the DLL later returns
You must map these pointers back into normal 32-bit pointers that you can use in
LabWindows/CVI code. Use the function MapAliasToFlatto convert these pointers.
•
Pointers to memory that a DLL allocates
Because these pointers point to memory that is not in the LabWindows/CVI flat address
space, you cannot map them back into the normal 32-bit pointers that LabWindows/CVI
uses. You can access them in Watcom object code by first converting them to 32-bit far
pointers using the function MK_FP32.
To access them in LabWindows/CVI source code you must copy the data into a buffer
you allocate in LabWindows/CVI. Notice that you cannot pass 16- or 32-bit far pointers
to LabWindows/CVI library functions, and that LabWindows/CVI does not provide
access to the Watcom string and memory buffer manipulation functions that take far
pointers as arguments. You must write the loops to copy the data.
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Case 1
Assume the DLL has the following function:
char *f(char *ptr)
{
sprintf(ptr, "hello");
return ptr;
}
Then assume that a program in LabWindows/CVI uses the function fas follows:
char buffer[240];
char *bufptr;
bufptr = f(buffer);
printf("%s", bufptr);
You would have to modify the glue code as shown here:
char * f(char *ptr)
{
char * retval;
unsigned short cw387;
cw387 = Get387CW();
retval = (char *) InvokeIndirectFunction(__static_f, ptr);
Set387CW(cw387);
retval = MapAliasToFlat(retval); /* Add this line to */
/* glue code.
*/
return retval;
}
Case 2
Assume the DLL has the following function:
char *f(void)
{
char *ptr;
ptr = malloc(100);
sprintf(ptr, "hello");
return ptr;
}
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Then assume that a program in LabWindows/CVI uses the function fas follows:
char *bufptr;
bufptr = f();
printf("%s", bufptr);
You would have to modify the glue code as shown here:
char * f(char *ptr)
{
char *retval;
unsigned short cw387;
char *ptr, *tmpPtr, _far *farPtr32, _far *tmpFarPtr32;
int i;
cw387 = Get387CW();
retval = (char *) InvokeIndirectFunction(__static_f, ptr);
Set387CW(cw387);
/* convert the 16 bit far pointer to a 32 bit far pointer*/
farPtr32 = MK_FP32(retval);
tmpFarPtr32 = farPtr32;
/* Calculate the length of the string. Cannot call strlen*/
/* because it does not accept far pointers.
*/
i = 0
while (*tmpFarPtr32++)
i++;
/* Allocate buffer from CVI memory and copy in data.
*/
if ((ptr = malloc(i + 1)) != NULL) {
tmpFarPtr32 = farPtr32;
tmpPtr = ptr;
while (*tmpPtr++ = *tmpFarPtr32++);
}
return ptr;
}
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If a DLL Receives a Pointer that Points to Other Pointers
Assume the following DLL functions:
int f(char *ptrs[]);
struct x {
char *name;
};
int g(struct x *ptr);
For the function f, the glue code that LabWindows/CVI generates converts the pointer to the
array ptrsto a 16-bit far pointer when you pass it to the DLL function, but does not convert
the pointers inside the array (ptrs[0], ptrs[1], ...). Similarly, for the function g, the
glue code that LabWindows/CVI generates converts the pointer to the structure (ptr), but not
the pointer inside the structure (name).
If your DLL has functions with these types of parameters, then your DLL cannot use glue
code automatically generated at load time. You can use the Generate DLL Glue Source
command to generate glue code and then modify it in the following manner.
1. Before the call to InvokeIndirectFunction,
a. Save the hidden pointer in a local variable.
b. Replace the hidden pointer with a 16-bit alias by calling Alloc16BitAlias.
2. After the call to InvokeIndirectFunction,
a. Free the 16-bit alias by calling Free16BitAlias.
b. Restore the hidden pointer with the value you saved in step 1.
For the functions fand g, the glue code that LabWindows/CVI generates looks like the
following excerpt:
int f(char **ptrs)
{
int retval;
unsigned short cw387;
cw387 = Get387CW();
retval = (int) InvokeIndirectFunction(__static_f, ptrs);
Set387CW(cw387);
return retval;
}
int g(struct x *ptr)
{
int retval;
unsigned short cw387;
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cw387 = Get387CW();
retval = (int) InvokeIndirectFunction(__static_g, ptr);
Set387CW(cw387);
return retval;
}
After you make the necessary changes, the code should appear as follows:
/* Assume NUM_ELEMENTS is the number of pointers in the input */
/* array. Assume ITEM_SIZE is the number of bytes pointed
*/
/* to by each pointer. If you do not know ITEM_SIZE, but you */
/* know that it is 64K or less, you can use 64K as ITEM_SIZE. */
int f(char **ptrs)
{
int retval;
unsigned short cw387;
int i;
char *savedPointers[NUM_ELEMENTS];
/* change the pointers to 16-bit far pointers */
for (i = 0 ; i < NUM_ELEMENTS; i++) {
savedPointers[i] = ptrs[i];
if (Alloc16BitAlias(ptrs[i], ITEM_SIZE, &ptrs[i]) == -1) {
/* failed to allocate an alias; restore */
/* pointers.
while (i--)
*/
ptrs[i] = savedPointer[i];
return <error code>;
}
}
cw387 = Get387CW();
retval = (int) InvokeIndirectFunction(__static_f, ptrs);
Set387CW(cw387);
/* Restore the pointers. */
for (i = 0 ; i < NUM_ELEMENTS; i++) {
Free16BitAlias(ptrs[i], ITEM_SIZE);
ptrs[i] = savedPointers[i];
}
return retval;
}
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int g(struct x *ptr)
{
int retval;
unsigned short cw387;
char *savedPointer;
savedPointer = ptr->name;
if (Alloc16BitAlias(ptr->name, ITEM_SIZE, &ptr->name) == -1)
return <error code>;
cw387 = Get387CW();
retval = (int) InvokeIndirectFunction(__static_g, ptr);
Set387CW(cw387);
Free16BitAlias(ptr->name, ITEM_SIZE);
ptr->name = savedPointer;
return retval;
}
DLL Exports Functions by Ordinal Value Only
If your DLL does not export its functions by name, but by ordinal number only, you must
modify the GetProcAddress function calls in the glue code. Instead of passing the name of
the function as the second parameter, pass PASS_WORD_AS_POINTER(OrdinalNumber),
where OrdinalNumberis the ordinal number for the function. For example, if the ordinal
number for the function InstallCallbackis 5, change the glue code as follows.
Generated Glue Code:
if (!(fp = GetProcAddress(DLLHandle,"InstallCallback")))
{
funcname = "_InstallCallback";
goto FunctionNotFoundError;
}
Change to:
if (!(fp = GetProcAddress(DLLHandle, PASS_WORD_AS_POINTER(5))))
{
funcname = "_InstallCallback";
goto FunctionNotFoundError;
}
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Recognizing Windows Messages Passed from a DLL
The normal way of communicating with a DLL is to call functions in the DLL. However,
cases exist where other communication methods are necessary. The most typical case is that
of an interrupt service routine in a DLL that must notify the application that the interrupt
occurred. In cases like this, you must communicate with the DLL through a callback function.
LabWindows/CVI recognizes messages posted by a DLL through the Windows SDK
function PostMessage, and can initiate a user callback function. This method is useful
for hardware interrupts, but it is subject to the latency associated with Windows messaging.
LabWindows/CVI uses RegisterWinMsgCallback, UnRegisterWinMsgCallback, and
GetCVIWindowHandleto recognize Windows messages from a DLL. You can call these
functions from a module compiled in Watcom or from source code.
For complete information on these functions, refer to the function descriptions in Chapter 4,
User Interface Library Reference, of the LabWindows/CVI User Interface Reference Manual.
To use these functions, call RegisterWinMsgCallbackand GetCVIWindowHandle. Pass
their return values, the message number and the window handle, to the DLL. When the DLL
sends a message, it calls PostMessagewith these values. When LabWindows/CVI receives
the message, it calls the callback function.
Note
LabWindows/CVI can receive the message only when it is processing events.
LabWindows/CVI processes events when it is waiting for user input. If the
program you run in LabWindows/CVI does not call RunUserInterface,
GetUserEvent, or scanf, or if it does not return from a User Interface Library
callback, events will not be processed. You can remedy this in the program by
periodically calling the User Interface Library function ProcessSystemEvents.
Creating 16-bit DLLs with Microsoft Visual C++ 1.5
Be sure to consider the following issues or project options when you create a DLL with
Microsoft Visual C++ 1.5:
•
•
•
•
Every function you call from outside the DLL must be far, exported, and must load the
data segment into the DS register. The function must load the DS register if you want to
use any non-local variables in a function.
Use the large or huge memory model. The savings you gain by using smaller memory
models is not worth having to use the farkeyword throughout your code. This project
option is in Compiler»Memory Model»Segment Setup.
You can make the compiler load the data segment into the DS register automatically by
using the SS!=DS, DS loaded on function entry project option in Compiler»Memory
Model»Segment Setup.
If you try to use the optimize entry code option (/GD), by selecting
Compiler»Windows»Prolog/Epilog»Generate Prolog/Epilog For, it conflicts with the
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/Auoption. You can either not use this option by setting it to None, or insert __loadds
in front of every function you export from the DLL.
•
•
•
You can make the compiler export a function by inserting __exportbetween the return
type and the function name, or by adding the function name to the exports section of the
.deffile.
If you add the function name to the exports section of the .deffile, remember to convert
the name to all caps if you use the PASCALcalling convention, or pre-append an
underscore if you use the CDECLcalling convention.
Byte align structure members by choosing 1 Byte for the Options»Project»Compiler»
Code Generation»Struct Member Byte Alignment.
Creating 16-bit DLLs with Borland C++
Consider the following issues or project options when you create a DLL with
Borland C++ 4.x:
•
•
•
•
Every function you call from outside the DLL must be far, exported, and must load the
data segment into the DS register. The function must load the DS register if you want to
use any non-local variables in a function.
Use the large or huge memory model. The savings you gain by using smaller memory
models is not worth having to use the farkeyword throughout your code. This project
option is in 16-bit Compiler»Memory Model»Mixed Model Override.
You can make the compiler load the data segment into the DS register by setting the
project option 16-bit Compiler»Memory Model»Assume SS Equals DS to Never, or
by inserting _loaddsin front of every function you export from the DLL.
You can make the compiler export a function by inserting _exportbetween the return
type and the function name, adding the function name to the exports section of the .def
file, or setting the option 16-bit Compiler»Entry/Exit Code»Windows DLL, all
functions exportable.
•
If you add the function name to the exports section of the .deffile, remember to convert
the name to all caps if you use the PASCALcalling convention, or pre-append an
underscore if you use the CDECLcalling convention. Also, set the Generate Underscores
option in Compiler»Compiler Output.
•
•
•
Turn off the Allocate Enums as Ints option in Compiler»Code Generation.
Set the Data Alignment options to Byte in 16-bit Compiler»Processor.
Turn off the Case Sensitive Link and Case Sensitive Exports and Imports options in the
Linker»General.
•
Do not use the Linker Goodies options in Linker»16-bit Linker.
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DLL Search Precedence
LabWindows/CVI finds a DLL file in the following ways for Windows 3.1:
•
If the .dllfile is associated with a .fpfile, LabWindows/CVI uses the following search
precedence to find the DLL.
1. If a .pthfile with the same full path name as the .fpfile is in the project,
LabWindows/CVI uses the standard Windows DLL search algorithm. The .pth
file must contain the name of the .dllfile, such as mystuff.dll. It must
contain an absolute path or a simple filename.
2. If a .dllfile with the same full path name as the .fpfile is in the project,
LabWindows/CVI uses the absolute path of the .dllfile in the project to load
the .dllfile.
3. If a .pthfile with the same base name as the .fpfile is in the same directory as
the .fpfile and a .libor .objfile of the same base name does not exist in the
same directory, LabWindows/CVI uses the standard Windows DLL search
algorithm. The .pthfile must contain the name of the .dllfile, such as
mystuff.dll. It must not contain any directory names or slashes.
4. If a .dllfile with the same base name as the .fpfile is in the same directory as
the .fpfile, LabWindows/CVI loads the .dllfile as long as no .lib, .obj,
or .pthfile of the same base name appears in the same directory.
5. If a .pthor .dllfile does not appear in the same directory as the .fpfile,
LabWindows/CVI uses the standard Windows search algorithm to look for a
DLL with the same base name as the .fpfile. Thus, if a DLL with the same base
name is in the windowsor windows\systemdirectory or a directory listed in
your PATHenvironment variable, LabWindows/CVI finds it.
DLLs for VXIplug&play drivers are not in the same directory as the .fpfiles, but the
directory that contains the DLL is listed in the PATHenvironment variable. Therefore,
Step 5 makes it easier for you to use VXIplug&play instrument driver DLLs in
LabWindows/CVI for Windows 3.1.
•
If the .dllfile is not associated with a .fpfile, LabWindows/CVI uses the following
search precedence to find the DLL:
1. If a .pthfile is in the project list, LabWindows/CVI uses the standard Windows
DLL search algorithm. The .pthfile must contain the name of the .dllfile,
such as mystuff.dll. It must contain an absolute path or a simple filename.
2. If the .dllfile is in the project list, then LabWindows/CVI uses the absolute
pathname to find the .dllfile.
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•
If you call LoadExternalModuleon the .dllfile, then
–
–
If you specify it with an absolute pathname, LabWindows/CVI loads that file.
If you specify it with a relative pathname, LabWindows/CVI searches for the .dll
file in the following places and order indicated.
1. In the project list.
2. In the directory in which the project file is located.
3. Among other modules already loaded.
4. In the directories specified in the documentation for the Windows SDK
LoadLibraryfunction. In this case, the include file for the DLL must be in
the project or in one of the include paths you specify in the Include Paths
command in the Options menu of the Project window.
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5
UNIX Compiler/Linker Issues
This chapter describes the kinds of compiled modules available under LabWindows/CVI for
UNIX and includes programming guidelines for modules you generate with external
compilers.
Calling Sun C Library Functions
You can call functions in the Sun Solaris C libraries from source code in LabWindows/CVI.
LabWindows/CVI automatically links your program to the following static libraries, located
in the /usr/libdirectory, when you build the project.
Solaris 1: libm.a, libc.a
Solaris 2: libsocket.a, libnsl.a, libintl.a, libm.a, libc.a
When you create a standalone executable, LabWindows/CVI invokes the Sun Solaris link
editor (ld) to link your program to the LabWindows/CVI dynamic library and to the system
libraries. By default, the Sun Solaris link editor uses the dynamic versions of the libraries.
LabWindows/CVI passes the following linking options to the Sun Solaris link editor:
Solaris 1: -lm -ldl -lc
Solaris 2: -lsocket -lnsl -lintl -lm -lthread -lc
In general, you can use the header files that Sun provides for these libraries in the
/usr/includedirectory. For the ANSI C functions, however, use the header files that come
with LabWindows/CVI.
Restrictions on Calling Sun C Library Functions
You cannot call any Sun C Library function that uses data types incompatible with the
LabWindows/CVI compiler or libraries. In particular, you must not call functions that use the
longdoubledata type. In LabWindows/CVI the longdoubledata type has 8 bytes, but the
Sun libraries expect a 16-byte object.
Under Solaris 2, you must not call any function that uses the longlongdata type.
LabWindows/CVI does not recognize this non-ANSI type.
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In the LabWindows/CVI development environment, you can link your programs to static
libraries, but not to shared libraries. If you have to use a shared library, you must use the Sun
Solaris linker (ld) to build your application. Refer to the Creating Executables that Use the
LabWindows/CVI Libraries section later in this chapter for more information on using
external compilers and the Sun linker.
If you have both shared and static versions of a library, you can develop and debug your
application in the LabWindows/CVI development environment using the static version of the
library. You can then create your final executable with the Sun linker using the shared version
of the library.
Using dlopen
The Sun Solaris dlopenfunction allows you to load shared libraries from your program
dynamically. Although this function can work in some cases when running in
LabWindows/CVI, it can make LabWindows/CVI unstable. If you use dlopento load shared
libraries in a program you run in LabWindows/CVI, the shared libraries might link to the
system libraries the LabWindows/CVI environment uses. As a result, functions in the shared
library might modify the LabWindows/CVI environment and cause unpredictable behavior.
The LabWindows/CVI Run-Time Engine
as a Shared Library
The LabWindows/CVI development environment contains many built-in libraries such as the
User Interface Library and Utility Library. LabWindows/CVI also provides these libraries in
the form of a standalone shared library called the LabWindows/CVI Run-time Engine. All
executables that call LabWindows/CVI library functions use the Run-time Engine shared
library. This is true whether you build the executable in the LabWindows/CVI development
environment or with an external compiler and the Sun Solaris linker.
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Creating Executables that Use the
LabWindows/CVI Libraries
You can build executables that use the LabWindows/CVI libraries in two ways:
•
You can build an executable in the LabWindows/CVI development environment by
selecting the Create Standalone Executable command in the Build menu of the Project
window. When you do so, LabWindows/CVI invokes the Sun Solaris linker (ld) to link
your programs to the Run-time Engine shared library.
•
You can use an external compiler and linker to create an executable that uses the
Run-time Engine shared library. Use the Generate Makefile command in the Build menu
of the Project window to generate a UNIX makefile that corresponds to the currently
loaded project and libraries. The makefile invokes an external compiler to compile your
source files, and then it invokes the Sun Solaris linker (ld) to link the compiled files with
the Run-time Engine shared library.
Compatible External Compilers
You can use the following external ANSI C compilers to compile source files for linking with
the LabWindows/CVI Run-time Engine shared library.
•
•
GNU C Compiler (gcc)
Sun C Compiler (ccand acc)
Note
Under Solaris 2.4, when linking the LabWindows/CVI Shared Library with
external ANSI C compiler, the compiler displays a warning that states the shared
library has an invalid type. You can ignore this warning.
Static and Shared Versions of the ANSI C and Other Sun Libraries
When you build a project for execution in the LabWindows/CVI development environment,
LabWindows/CVI links your program to the static versions of the Sun Solaris libraries
(libc.aand libm.a). On the other hand, when you create a standalone executable in the
LabWindows/CVI development environment, LabWindows/CVI invokes the Sun Solaris link
editor (ld) to link your program to the shared versions of the libraries (libc.soand
libm.so). Similarly, when you generate a UNIX makefile by invoking the Generate
Makefile command from the Build Menu of the Project window, the makefile contains linker
commands to use the shared versions of the libraries.
Thus, when you run your programs as executables, you use a different version of the Sun
libraries (including the ANSI C library) than when you run them in the LabWindows/CVI
development environment. Your program might exhibit slightly different behavior as a
standalone executable than when run in the development environment.
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Non-ANSI Behavior of Sun Solaris 1 ANSI C Library
The C library that comes with Sun Solaris 1 (SunOS 4.1.x) does not comply with the ANSI C
•
•
Some ANSI C functions are missing from the library.
Some library functions have different behavior than the ANSI standard specifies.
LabWindows/CVI corrects these problems by adding a library, libcfix.a, that
replaces and supplements the Sun Solaris library as necessary. The Solaris 1 ANSI C Library
Implementation section contains more information about how LabWindows/CVI provides an
ANSI C library on Solaris 1.
LabWindows/CVI Implements printf and scanf
Although the Sun Solaris libraries provide the ANSI C family of functions for formatted input
and output (scanf, printf, and others), LabWindows/CVI provides special versions of
these functions for the following reasons:
•
•
•
The LabWindows/CVI versions of these functions provide run-time error checking not
available with Sun Solaris versions.
The Sun Solaris 1 version of these functions do not comply fully with the ANSI C
standard.
The Sun Solaris versions of these functions do not work with the LabWindows/CVI
implementation of the long double data type.
For standalone executables, these functions come in a separate static library,
libcviprintf.a, in the libsubdirectory of the LabWindows/CVI installation directory.
When you create an executable in LabWindows/CVI, LabWindows/CVI links your program
to this static library.
Main Function Must Call InitCVIRTE
If your program calls any functions from the LabWindows/CVI libraries, you must call
InitCVIRTEto initialize the libraries from the executable. This function takes three
arguments. The first and third arguments to this function must always be 0 for UNIX
applications. The second must be the same value as the second parameter of your main
function. InitCVIRTEreturns 0 if it fails.
You do not have to call InitCVIRTEwhen you run your program in the LabWindows/CVI
development environment because LabWindows/CVI always initializes the libraries.
However, if you do not call InitCVIRTE, your executable cannot work. For this reason,
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National Instruments recommends that you always include source code similar to the
following example in your program.
int main(int argc, char *argv[])
{
if (InitCVIRTE(0, argv, 0) == 0) {
return 1;/* Failed to initialize */
}
/* your program code here */
}
If you pass NULLfor the second argument to InitCVIRTE, your program might still work,
but with the following limitations:
•
Your executable cannot accept the -displaycommand line argument. As a result, you
cannot specify an X display on the command line for your program to use. You still can
use the DISPLAYenvironment variable to specify a different X display.
• LoadPanel, LoadExternalModule, DisplayImageFile, SavePanelState,
RecallPanelState, and other functions that normally use the directory of the
executable to search for files, use the current working directory instead. If you run the
executable from a directory other than the one that contains your executable, some of
these functions might fail to find files.
Run State Change Callbacks Are Not Available in Executables
When you use a compiled module in LabWindows/CVI, you can arrange for
LabWindows/CVI to notify it of a change in execution status (start, stop, suspend, resume).
You do this through a function called __RunStateChangeCallback. The Notification of
Changes in Run State section, in Chapter 2, Using Loadable Compiled Modules, describes
this in detail.
The run state change callback capability in LabWindows/CVI is necessary because when you
run a program in the LabWindows/CVI development environment, it executes as part of the
LabWindows/CVI process. When your program terminates, the operating system does not
release resources as it does when a process terminates. LabWindows/CVI releases as many
resources as it can, but your compiled module might have to do more. Also, if the program
suspends for debugging purposes, your compiled module might have to disable interrupts.
When you run a standalone executable, it always executes as a separate process. Thus, the run
state change callback facility is not necessary and does not work. External compilers report
link errors when you define __RunStateChangeCallbackin more than one object file. If
you require a run state change callback in a compiled module that you intend to use both in
LabWindows/CVI and an external compiler, National Instruments recommends that you put
the callback function in a separate source file and create a library (.a) instead of an object file.
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Using Externally Compiled Modules
In general, you can load objects compiled with the Sun compilers and the GNU gcccompiler
into LabWindows/CVI, with a few restrictions.
Restrictions on Externally Compiled Modules
You can use externally compiled modules with the following restrictions:
•
The objects must not use any data types that are incompatible with the LabWindows/CVI
compiler or libraries. Incompatible data types include the following:
– longdoublewith any Sun compilers. A Sun compiler implements longdouble
as a 16-byte object, but LabWindows/CVI implements it as an 8-byte object.
– longlongwith the Solaris 2 Sun compiler. LabWindows/CVI does not support this
non-ANSI type.
–
Any enumeration type. Many compilers implement enumeration types with different
sizes and values.
•
You cannot load a Solaris 2 object file when you run LabWindows/CVI under Solaris 1.
However, you can load Solaris 1 objects when you run under Solaris 2.
Compiling Modules With External Compilers
You can compile external modules using LabWindows/CVI header files instead of the headers
the compiler supplies. To compile this way, you must define the preprocessor macro
_NI_sparc_ to the value 1for Solaris 1 or to the value 2for Solaris 2.
When using the Sun ANSI C compiler, use the -Iflag to add the LabWindows/CVI include
directory to the search list, as shown in the following command lines:
Solaris 1: acc -Xc -I/home/cvi/include -D_NI_sparc_=1 -c mysource.c
Solaris 2: cc -Xc -I/home/cvi/include -D_NI_sparc_=2 -c mysource.c
When using the GNU compiler, use the -nostdincflag to disable the standard include files
and the -Iflag to add the LabWindows/CVI include directory to the search list. Also, you
must use the -ansiflag. For example, to compile the file mysource.cusing
LabWindows/CVI headers under Solaris 1, use the following command line.
gcc -ansi -nostdinc -I/home/cvi/include -D_NI_sparc_=1 -c mysource.c
You might see warnings about conflicting types for the built-in functions memcmpand
memcpy, but you can ignore them.
Note
These examples assume that /home/cvi/includeis the LabWindows/CVI
header files directory. The actual path depends on how you install your copy of
LabWindows/CVI.
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You cannot use the non-ANSI C Sun compiler ccbecause it does not recognize some ANSI C
constructs in the header files, such as function prototypes and the keywords const, void, and
volatile.
Locking Process Segments into Memory Using plock()
You can use the UNIX function plockto lock the text and data segments of your program
into memory. However, this function locks all segments of the LabWindows/CVI process, not
just the segments associated with your program. Also, because the text segments of
LabWindows/CVI programs actually reside in the data segment of the LabWindows/CVI
process, you must lock both text and data segments, using plock(PROCLOCK), in order to
lock all text into memory.
Note
Your LabWindows/CVI process must have superuser privileges to use the plock
function.
UNIX Asynchronous Signal Handling
The following signals have special meaning in LabWindows/CVI:
•
SIGPOLL (SIGIO) and SIGPIPE—The LabWindows/CVI TCP Library installs
signal handlers for SIGPOLL(SIGIO) and SIGPIPE. If you use the TCP Library and you
want to install handlers for these signals, you must call the LabWindows/CVI handlers
when your handlers are called. If you attempt to set the signal handler to SIG_DFLfor
these signals while running in the LabWindows/CVI environment, LabWindows/CVI
restores its own handlers.
•
SIGINT and SIGQUIT—Normally, the operating system generates these two signals
when you type certain keystrokes (<Ctrl-C> and <Ctrl-\>) in the window from which
you invoke LabWindows/CVI. If one of these signals occurs while your program is
running and you have not installed a handler for it, LabWindows/CVI suspends
your program the next time it calls a function that processes events (such as
ProcessSystemEvents). If your program does not call any event-processing
functions, it continues to run.
•
•
SIGTERM—LabWindows/CVI treats SIGTERMas a stronger version of SIGINTand
SIGQUIT. If this signal occurs while your program is running and you have not installed
a handler for it, LabWindows/CVI terminates the program, gives you a chance to save
your files, and exits. If SIGTERMoccurs when no program is running, LabWindows/CVI
exits immediately.
SIGBUS, SIGFPE, SIGILL, and SIGSEGV—These signals exist to allow for
hardware exceptions. Because execution cannot continue beyond the instruction that
caused the exception, LabWindows/CVI always catches these signals. If this signal
occurs while your program is running, LabWindows/CVI reports a fatal run-time error
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UNIX Compiler/Linker Issues
and suspends operation at the statement that caused the exception. If this signal occurs
when no program is running, LabWindows/CVI exits immediately.
You cannot use signal, sigaction, sigset, or sigvecto make your program ignore the
signals this section lists.
Note
If your program begins to loop indefinitely, you can often suspend execution by
sending a signal to the LabWindows/CVI process as follows:
1. Use the pscommand to identify the process number of LabWindows/CVI.
2. Send the kill -SIGNAL pidcommand to that process. For example, if the
LabWindows/CVI process number is 3478, the command kill -INT 3478
sends the SIGINTsignal to LabWindows/CVI. When you want to suspend
execution of your program in LabWindows/CVI, try using SIGINTor SIGQUIT.
If sending the SIGINTor SIGQUITsignal fails, you must use the stronger
SIGTERMsignal, which terminates not just your program but also
LabWindows/CVI.
Note
Some signals can cause LabWindows/CVI to dump core you are running a
program that does not install handlers for them.
Solaris 1 ANSI C Library Implementation
The C library that comes with Sun Solaris 1 (SunOS 4.1.x) does not comply with the ANSI C
standard as follows:
•
•
Some ANSI C functions are missing from the library.
Some library functions have different behavior than the ANSI standard specifies.
LabWindows/CVI corrects these problems by linking your programs to a supplemental C
library libcfix.a, which is in the libsubdirectory of the LabWindows/CVI installation
directory. This library contains replacement functions for some Sun Solaris functions and for
the ANSI functions that are not available in the Sun Solaris library. The names of the
replacement functions differ from the Sun Solaris function names and do not interfere with
programs or libraries that depend upon the non-ANSI behavior of some Sun Solaris functions.
The LabWindows/CVI ANSI header files contain macro definitions for the replacement
functions. When you compile with the LabWindows/CVI headers, your program references
the LabWindows/CVI replacement functions instead of the Sun Solaris versions.
Consider the case of realloc, which LabWindows/CVI replaces with _cvi_realloc. The
Sun Solaris 1 implementation of the reallocfunction fails when the first argument is
NULL. The ANSI standard requires that reallocaccept NULL as a first argument. In the
library libcfix.a, LabWindows/CVI defines _cvi_realloc, which treats a NULL
argument as the ANSI standard prescribes. The LabWindows/CVI header file stdlib.h
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contains the following macro definition so that _cvi_reallocreplaces all references to
reallocin your program.
#define realloc _cvi_realloc
Note
Object files you previously compiled using either older LabWindows/CVI headers
or Sun Solaris headers do not reference the replacement functions. You must
recompile your object files using LabWindows/CVI headers to obtain
ANSI-compliant behavior.
The following lists show the complete contents of the supplemental C library libcfix.a.
Replacement Functions
Name
Header
Non-ANSI Behavior of Sun Version
_cvi_fflush
_cvi_fopen
stdio.h
Does not handle NULL argument properly.
stdio.h
Does not support binary open mode ("b").
Append open mode ("a") incorrect.
_cvi_freopen
_cvi_realloc
_cvi_strtol
_cvi_system
matherr
stdio.h
Same as fopen.
stdlib.h
stdlib.h
stdlib.h
Does not handle NULL argument properly.
Does not set errno to ERANGEon error.
Does not handle NULL argument properly.
Default behavior prints error message.
Additional Functions Not Found in Sun Solaris 1 libc
_assert (used by assert()macro in assert.h)
labs
srand
fsetpos
fgetpos
atexit
difftime
div
ldiv
fpos
memmove
raise
rand
strerror
strtoul
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Incompatibilities among LabWindows/CVI,
Sun Solaris, and ANSI C
Under the ANSI C standard, the programmer who implements the library chooses how certain
functions behave. As a result, two implementations of a function can behave differently and
still conform to the ANSI standard. Because LabWindows/CVI now uses the Sun Solaris C
library, incompatibilities arise from the following sources:
•
•
Differences between LabWindows/CVI and the ANSI standard
Differences between LabWindows/CVI and the Sun Solaris standard
This section outlines these incompatibilities.
Note
None of these incompatibilities interfere with development of projects and
standalone executables in LabWindows/CVI for Sun.
Between LabWindows/CVI and ANSI C
The following incompatibilities exist between LabWindows/CVI and ANSI C:
•
LabWindows/CVI for Solaris 1 defines size_tas a signed integer instead of an
unsigned integer as the ANSI C standard requires. National Instruments uses the
signed integer definition to make LabWindows/CVI compatible with the Sun Solaris
header files.
•
•
LabWindows/CVI for Solaris 1 uses the Sun Solaris version of the ANSI function
strftime, which incorrectly interprets the "%W" control string as the one-based week
number instead of the zero-based week number as ANSI specifies.
In LabWindows/CVI for Solaris 1, ungetcworks improperly in certain cases:
-fsetposfails to erase all memory of pushback characters by ungetc.
-ungetcdoes not clear the end-of-file indicator on success.
-ungetcfails in certain cases after reading to the end of a file.
•
•
In LabWindows/CVI for Solaris 1, signal handlers you install with the signalfunction
remain installed after invocation of the handler. The ANSI standard specifies that these
handlers be removed before they are invoked.
In standalone executables LabWindows/CVI creates for Solaris 1, the function abort
and the macro assertdo not terminate the program if you install a signal handler for the
SIGABRTsignal and the handler returns rather than calling longjmp. The ANSI standard
specifies that the program terminate in these cases.
•
Under some versions of Sun Solaris 2 (for example, Solaris 2.5), the ANSI function
setlocaledoes not work properly when running programs in the LabWindows/CVI
development environment. LabWindows/CVI links programs in the development
environment to the Sun Solaris static library libc.a, which contains a limited version
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of setlocale. In contrast, LabWindows/CVI links standalone executables to the shared
library libc.so, which contains the fully functional version of setlocale.
Between LabWindows/CVI and Sun Solaris
The following incompatibilities exist between LabWindows/CVI and Sun Solaris:
•
LabWindows/CVI does not support the long longdata type some header files on
Solaris 2 use. In LabWindows/CVI, you cannot use that data type or call functions that
use that data type.
•
LabWindows/CVI implements the data type long doubleas an 8-byte object, in the
same way that it implements double. Sun Solaris implements long doubleas a
16-byte object. As a result, Sun Solaris functions that use long doubledo not work
properly in LabWindows/CVI.
•
•
•
The LabWindows/CVI implementation of the printfand scanffamily of functions
does not support the Sun Solaris implementation of long double.
LabWindows/CVI does not support wide character constants (wchar_t) of the form
L'ab'.
The data types jmp_bufand sigjmp_bufthat the header file setjmp.hdefines are
different for LabWindows/CVI and Sun Solaris. The LabWindows/CVI versions of these
buffers are larger than the Sun Solaris versions because LabWindows/CVI stores
additional debugging information in them. As a result, you must be careful when you use
jmp_bufand sigjmp_bufobjects among multiple files. In particular, if you compile a
file in LabWindows/CVI with debugging enabled and the file uses setjmpor longjmp,
then your program must include the LabWindows/CVI version of setjmp.hto handle
those functions correctly. The same is true for sigjmp_buf, sigsetjmp, and
siglongjmp.
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6
Building Multiplatform
Applications
This chapter contains guidelines and caveats for writing platform-independent
LabWindows/CVI applications. LabWindows/CVI currently runs under Windows 3.1
and Windows 95/NT for the PC, and Solaris 1 and Solaris 2 for the SPARCstation.
One major feature of LabWindows/CVI is that it supports multiplatform programming.
Following a few simple guidelines assures the portability of a LabWindows/CVI application:
•
•
•
•
Write code in strict ANSI C.
Observe and repair all LabWindows/CVI compile, link, and run-time diagnostics.
Avoid using system dependent calls when possible.
Avoid using non-portable image formats and fonts in your user interface.
Multiplatform Programming Guidelines
LabWindows/CVI is portable because it uses ANSI C program files, LabWindows/CVI User
You must segregate any platform dependent code in your source code using conditional
preprocessor directives. You can use the built-in macros, such as _NI_mswin32_,
_NI_mswin16_, _NI_mswin_, _NI_unix_and _NI_sparc_. More information on the
macros that LabWindows/CVI automatically defines is available in the Compiler Defines
section of Chapter 1, LabWindows/CVI Compiler.
Library Issues
Avoid using Windows 32-bit SDK functions unless you intend your LabWindows/CVI
application to run only under Windows 95/NT.
The sopenand fdopenfunctions are available only under Windows. Avoid using them
unless you intend your LabWindows/CVI application to run only under Windows.
Avoid using UNIX host system library calls such as ioctl, fcntl, and so on, unless you
intend the LabWindows/CVI application to run only under UNIX. Refer to the Using the
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Chapter 6
Building Multiplatform Applications
Low-Level I/O Functions section in Chapter 1, LabWindows/CVI Compiler, of this manual,
for more information on how to use system library calls.
Under UNIX, the low-level I/O functions open, close, read, write, lseek, and eofare
available in the UNIX C library. Refer to the Using the Low-Level I/O Functions section
Chapter 1, LabWindows/CVI Compiler, of this manual, for more information on how to use
UNIX C low-level functions. These functions are portable to Windows if you include
lowlvlio.hin your Windows application.
In general, the ANSI C, User Interface, Analysis, Formatting and I/O, Utility, GPIB, VXI,
RS-232, and TCP libraries are portable across platforms. However, a few functions are not
multi-platform. The majority of these functions are in the Utility Library. The documentation
and function panels for the non-portable functions contain notes that list the platforms to
which they apply.
Only LabWindows/CVI for Windows has DDE, Data Acquisition, and Easy I/O for DAQ
libraries. The X Property Library is available only under UNIX. The ActiveX Automation
Library is available only under Windows 95/NT.
Although LabWindows/CVI provides the TCP Library on all platforms, you are responsible
for ensuring that the system has hardware and software support for the TCP server.
Various processor architectures store integers and floating point numbers in different byte
order. To circumvent these inconsistencies, use the [o]modifier in the Formatting and I/O
Library to describe the byte ordering of device data. In a Fmt/Scanfunction, use the [o]
modifier to describe the byte ordering for the buffer that contains the raw device data. Do not
use the [o]modifier on the buffer that holds the data in the byte ordering of the host
processor. For example, if you use a GPIB instrument that sends two-byte binary data in Intel
byte order, use the following code:
short instr_buf[100];
short prog_buf[100];
status = ibrd (ud, instr_buf, 200);
Scan (instr_buf, "%100d[b2o01]>%100d[b2]", prog_buf);
If you use a GPIB instrument that sends two-byte binary data in Motorola byte order, use
Scanas shown in the following example:
Scan (instr_buf, "%100d[b2o10]>%100d[b2]", prog_buf);
In either case, use the [o]modifier only on the buffer that contains the raw data from the
instrument (instr_buf). LabWindows/CVI ensures that the program buffer (prog_buf)
uses the proper byte order for the host processor. For a full description of the [o]modifier,
refer to Chapter 2, Formatting and I/O Library, of the LabWindows/CVI Standard Libraries
Reference Manual.
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Chapter 6
Building Multiplatform Applications
Externally Compiled Modules
Although you can use externally compiled modules in LabWindows/CVI as this manual
describes, the best medium for application portability is ANSI C source code. Object modules
are not directly portable from one platform to another because the object file formats on the
various platforms differ.
For example, the object file formats are different among Windows 3.1, Windows 95/NT, and
UNIX systems. Although SPARCstations have the same computer architecture, Solaris 1.x
(Sun OS 4.x) and Solaris 2.x also use different object file formats that make object modules
non-portable even between these two systems.
To use an externally compiled module across platforms, you must recompile the source code
for the module with a compiler for the target system.
Multiplatform User Interface Guidelines
Function panel (.fp) files are portable across platforms.
User Interface Resource (.uir) files are portable across platforms.
Image file formats other than PCX (.pcx) are not portable.
Color hue and intensity differences between platforms are unavoidable.
The only fonts sure to be available on all platforms are the National Instruments fonts.
National Instruments fonts of the same name resemble each other stylistically from one
platform to another, although some relative size differences might exist. The National
Instruments Meta Fonts are of uniform size (height) relative to the rest of the user interface
and are the most portable family of fonts available. However, the width of the National
Instruments Meta Fonts might differ slightly from one platform to another. Allow for extra
space in the width of all control labels to assure consistent appearance.
You might find the User Interface library functions GetCtrlBoundingRect,
GetTextDisplaySize, and GetScreenSizeuseful in calculating and compensating for
font-size discrepancies between platforms.
The order in which LabWindows/CVI processes user interface events might differ between
Windows and UNIX platforms. This happens because of differences between the underlying
window management systems that LabWindows/CVI uses.
You must not assign the forward <Delete> key as a hot-key in your user interface, because
that key does not exist on all platforms.
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7
Creating and
Distributing Standalone
Executables and DLLs
This chapter describes how the LabWindows/CVI Run-time Engine, DLLs, externally
compiled modules, and other files interact with your executable file. This chapter also
describes how to perform error checking in a standalone executable program. You can
create executable programs from any project that runs in the LabWindows/CVI environment.
Introduction to the Run-Time Engine
With your purchase of LabWindows/CVI, you received the Run-time Engine as part of your
distribution. The LabWindows/CVI Run-time Engine is necessary to run executables or use
DLLs you create with LabWindows/CVI, and it must be present on any target computer on
which you want to run your executable program. You can distribute the Run-time Engine
according to your license agreement.
Distributing Standalone Executables under Windows
Under Windows, you can bundle the LabWindows/CVI Run-time Engine with your
distribution kit using the Create Distribution Kit command in the Build menu of the
Project window, or you can distribute it separately by making copies of the Run-time Engine.
Minimum System Requirements for Windows 95/NT
To use a standalone executable or DLL that depends on the LabWindows/CVI Run-time
Engine, you must have the following:
•
•
•
•
•
Windows 95, or Windows NT version 4.0 or later
A personal computer with at least a 33 MHz 486 or higher microprocessor
A VGA resolution or higher video adapter
A minimum of 8 MB of memory
Free hard disk space equal to 4 MB, plus space to accommodate your executable or DLL
and any files the executable or DLL requires
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Creating and Distributing Standalone Executables and DLLs
No Math Coprocessor Required for Windows 95/NT
You do not have to have a math coprocessor or emulator to use the LabWindows/CVI
Run-time Engine under Windows 95/NT.
Minimum System Requirements for Windows 3.1
To run a standalone executable you create using LabWindows/CVI for Windows, you must
have the following:
•
•
•
MS-DOS, version 3.1 or later
Microsoft Windows operating system, version 3.1 or later
A personal computer with at least a 25 MHz 386 or higher microprocessor. National
Instruments recommends a 33 MHz 486 or higher microprocessor.
•
•
•
•
A VGA resolution or higher video adapter
A math coprocessor
A minimum of 4 MB of memory
Free hard disk space equal to 2 MB, plus space to accommodate your executable and any
files the executable requires
Math Coprocessor Software Emulation for Windows 3.1
To run a standalone executable you create using LabWindows/CVI for Windows 3.1, your
system must have a math coprocessor. LabWindows/CVI recognizes the following
coprocessor emulation programs.
• wemu387.386from Watcom
•
Q387 from Quickware
Distributing Standalone Executables under UNIX
The Create Distribution Kit command is not available with UNIX versions of
LabWindows/CVI. However, you can use one of several UNIX shell scripts in themisc/bin
directory of the LabWindows/CVI installation directory to package your standalone programs
for distribution.
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Distributing Standalone Executables under Solaris 2
under Solaris 2, complete the following steps.
1. If your program loads .uirfiles with LoadPanelor loads external modules with
LoadExternalModule, use caution when you specify the filenames in calls to these
functions. If you use a relative path, the path is relative to the directory that contains
the executable. Refer to the Location of Files on the Target Machine for Running
Executables and DLLs section later in this chapter for more information.
2. Create a directory to contain your executable program and associated files. Structure the
directory exactly as you want it to appear after installation. Test your program by running
it from that directory.
3. From the directory that contains your executable program and associated files, execute
the makepkgshell script in the misc/bindirectory of the LabWindows/CVI installation
directory to create a distribution package. The script requires the following information
to build the package:
•
Abbreviated package name that can have up to nine characters in the form
XYZmyapp
•
•
•
Text name for the package
Default installation base directory on the user’s machine
Directory to place the build package
The script requests the following information, which is optional:
•
•
•
Company or vendor name for the package
Name and path to a copyright notice file for the package
Relative path and executable name to create as a symbolic link
4. The makepkgscript creates the following files and directory structure. In the following
paths, pkgnamestands for the name of your application package.
pkgname/install/copyright
pkgname/install/postinstall
pkgname/install/preremove
pkgname/pkginfo
pkgname/pkgmap
pkgname/reloc/pkgname/contents of application directory
You can now place the pkgnamedirectory and its contents onto your distribution media.
5. To run your executable, you must have the LabWindows/CVI Run-time Engine. You can
build the package for the LabWindows/CVI Run-time Engine by executingmakecvirte
located in the misc/bindirectory of the LabWindows/CVI installation directory. The
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makecvirtescript prompts you to name the directory in which to place the completed
package. The package name is NICcvirte.
6. To install or remove a package on a machine you must log in as root. You can then use
either of the following two methods to install or remove a package:
•
Use the Software Management Tool swntoollocated in the /usr/sbindirectory
of your system.
•
Use the following command to install a package:
pkgadd -d <path to package> pkgname
To remove a previously installed package, issue the following command:
pkgrm pkgname
Distributing Standalone Executables under Solaris 1
To distribute executable programs under Solaris 1, complete the following steps.
1. If your program loads UIR files with LoadPanelor loads external modules with
LoadExternalModule, use caution when you specify filenames in calls to these
functions. If you use a relative path, the path is relative to the directory that contains the
executable. Refer to the Location of Files on the Target Machine for Running
Executables and DLLs section in this chapter for more information.
2. Create a directory containing your executable program and associated files. Structure the
directory exactly as you want it to appear after installation. To test your program, run it
from that directory.
3. Use the shell script makedistin the misc/bindirectory to create a distribution
package. This script creates a compressed tar file that contains the directory you created
in Step 2 and a copy of the LabWindows/CVI Run-time Engine.
4. Make a copy of the installation script INSTALL.samplein the misc/bindirectory and
customize it using the information makedistprovides. This installation script unpacks
a distribution package, creating a directory like the one you created in Step 2, and then
installs the LabWindows/CVI Run-time Engine. The installation script can install from
floppy disks or from the current directory.
5. If you want to distribute your program on floppy disks, use the shell script makefloppy
in the misc/bindirectory to copy your installation script and distribution package to
floppy disks. If you want to distribute using some other method, such as anonymous FTP,
you must provide users with the package file that makedistcreates and the customized
installation script that extracts the files from the package.
You can use this method under Solaris 2 if you do not want to use the pkgmkutility.
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Minimum System Requirements for UNIX
To run a standalone executable you create using LabWindows/CVI for UNIX, your system
must have the following:
•
•
•
•
•
Sun SPARCstation
Solaris 1.x (SunOS 4.1.2 or higher) or Solaris 2.4 or higher
At least 24 MB of RAM
At least 32 MB of disk swap space
Free hard disk space equal to 4 MB, plus space to accommodate your executable and any
files the executable requires
Translating the Message File
The message file, called msgrtn.txtwhere nis the version number of the Run-time Engine,
is a text file that contains the error messages that the Run-time Engine displays. It resides in
the bindirectory of the Run-time Engine installation directory. You can translate the message
file into other languages. To translate the message file, perform the following steps.
1. Copy the file to another name so you have it as a backup.
2. Use a text editor to modify msgrtn.txt. Translate only the text that is inside quotation
marks. You must not add or delete any message numbers.
3. Execute the countmsg.exeor countmsgutility on the file to encode it for use with the
Run-time Engine, as in the following example:
countmsg msgrt5.txt
Configuring the Run-Time Engine
This section applies to you, the developer, and the user of your executable program. Feel free
to use the text in this section in the documentation for your executable program.
Solaris 1 Patches Required for Running Standalone Executable
Executables you create using LabWindows/CVI do not run properly on some versions of
Solaris 1 (SunOS 4) unless you patch the dynamic linker (/usr/lib/ld.so). For this
reason, you might have to patch the operating system on the machine on which you install
your standalone executable.
The required patches are available from Sun and also come with LabWindows/CVI. You can
either install the patch automatically using the installation script in the directory that contains
the patch, or you may install the patch manually by following the instructions that come with
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the patch. The required patches are available in the misc/patchsubdirectory of the
LabWindows/CVI installation directory. The following patches are available:
•
•
•
Patch-ID #100257-06 for SunOS 4.1.3/4.1.3c
Patch-ID #101743-02 for SunOS 4.1.3_U1
Patch-ID #101783-02 for SunOS 4.1.1/4.1.2
Configuration Option Descriptions
The Run-time Engine recognizes various configuration options. Under Windows platforms,
the installation program for the Run-time Engine automatically sets the required
configuration options for you.
Refer to the How to Set the Configuration Options discussion in Chapter 1, Configuring
LabWindows/CVI, of the LabWindows/CVI User Manual for detailed instructions on how to
manually set configuration options on each platform for the LabWindows/CVI development
environment. Under UNIX, you set the Run-time Engine configuration options in the same
manner. Under Windows, you set the Run-time Engine configuration options in a similar
manner, but with the following differences:
•
Under Windows 95/NT, set the configuration options in the Registry under the
following key:
HKEY_LOCAL_MACHINE\Software\National Instruments
\CVI Run-Time Engine\cvirte
•
Under Windows 3.1, set the configuration options in the [cvirtn] section of the
win.inifile, where nis the version of the Run-time Engine.
Note
Under UNIX, changes to options do not take effect until you restart your X server
or issue the xrdb.Xdefaultscommand.
cvirtx (Windows 3.1 Only)
Because executables load and execute the Run-time Engine under Windows 3.1, they must be
able to locate the Run-time Engine on the hard disk. Under Windows 3.1, executables find the
Run-time Engine using cvirtn, where nis the version number of the Run-time Engine,
configuration option.
Assign the pathname of the Run-time Engine executable file to the cvirtnoption in the
[cvirtn]section of win.ini, as in the following example:
[cvirt5]
cvrt5=c:\windows\system\cvirt5\cvirt5.exe
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cvidir (Windows Only)
Under Windows 95/NT, cvidirspecifies the location of the directory that contains the bin
and fontssubdirectories that the Run-time Engine requires. This Registry entry is necessary
to enable the Windows 95/NT Run-time Engine DLL to load. When you install the
LabWindows/CVI Run-time Engine under Windows 95/NT, the installation program places
the binand fontssubdirectories in the cvirtedirectory under the Windows system
directory. The installation program also creates the cvidirentry in the Registry.
For Windows 3.1, set the cvidiroption only if the Run-time Engine resides in a directory
other than the directory that contains the binand fontssubdirectories. Set it to the directory
that contains the binand fontssubdirectories.
useDefaultTimer (Windows Only)
The LabWindows/CVI Run-time Engine recognizes the UseDefaultTimeroption under
Windows platforms. It has the same effect as in the LabWindows/CVI development
environment. Refer to Chapter 1, Configuring LabWindows/CVI, in the LabWindows/CVI
User Manual, for more information on useDefaultTimer.
DSTRules
The LabWindows/CVI Run-time Engine recognizes the DSTRulesoption. It has the same
effect as in the LabWindows/CVI development environment. Refer to Chapter 1, Configuring
LabWindows/CVI, in the LabWindows/CVI User Manual, for more information
on DSTRules.
UNIX Options
The LabWindows/CVI Run-time Engine recognizes the activate, appFont, dialogFont,
editorFont, menuFont, messageBoxFont, useDefaultColors, useMetaKey, and
warpMouseOverDialogBoxesoptions under UNIX platforms. They have the same effect
as in the LabWindows/CVI development environment. Refer to Chapter 1, Configuring
LabWindows/CVI, in the LabWindows/CVI User Manual, for more information on these
options.
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In order for your executable to run successfully on a target computer, all files the executable
requires must be accessible. Your final distribution kit must contain all the necessary files to
install your LabWindows/CVI executable program on a target machine as shown in
Figure 7-1.
Executable
LW/CVI Run-Time Engine
startup code
program
execution
support
compiled
source code
memory
instrument
driver code
management
built-in
.obj's or .o's
.lib's or .a's
CVI Libraries
application
name & icon
resource
UIR,
image,
& state
files
DLLs
&
PTHs
external
.lib's or
.a's
external
.obj's or
.o's
other
files
Figure 7-1. Files Necessary to Run a LabWindows/CVI Executable Program on a Target Machine
•
•
Executable—This file contains a precompiled, prelinked version of your
LabWindows/CVI project and any instrument driver program files that you link to your
project. It also contains the application name and icon resource to register to the
operating system. The executable has an associated icon on which you can double-click
to start the application. When the executable starts, it loads the Run-time Engine. Under
UNIX, the executable returns the value that mainreturned or the value you passed
to exit.
Run-time Engine—The Run-time Engine contains all the built-in library, memory, and
program execution code present in the LabWindows/CVI environment, without all the
program development tools such as the source editor, compiler, debugger, and user
interface editor. The Run-time Engine is smaller than the LabWindows/CVI environment
and thus loads faster and requires less memory. You use only one copy of the Run-time
Engine on each target machine even when you have multiple executables. Under
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Windows 95/NT, the Run-time Engine consists of multiple files, including three DLLs
and the low-level support driver. Under Windows 3.1, the Run-time Engine is an
execute-only version of the LabWindows/CVI environment. Under Sun Solaris, the
Run-time Engine is a shared library
•
•
•
•
•
UIR files—The User Interface Resource files that your application program uses. Use
LoadPaneland LoadMenuBarto load these files.
Image files—The graphical image files that you programmatically load and display on
your user interface using DisplayImageFile.
State files—The user interface panel state files that you save using SavePanelState
and load using RecallPanelState.
DLL files—(Windows Only) the Windows Dynamic Link Library files that your
application program uses.
PTH files—(Windows 3.1 Only) specify the location of DLL files when you want to
load the DLL from a special directory, or indicate that you want to find a DLL using
the standard Windows DLL search algorithm.
•
•
•
External .lib or .a files—Compiled 32-bit .libfiles on the PC or .afiles under UNIX
that you load using LoadExternalModuleand that you have not listed in the project.
External .obj or .o files—Compiled 32-bit .objfiles on the PC or .ofiles under UNIX
that you load using LoadExternalModuleand that you have not listed in the project.
Other files—Files your executable opens using open, fopen, OpenFile, and so on.
Necessary Files for Using DLLs Created
in Windows 95/NT
Under Windows 95/NT, you can distribute DLLs that use the LabWindows/CVI Run-time
Engine. As in the case of standalone executables, you must distribute them along with the
LabWindows/CVI Run-time Engine.
Location of Files on the Target Machine for Running
Executables and DLLs
To assure proper execution, it is critical that all files associated with your executable program
are in the proper directories on the target machine. On the PC, you specify these files in a
relative directory structure in the dialog box that appears when you select Create
Distribution Kit from the Build menu of the Project window in LabWindows/CVI. Refer to
the LabWindows/CVI User Manual for details. This section describes the proper location of
each of the files shown in Figure 7-1.
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LabWindows/CVI Run-Time Engine under Windows 95/NT
Table 7-1 shows the files that comprise the LabWindows/CVI Run-time Engine for
Windows 95/NT.
Table 7-1. LabWindows/CVI Run-Time Engine Files
Run-Time Engine File
cvirt.dll
Description
Helper DLL
cvirte.dll
Contains most LabWindows/CVI libraries
Contains ActiveX Automation Library
cviauto.dll
cvi95vxd.vxd
cvintdrv.sys
msgrtn.txt
Low-level support driver for Windows 95
Low-level support driver for Windows NT
Contains text messages; nis Run-time Engine version number
cvirtn.rsc
Contains binary resources; nis Run-time Engine version
number
ni7seg.ttf
Font description file
Font description file
nisystem.ttf
These files come on a separate diskette, or in a separate directory in the CD-ROM. The
LabWindows/CVI installation program installs the files along with the development
environment. The Create Distribution Kit command in the Build menu of the Project
window can bundle the Run-time Engine DLLs and drivers into your distribution kit. Also,
you can make copies of this diskette, or the CD-ROM directory, for separate distribution.
Run-Time Library DLLs
The installation program always places the Run-time Engine DLLs in the Windows system
directory under Windows 95 and the Windows system32directory under Windows NT.
Low-Level Support Driver
The Run-time Engine loads the low-level support driver if it is present when you start your
standalone executable. Several functions in the Utility Library require the low-level
support driver. Refer to the function reference for CVILowLevelSupportDriverLoadedin
Chapter 8, Utility Library, of the LabWindows/CVI Standard Libraries Reference Manual for
more information on these functions.
The installation program installs the low-level support driver in the Windows system
directory under Windows 95 and the Windows system32\driversdirectory under
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Windows NT. Under Windows NT, the installation program also adds a registry entry under
the following key:
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\cvintdrv
Table 7-2 shows the values the installation program sets for the Windows NT registry entry
for the low-level support driver.
Table 7-2. Windows NT Registry Entry Values for the Low-Level Support Driver
Type
Name
ErrorControl
Group
Value
00000001
DWORD
String
"Extended Base"
00000002
Start
DWORD
DWORD
Type
00000001
Message, Resource, and Font Files
The installation program installs ni7seg.ttf and nisystem.ttfin the cvirte\fonts
subdirectory under the directory in which it installs the Run-time Engine DLLs. It installs the
msgrtn.txtand cvirtn.rscin the cvirte\binsubdirectory under the directory in
which it installs the Run-time Engine DLLs. It sets the cvidiroption in the following
registry key to the pathname of the cvirtedirectory.
HKEY_LOCAL_MACHINE\Software\National Instruments
\CVI Run-Time Engine\cvirte
You can subsequently change the location of the binand fontssubdirectories, but you must
also change the cvidirregistry option to the pathname of the directory that contains the two
subdirectories.
National Instruments Hardware I/O Libraries
The LabWindows/CVI Run-time Engine does not include the DLLs or drivers for National
Instruments hardware. Users can install the DLLs and drivers for their hardware from the
distribution disks that National Instruments supplies.
LabWindows/CVI Run-Time Engine under Windows 3.1
For Windows 3.1, the LabWindows/CVI Run-time Engine comes in the form of an executable
file. The name of the executable file is cvirtn.exe, where nis the version of the Run-time
Engine. The Run-time Engine comes on a separate diskette. The LabWindows/CVI
installation program installs the Run-time Engine along with the development environment.
The Create Distribution Kit command in the Build menu of the Project window can bundle
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the Run-time Engine into your distribution kit. Also, you can make copies of this diskette for
separate distribution. The user selects the directory into which to install the Run-time Engine.
The LabWindows/CVI Run-time Engine does not include the DLLs or drivers for National
Instruments hardware. Users can install the DLLs or drivers for their hardware from the
distribution disks that National Instruments supplies.
LabWindows/CVI Run-Time Engine under Sun Solaris
Under Sun Solaris, the Run-time Engine comes in the form of a shared library called
libcvi.so.n, where nis the version number of the Run-time Engine. The installation
program installs the shared library in the libsubdirectory under the Run-time Engine
installation directory. It also creates two symbolic links, where cvirtestands for the
Run-time Engine installation directory, as shown in Table 7-3.
Table 7-3. Pathnames and Targets of Links
Pathname of Link
/usr/lib/libcvi.so
/usr/lib/libcvi.so.n
Target of Link
/usr/lib/libcvi.so.n
cvirte/lib/libcvi.so.n
The installation program installs message and resource files in the bindirectory under the
Run-time Engine installation directory. It installs font description files in the fontsdirectory
under the Run-time Engine installation directory. You can subsequently change the location
of the binand fontssubdirectories, but you must also change the cvidirconfiguration
option to the pathname of the directory that contains the two subdirectories.
The LabWindows/CVI Run-time Engine does not include the shared libraries or drivers for
National Instruments hardware. Users can install the shared libraries and drivers for their
hardware from the distribution disks that National Instruments supplies.
Rules for Accessing UIR, Image, and Panel State Files on All Platforms
The recommended method for accessing UIR, image, and panel state files in your executable
program is to place the files in the same directory as the executable and pass simple filenames
with no drive letters or directory names to LoadPanel, DisplayImageFile,
SavePanelState, and RecallPanelState.
If you do not want to store these files in the same directory as your executable,
you must pass pathnames to LoadPanel, DisplayImageFile, SavePanelState, and
RecallPanelState. These functions interpret relative pathnames as being relative to the
directory that contains the executable.
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Rules for Using DLL Files under Windows 95/NT
Under Windows 95/NT, your executable or DLL can link to a DLL only through an
import library. This section refers to a DLL an executable or another DLL uses as a subsidiary
DLL. You can link an import library into your program in any of the following ways:
•
•
•
List it in your project.
Associate it with the .fpfile for an instrument driver or user library.
If you list a DLL import library in the project or associate it with an instrument driver or user
library, LabWindows/CVI statically links the import library into your executable or DLL. On
the other hand, if you load the import library through a call to LoadExternalModule, you
must distribute it separately from your executable. Refer to the Rules for Loading Files Using
LoadExternalModule section later in this chapter for more information.
Regardless of the method you use to link the import library, you must distribute the subsidiary
DLL separately. The import library always contains the name of the subsidiary DLL. When
your executable or DLL is loaded, the operating system finds the subsidiary DLL using the
standard DLL search algorithm, which the Windows SDK documentation for the
LoadLibraryfunction describes. The search precedence is as follows:
1. The directory from which the user loads the application
2. The current working directory
3. Under Windows 95, the Windows systemdirectory. Under Windows NT, the Windows
system32and systemdirectories
4. The Windows directory
5. The directories listed in the PATHenvironment variable
The Create Distribution Kit command automatically includes in your distribution kit the
DLLs that the import libraries in your project refer to. You must add to the distribution kit
any DLLs that you load through LoadExternalModuleor that you load by calling the
Windows SDK LoadLibraryfunction.
Do not include DLLs for National Instruments hardware in your distribution kit. The user
must install these DLLs from the distribution disks that National Instruments supplies.
Rules for Using DLL Files under Windows 3.1
LabWindows/CVI never links DLL files and DLL path files into the executable, so you must
distribute them as separate files. The Create Distribution Kit command automatically
includes DLLs that your project refers to in your distribution kit. The only exceptions are
DLLs for National Instruments hardware and DLLs that you load using
LoadExternalModule.
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Do not include DLLs for National Instruments hardware in your distribution kit. The user
must install these DLLs from the distribution disks that National Instruments supplies.
If you use LoadExternalModuleto load DLLs, refer to the following section, Rules for
Loading Files Using LoadExternalModule.
If you use a DLL file, a DLL path file, or a DLL glue object module in your project or as an
instrument driver, the Run-time Engine always looks for a corresponding DLL path (.pth)
file before it looks for the DLL itself. This search mechanism lets the user of your executable
place the DLLs anywhere on the target computer. The Run-time Engine uses the following
DLL search method.
1. Look for a .pthfile in the directory of the executable. The .pthfile must have the same
base name as the file in the project or as the instrument driver. If the .pthfile contains
an absolute path to the DLL, use that path to find the DLL. If the .pthfile contains a
simple filename, use the standard Windows DLL search algorithm: directory of
executables, current working directory, \windows, \windows\system, then the PATH
environment variable.
2. Look for a .dllfile in the directory of the executable. The .dllfile must have the same
base name as the file in the project or as the instrument driver.
3. Otherwise, use the standard Windows DLL search algorithm.
Note
Before searching for a .dllfile, the Run-time Engine always looks for a
.pthfile. Therefore, your choice of whether to use a .pthfile when you develop
your application in the LabWindows/CVI environment does not restrict your
choice of whether to use a .pthfile in the standalone application.
Rules for Loading Files Using LoadExternalModule
LoadExternalModulecan load the following file types:
Library Files:
.lib(Windows) or .a(UNIX)
.obj(Windows) or .o(UNIX)
.lib(Windows 95/NT only)
.pth(Windows 3.1 only)
Object Modules:
DLL Import Library Files:
DLL Path Files:
DLL Files:
.dll(Windows 3.1 only)
Source Files:
.c(linked into your executable or DLL)
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Forcing Modules that External Modules Refer to
into Your Executable or DLL
In the LabWindows/CVI development environment, external modules can link to modules in
the Instrument and Library menus regardless of whether you refer to them elsewhere in
your project. However, when you create a standalone executable, LabWindows/CVI includes
in the executable only modules that your project refers to directly. If an external module refers
to modules not included in the executable, calls to RunExternalModuleor
GetExternalModuleAddron that external module fail.
To avoid this problem, you must force any missing modules into your executable or DLL.
You can do this when you create your executable or DLL by using the Add Files To
Executable or Add Files To DLL button to display a list of project .lib, project .a,
Instrument, and Library files. Select the files you want to include in your executable or DLL.
If you select a .libor .afile, it is linked in its entirety.
Alternatively, you can link modules into your executable or DLL by including dummy
references to them in your program. For instance, if your external module references the
functions FuncXand FuncY, include the following statement in your program:
void *dummyRefs[] = {(void *)FuncX, (void *)FuncY};
Using LoadExternalModule on Files in the Project
You can call LoadExternalModuleon files listed in the project. You must pass the simple
•
If you link your executable or DLL in LabWindows/CVI, the following rules apply for
files listed in the project:
–
–
For .cor .objfiles, everything works automatically.
For .dllor .pthfiles (Windows 3.1 only), refer to the Rules for Using DLL Files
under Windows 3.1 section earlier in this chapter.
–
For .libfiles, by default, Create Standalone Executable File or Create Dynamic
Link Library only links in the library modules that you reference statically in the
project. Therefore, you must force into the executable the modules that contain the
functions you call using GetExternalModuleAddr.
To force these modules into the executable, include the library file in the project and
take one of the following actions:
•
If you want to force the entire library file into the executable, use the Add Files
to Executable button in the Create Standalone Executable File dialog box, or
the Add Files to DLL button in the Create Dynamic Link Library dialog box.
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•
If you want to force only specific modules from the library into the executable,
reference them statically in your program. For example, you could have an array
of void pointers and initialize them to the names of the necessary symbols.
•
If you link in an external compiler under Windows 95/NT, the LabWindows/CVI Utility
library does not know the location of symbols in the externally linked executable or DLL.
Consequently, without further action on your part, you cannot call
GetExternalModuleAddror RunExternalModuleon modules that you link directly
into your executable or DLL. Your alternatives are as follows.
1. Remove the file from the project and distribute it as a separate .obj, .lib,
or .dll.
2. Use the Other Symbols section of the External Compiler Support dialog box in
the Build menu of the Project window to create an object module that contains
a table of symbols you want GetExternalModuleAddrto find. If you use this
method, pass the empty string ("") to LoadExternalModuleas the module
pathname. The empty string indicates that you linked the module directly into
your executable or DLL using an external compiler.
Using LoadExternalModule on Library and Object Files
Not in the Project
If you call LoadExternalModuleon a library or object file not in the project, you must keep
the library or object file separate in your distribution.
When you keep an object or library file separate, you can manage memory more efficiently
and replace it without having to replace the executable. For this reason, if you call
LoadExternalModuleon a library or object in the project, remove or exclude the file from
the project before you select Create Standalone Executable File or Create Dynamic Link
Library, and then include it as a separate file when you use Create Distribution Kit.
However, remember that you cannot statically reference functions defined in a separate
library or object file from the executable or DLL. You must use LoadExternalModuleand
GetExternalModuleAddrto make such references.
When you distribute the library or object file as a separate file, it is a good idea to place the
file in the same directory as the executable or DLL. If you place the file in the same directory,
you can pass a simple filename to LoadExternalModule. If you do not want the file to be
in the same directory as your executable, you must pass a pathname to
LoadExternalModule. LoadExternalModuleinterprets relative pathnames as being
relative to the directory that contains the executable or DLL.
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LoadExternalModule. Instead, you must pass the pathname of a DLL import library. You
can link the import library into your executable or DLL or distribute it separately and load it
dynamically. For import libraries that you link into your executable or DLL, refer to the Using
LoadExternalModule on Files in the Project section earlier in this chapter. For import
libraries that you load dynamically, refer to the Using LoadExternalModule on Library and
Object Files Not in the Project section earlier in this chapter.
You must always distribute DLLs as separate files. The operating system finds the DLL
associated with the loaded import library using the standard Windows DLL search algorithm.
The search precedence is as follows.
1. The directory from which the application loads
2. The current working directory
3. Under Windows 95, the Windows systemdirectory. Under Windows NT, the Windows
system32and systemdirectories
4. The Windows directory
5. The directories the PATHenvironment variable lists
Using LoadExternalModule on DLL and Path Files
under Windows 3.1
DLL files and DLL path files are never linked into the executable, so you must distribute them
as separate files.
Your executable can call LoadExternalModuledirectly on a DLL or DLL path file only if
you include the DLL or DLL path file in the project. When you select Create Standalone
Executable File, LabWindows/CVI automatically creates the DLL glue code and links it into
the executable.
Also, you can pass the DLL glue object module filename to LoadExternalModule. You can
generate the DLL glue object module by opening the .hfile for the DLL in a Source window
of LabWindows/CVI and selecting Generate DLL Glue Object from the Options menu.
If you include the DLL, the DLL path file, or the DLL glue object module as a file in the
project, you must pass LoadExternalModulea simple filename, and it uses the following
search method to find the DLL.
1. Look for a .pthfile in the directory of the executable. The .pthfile must have the same
base name as the file you passed to LoadExternalModule. If the .pthfile contains an
absolute path to the DLL, use that path to find the DLL. If the .pthfile contains a simple
filename, use the standard Windows DLL search algorithm: directory of executables,
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Chapter 7
Creating and Distributing Standalone Executables and DLLs
current working directory, \windows, \windows\system, then the PATHenvironment
variable.
2. Look for a .dllfile in the directory of the executable. The .dllfile must have the same
base name as the file you passed to LoadExternalModule.
3. Otherwise, use the standard Windows DLL search algorithm.
If you maintain the DLL glue object module as a separate file from the executable, you must
pass LoadExternalModulea pathname to the DLL glue object module, and it uses the
following search method to find the DLL.
1. Look for a .pthfile that is in the same directory as the DLL glue object module and that
has the same base name as the DLL glue object module. If the .pthfile contains an
absolute path to the DLL, use it to find the DLL. If the .pthfile contains a simple
filename, use the standard Windows DLL search algorithm.
2. Look for a .dllfile that is in the same directory as the DLL glue object module and that
has the same base name as the DLL glue object module.
3. Otherwise, use the standard Windows DLL search algorithm.
Note
Before searching for a .dllfile, a standalone executable always looks for a
.pthfile. Therefore, your choice of whether to use a .pthfile when you develop
your application in the LabWindows/CVI environment does not restrict your
choice of whether to use to .pth file in the standalone application.
Using LoadExternalModule on Source Files (.c)
If you pass the name of a source file to LoadExternalModule, the source file must be in the
project. LabWindows/CVI automatically compiles the source file and links it into the
executable when you select Create Standalone Executable File or Create Dynamic Link
Library. For this reason you must pass a simple filename to LoadExternalModule. If you
use an external compiler, refer to the, Using LoadExternalModule on Files in the Project,
section earlier in this chapter.
If the source file is an instrument driver program that is not in the project and you link in
LabWindows/CVI, you have two alternatives:
•
•
Add the instrument driver .c source to the project.
Refer to one of the variables or functions it exports in one of your project files.
If the source file is an instrument program that is not in the project and you link in an external
compiler, you must create an object file and keep it separate from the executable.
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Rules for Accessing Other Files
The functions for accessing files, such as fopen, OpenFile, SetFileAttrs, DeleteFile,
and so on, interpret relative pathnames as being relative to the current working directory.
Under Windows, the initial current working directory is normally the directory of the
executable. However, if a different directory exists in the Working Directory or Start In field
of the Properties dialog box for the executable, then it is the initial current working directory.
Under UNIX, the initial current working directory is the directory from which you invoke the
executable. You can create an absolute path for a file in the executable directory by using
GetProjectDirand MakePathname.
Error Checking in Your Standalone Executable or DLL
Usually, you enable debugging and the Break on Library Errors option while you develop
your application in LabWindows/CVI. With these features enabled, LabWindows/CVI checks
for programming errors in your source code. Consequently, you might have a tendency to
When you create a standalone executable program or DLL, all your source modules are
compiled. Compiled modules always disable debugging and the Break on Library Errors
option, resulting in smaller and faster code. Thus, you must perform your own error checking
when you create a standalone executable program or DLL. Refer to Chapter 9, Checking for
Errors in LabWindows/CVI, for details about performing error checking in your code.
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8
Distributing Libraries
and Function Panels
This chapter describes how to distribute libraries, add libraries to a user’s Library menu, and
specify library dependencies.
How to Distribute Libraries
You can distribute libraries for other users to include in their Library menu. You must create
a function panel (.fp) for each library program file. If you do not want to develop function
panels for the library functions, create a .fpfile without any classes or functions. In that case,
LabWindows/CVI loads the library at startup but does not include the library name in the
Library menu. This is useful when the library supports other libraries and contains no
user-callable functions.
Adding Libraries to User’s Library Menu
Normally, users must manually add libraries to the Library menu using the Library Options
command in the Project window Options menu. However, you can insert your libraries into
the user’s Library menu by modifying the user’s cvi.inifile under Windows 3.1,
.cvi.iniunder UNIX, or the Registry under Windows 95/NT.
Under Windows 3.1 and UNIX, the modiniprogram is in the LabWindows/CVI bin
subdirectory for this purpose. A documentation file called modini.docand the source code
are in the same directory.
Under Windows 95/NT, the modregprogram is in the LabWindows/CVI binsubdirectory
for this purpose. A documentation file called modreg.docand the source code are in the
same directory.
Assume that you install function panels for two libraries in the following location:
c:\newlib\lib1.fp
c:\newlib\lib2.fp
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Chapter 8
Distributing Libraries and Function Panels
To add the libraries to the user’s Library menu under Windows 3.1 and UNIX, your modini
command file must be:
add Libraries LibraryFPFile "c:\newlib\lib1.fp"
add Libraries LibraryFPFile "c:\newlib\lib2.fp"
After the user installs the library files, the modiniprogram must be run on the user’s disk
using cvi.iniand the command file.
To add the libraries to the user’s Library menu under Windows 95/NT, your modreg
command file must be:
setkey [HKEY_CURRENT_USER\Software\National Instruments]
appendkey CVI\@latestVersion
add Libraries LibraryFPFile "c:\newlib\lib1.fp"
add Libraries LibraryFPFile "c:\newlib\lib2.fp"
After the user installs the library files, the modregprogram must be run on the user’s disk
using the command file.
Caution
LabWindows/CVI must not be running when you use the modinior modreg
program to modify cvi.inior the Registry. If LabWindows/CVI is running while
you use these programs, you will lose your changes.
!
Specifying Library Dependencies
When one library you distribute is dependent upon another library you distribute, you can
specify this dependency in the function panel file for the dependent library. When
LabWindows/CVI loads the dependent library, it attempts to load the libraries upon which it
depends. Use the .FP Auto-Load List command in the Edit menu of the Function Tree Editor
window of the dependent library to list the .fpfiles of the libraries upon which it depends.
Refer to the Function Tree Editor chapter of the LabWindows/CVI Instrument Driver
Developers Guide for details on this command.
LabWindows/CVI can find the required libraries most easily when they are all in the same
directory as the dependent library. When you cannot put them in the same directory, you must
add the directories in which the required libraries reside to the user’s Instrument Directories
list. The user can manually enter this information using the Instrument Directories
command in the Project window Options menu. Also, you can add to the Instrument
Directories list by editing cvi.iniunder Windows 3.1, .cvi.iniunder UNIX, or the
Registry under Windows 95/NT.
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National Instruments recommends that your installation program modify cvi.ini,
.cvi.ini, or the Registry, automatically. Under Windows 3.1, the modiniprogram is in the
LabWindows/CVI binsubdirectory for this purpose. A documentation file called
modini.docand the source code are in the same directory.
Under Windows 95/NT, the modregprogram is in the LabWindows/CVI binsubdirectory
for this purpose. A documentation file called modreg.docand the source code are in the
same directory.
Assume that you install two .fpfiles in the following locations:
c:\newlib\liba.fp
c:\genlib\libb.fp
If libadepends on libb, you must add the following path to the user’s Instrument
Directories list:
c:\genlib
For LabWindows/CVI to be able to find the dependent file under Windows 3.1 and UNIX,
your modinicommand file must be,
add InstrumentDirectories InstrDir "c:\genlib"
After the user installs the library files, the modiniprogram must be run on the user’s disk
using cvi.iniand the command file.
For LabWindows/CVI to be able to find the dependent file under Windows 95/NT, your
modregcommand file must be,
setkey
[HKEY_CURRENT_USER\Software\National Instruments]
appendkey CVI\@latestVersion
add InstrumentDirectories InstrDir "c:\gewlib"
After the user installs the library files, the modregprogram must be run on the user’s disk
using the command file.
Caution
LabWindows/CVI must not be running when you use the modinior modreg
program to modify cvi.inior the Registry. If LabWindows/CVI is running while
you use these programs, you will lose your changes.
!
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9
Checking for Errors in
LabWindows/CVI
This chapter describes LabWindows/CVI error checking and how LabWindows/CVI reports
errors in LabWindows/CVI libraries and compiled external modules.
When you develop applications in LabWindows/CVI, you usually have debugging and the
Break on Library Errors option enabled. With these features enabled, LabWindows/CVI
identifies and reports programming errors in your source code. Therefore, you might have a
tendency to relax your own error checking. However, in compiled modules and standalone
executables, debugging and the Break on Library Errors are disabled. This results in smaller
and faster code, but you must perform your own error checking. This fact is important to
remember because many problems can occur in compiled modules and standalone
executables even if the program works inside the environment.
It is important to check for errors that can occur because of external factors beyond the control
of your program. Examples include running out of memory or trying to read from a file that
does not exist. malloc, fopen, and LoadPanelare examples of functions that can encounter
such errors. You must provide your own error checking for these types of functions. Other
functions return errors only if your program is incorrect. The following function call returns
an error only if pnlor ctrlis invalid.
SetCtrlAttribute(pnl, ctrl, ATTR_DIMMED, FALSE);
The Break on Library Errors feature of LabWindows/CVI adequately checks for these types
of errors while you develop your program, and external factors do not affect this function call.
Therefore, it is generally not necessary to perform explicit error checking on this type of
function call.
One method of error checking is to check the status of function calls upon their completion.
Most functions in commercial libraries return errors when they encounter problems.
LabWindows/CVI libraries are no exception. All the functions in the LabWindows/CVI
libraries and in the instrument drivers available from National Instruments return a status code
to indicate the success or failure of execution. These codes help you determine the problem
when the program does not run as you expected it to. This chapter describes how
LabWindows/CVI reports these status codes and some techniques for checking them.
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Chapter 9
Checking for Errors in LabWindows/CVI
Note
Status codes are integer values. These values are either common to an entire
library of functions, or specific to one function. Libraries that have a common set
of codes have a listing at the end of the chapter or manual they appear in. You can
find the error message for each integer value there. In addition, each of these
libraries contains a function you can call to translate the integer value to an error
string. When an error code is specific to a function, you can find a description for
it in the function description in the LabWindows/CVI manual set. The error
description also appears in the online help of the library function panels in
LabWindows/CVI.
Error Checking
LabWindows/CVI functions return status codes in one of two ways—either by a function
return value, or by updating a global variable. In some cases, LabWindows/CVI uses both of
these methods. In either case, it is a good idea to monitor these values so that you can detect
an error and take appropriate action. A common technique for error checking is to monitor the
status of functions, and when a function reports an error, pause the program and report the
error to the user through a pop-up message. For example, LoadPanelreturns a positive
integer when it successfully loads a user interface panel into memory. However, if a problem
occurs, the return value is negative. The following example shows an error message handler
for LoadPanel.
panelHandle = LoadPanel (0, "main.uir", PANEL);
if (panelHandle < 0) {
ErrorCheck ("Error Loading Main Panel", panelHandle,
GetUILErrorString (panelHandle));
}
When a function reports status through a separate function, as in the RS-232 Library, check
for errors in a similar way. In this case, the status function returns a negative value when the
original function fails.
bytesRead = ComRd (1, buffer, 10);
if (ReturnRS232Error() < 0) {
ErrorCheck ("Error Reading From ComPort #1", ReturnRS232Error(),
GetRS232ErrorString(ReturnRS232Error()));
}
Notice that the above function also returns the number of bytes read from the serial port. You
can compare the number of bytes read to the number you request, and if a discrepancy exists,
take the appropriate action. Notice that the error codes differ between the RS-232 Library and
the User Interface Library. A section describing how each LabWindows/CVI library reports
errors follows this section.
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After your program detects an error, it must take some action to either correct the situation or
prompt the user to select a course of action. The following example shows a simple error
response function.
void ErrorCheck (char *errMsg, int errVal, char *errString)
{
char outputMsg[256];
int response;
Fmt (outputMsg, "%s (Error = %d).\n%s\nContinue? ",
errMsg,errVal,errString);
response = ConfirmPopup ("ErrorCheck", outputMsg);
if (response == 0)
exit (-1);
}
Status Reporting by LabWindows/CVI Libraries
and Instrument Drivers
This section describes how LabWindows/CVI libraries and instrument drivers report errors.
Notice that libraries that return their status code using global variables or separate functions
sometimes report additional status information through return values.
User Interface Library
The User Interface Library routines return a negative value when they detect an error. Some
functions, such as LoadPanel, return positive values for a successful completion. This
library uses a common set of error codes, which the LabWindows/CVI User Interface
Reference Manual and the function panel help list. You can use the function
GetUILErrorStringto get the error message associated with each User Interface Library
error code.
Analysis/Advanced Analysis Libraries
The Analysis and Advanced Analysis Library functions return a negative value when they
detect an error. This library uses a common set of error codes, which the LabWindows/CVI
Standard Libraries Reference Manual, the LabWindows/CVI Advanced Analysis Reference
Manual, and the function panel help list. You can use the function
GetAnalysisErrorStringto get the error message associated with each Analysis Library
error code.
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Easy I/O for DAQ Library
The Easy I/O for DAQ Library functions return a negative value when they detect an error.
They return a positive value as a warning when they are able to complete their task but not in
the way you might expect. This library uses a common set of error codes. The positive
warning codes are the same absolute values as the negative error codes. Refer to the
LabWindows/CVI Standard Libraries Reference Manual or the function panel help for a
listing of the error codes and information on the individual functions. You can use
GetDAQErrorStringto get the error message associated with each Easy I/O for DAQ
Library error or warning code.
Data Acquisition Library
The Data Acquisition Library functions return a negative value when they detect an error.
They return a positive value as a warning when they are able to complete their task but not in
the way you might expect. This library uses a common set of error codes. The positive
warning codes are the same absolute values as the negative error codes.
Refer to the back of the NI-DAQ Function Reference Manual for PC Compatibles or the
function panel help for a listing of the error codes. You can use GetNIDAQErrorStringto
get the error message associated with each Data Acquisition Library error or warning code.
VXI Library
The VXI Library uses a variety of global variables and function return codes to report any
error that occurs. You must check each function description to determine what error checking
might be necessary. Refer to the specific VXI function reference manual or the on-line help
for a listing of the error codes.
GPIB/GPIB 488.2 Library
The GPIB libraries return status information through two global variables called ibsta
and iberr.
Note
If your program uses multiple threads, use the ThreadIbstaand ThreadIberr
functions in place of the ibstaand iberrglobal variables.
Note
The GPIB Library functions return the same value that they assign to ibsta. You
can choose to use either the return values, ibsta, or ThreadIbsta.
The ERRbit within ibstaindicates an error condition. If this bit is not set, iberrdoes not
contain meaningful information. If the ERRbit is set in ibsta, the error condition is stored in
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iberr. After each GPIB call, your program should check whether the ERRbit is set to
determine if an error has occurred, as shown in the following code segment.
if (ibwrt(bd[instrID], buf, cnt) & ERR)
PREFIX_err = 230;
Refer to your NI-488.2 Function Reference and user manuals for detailed information on
GPIB global variables and listings of status and error codes. LabWindows/CVI function panel
help also has listings of status and error codes.
RS-232 Library
The RS-232 library returns status information through a global variable called rs232err. If
this variable is negative after the function returns, an error occurred. Notice that many of the
functions return a value in addition to setting the global variable. Usually, this value contains
information on the result of the function that can also be used to detect a problem. Each
function should be checked individually. Refer to the RS-232 section in the LabWindows/CVI
Standard Libraries Reference Manual or the function panel help for a listing of the error codes
and information on the individual functions. You can use GetRS232ErrorStringto get the
error message associated with each RS-232 Library error code.
Note
If your program uses multiple threads, use the ReturnRS232Errfunction in
place of the rs232errglobal variable.
VISA Library
The VISA Library functions return a negative value when they detect an error. They return a
positive value as a warning when they can complete their task but not in the way you might
expect. This library uses a common set of error and warning codes, but the warning code
values are entirely separate from the error code values. The error codes always contain
0xBFFF in the upper two bytes. The warning codes always contain 0x3FFF in the upper two
bytes. Refer to the NI-VISA Programmer Reference Manual or the function panel help for a
listing of the error and warning codes and information on the individual functions. You can
use viStatusDescto obtain the error message associated with each VISA Library error
code.
IVI Library
The IVI Library functions return a negative value when they detect an error. This library uses
a common set of error codes. Refer to the LabWindows/CVI Instrument Driver Developers
Guide or the function panel help for a listing of the error codes and information on the
individual functions. IVI Library functions sometimes also provide a secondary error code or
an elaboration string to give you additional information about an error condition. You can use
Ivi_GetErrorInfoto obtain the primary error code, secondary error code, and the
elaboration string. You can use Ivi_GetErrorMessageto obtain the error message
associated with each IVI Library error code.
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TCP Library
The TCP Library functions return a negative value when they detect an error. This library uses
a common set of error codes, which the LabWindows/CVI Standard Libraries Reference
Manual and the LabWindows/CVI function panel help list. You can use
GetTCPErrorStringto get the error message associated with each TCP Library error code.
DDE Library
The DDE Library functions return a negative value when they detect an error. This library
uses a common set of error codes, which the LabWindows/CVI Standard Libraries Reference
Manual and the LabWindows/CVI function panel help list. You can use the function
GetDDEErrorStringto get the error message associated with each DDE Library error code.
ActiveX Automation Library
The ActiveX Automation Library functions return a negative value when they detect an error.
This library uses a common set of error codes. Refer to the LabWindows/CVI Standard
Libraries Reference Manual or the function panel help for a listing of the error codes and
information on the individual functions. You can use CA_GetAutomationErrorStringto
get the error message associated with each ActiveX Automation Library error code.
X Property Library
The X Property Library functions return a negative value when they detect an error. This
library uses a common set of error codes, which the LabWindows/CVI Standard Libraries
Reference Manual and the LabWindows/CVI function panel help list. You can use the
function GetXPropErrorStringto get the error message associated with each X Property
Library error code.
Formatting and I/O Library
This library contains the file I/O, string manipulation, and data formatting functions. All
functions return negative error codes when they detect an error. However, you must keep in
mind an important fact. When you enable debugging, the LabWindows/CVI environment
keeps track of the sizes of strings and arrays. If it detects any attempt to access a string or array
beyond its boundary, the environment halts the program and informs you. It is important to
remember that this feature works only when you execute source code in the
LabWindows/CVI development environment. The string functions can write beyond the end
of a string or array without detection, resulting in corruption of memory. Therefore, you must
use the Formatting and I/O functions on strings and arrays with caution.
In addition to the return codes, the GetFmtErrNdxand NumFmtdBytesfunctions
return information on how the last scanning and formatting function executed. The
GetFmtIOErrorfunction returns a code that contains specific error information on the last
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Formatting and I/O Library function that performed file I/O. The GetFmtIOErrorString
function converts this code into an error string. Refer to the LabWindows/CVI Standard
Library Reference Manual for more information.
Utility Library
Utility Library functions report error codes as return values. You can check each individual
function description in the LabWindows/CVI Standard Libraries Reference Manual or in the
LabWindows/CVI function panel help to determine the error conditions that can occur in each
function.
ANSI C Library
Some of the ANSI C library functions report error codes as return values. Some functions also
set the global variable errno. Generally, the functions do not clear errnowhen they return
successfully. To learn more about these values, you can consult a publication such as C: A
Reference Manual cited in the Related Documentation section of About This Manual. Also,
you can use the LabWindows/CVI function panel help to determine the error conditions that
can occur in each function.
LabWindows/CVI Instrument Drivers
Instrument drivers from National Instruments use a standard status reporting scheme.
Functions report error codes as return values, and you can check each function individually
in the LabWindows/CVI function panel help to determine the error conditions that can occur
in each function.
Instrument drivers that comply with the VXIplug&play standard contain two error reporting
functions. Prefix_error_query, where Prefixis the instrument prefix, allows you to
query the error queue in the physical instrument. If the instrument does not have an error
queue, Prefix_error_queryreturns the VI_WARN_NSUP_ERROR_QUERYwarning code
from the VISA Library. Prefix_error_messagetranslates the error and warning codes
that the other instrument driver functions return into descriptive strings.
IVI instrument drivers are VXIplug&play compliant and so contain the
Prefix_error_queryand Prefix_error_messagefunctions. In addition, IVI
instrument driver functions sometimes also provide a secondary error code or an elaboration
string to give you additional information about an error condition. You can use
Prefix_GetErrorInfoto obtain the primary error code, secondary error code, and the
elaboration string for the first error that occurred on a particular instrument session or in the
current thread since you last called Prefix_GetErrorInfo. You also can use the
Prefix_GetAttributefunction to obtain each of these data items, individually, for the
most recent function call on a particular instrument session.
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A
Errors and Warnings
This appendix contains an alphabetized list of compiler warnings, compiler errors, link errors,
DLL loading errors, and external module loading errors generated by LabWindows/CVI.
Table A-1. Error Messages
Error Message
Type Error
Comment
# flag is valid only
with o, x, e, f, and g
specifiers.
Non-Fatal
Run-time Error
Ensure that you use the correct format
specifier, and that no extra characters exist
before the format specifier.
#elif missing constant
expression.
Compile
Error
Ensure that a conditional expression follows
#elifon the same line.
#if missing constant
expression.
Compile
Error
Ensure that a conditional expression follows
#ifon the same line.
#ifdef expects an
identifier.
Compile
Error
Ensure that an identifier follows #ifdefon
the same line.
#ifndef expects an
identifier.
Compile
Error
Preprocessor conditional directive #ifndef
requires an identifier following it on the
same line. Make sure that an identifier
follows #ifndefon the same line.
#line directive cannot
specify line 0.
Compile
Error
#linepreprocessor directive requires a
non-zero line number value.
#line directive cannot
specify line greater
than 32767.
Compile
Error
#linepreprocessor directive cannot set the
line greater than 32,767.
#line directive expects
numeric argument.
Compile
Error
#linepreprocessor directive requires a line
number value to be specified following
#line.
## at beginning of macro
definition.
Compile
Error
##preprocessing token is at the beginning of
a macro definition. Ensure that a
preprocessing token precedes ##.
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
## at end of macro
definition.
Compile
Error
##preprocessing token is at the end of a
macro definition. Ensure that a
preprocessing token(s) follows ##.
, or ) expected.
Compile
Error
Ensure that the function macro argument list
terminates with a )and that a , separates all
the macro arguments.
0 flag is not valid with
c, s, p, and n
modifiers.
Non-Fatal
Run-time Error
Use of an incorrect format specifier or use of
a field width starting with 0might cause this
error.
Aborted load of library
FILE.
Link Error
Link Error
Link Error
Library load operation aborted. A more
specific diagnostic of the library load error
precedes this message.
Aborted load of member
NAME from library FILE.
Library member load operation aborted. A
more specific diagnostic of the library
member load error precedes this message.
Aborted load of object
module FILE.
Object file load aborted. A more specific
diagnostic of the object file load error
precedes this message.
Absolute segments not
supported: segment name
NAME.
PC/Windows
Load Error
OMF object file contains a segment to load
at an absolute address.
Anonymous enum declared
inside parameter list
has scope only for this
declaration.
Compile
Warning
Enumeration declared in the parameter list
has scope only within the parameter list. As
a result, its type is incompatible with
all other types. You must declare the
enumeration type before declaring function
types that use it.
Anonymous struct
declared inside
parameter list has scope
only for this
Compile
Warning
Structure declared in the parameter list has
scope only within the parameter list. As a
result, its type is incompatible with all other
types. You must declare the structure type
before declaring function types that use it.
declaration.
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Anonymousuniondeclared
inside parameter list
has scope only for this
declaration.
Compile
Warning
Union declared in the parameter list has
scope only within the parameter list. As a
result, its type is incompatible with all other
types. You must declare the union type
before declaring function types that use it.
Argument 4 must be 0
or 1.
Fatal
Run-time Error
Value of the argument to the library function
must be 0or 1.
Argument NUMBER must be
0, 1, or 2.
Fatal
Run-time Error
Value of the argument to the library function
must be 0, 1, or 2.
Argument must be a
function pointer to the
correct type of callback
function.
Non-Fatal
Run-time Error
Argument to the function is not a pointer to
the expected type of callback function.
Argument must be an open
stream.
Fatal
Run-time Error
Argument to the I/O library function must be
one of the standard streams (stdin,
stdout, stderr) or a stream you open with
the fopen()or freopen()functions.
Argument must be
character.
Fatal
Run-time Error
Value of the argument to the library function
must be less than 256.
Array argument too
small.
Fatal
Run-time Error
Library function requires an array that is
larger than the specified argument. Make
sure you declare or allocate the array with
sufficient elements for the function call.
Array argument too small
(NUMBERbytes).Argument
must contain at least
NUMBER bytes (NUMBER
elements).
Fatal
Run-time Error
Library function requires an array that is
larger than the specified argument. Make
sure you declare or allocate the array with
the number of elements this error message
reports.
Array index (NUMBER) too
Non-Fatal
You indexed an array past the last element.
large (maximum: NUMBER). Run-time Error
Assertion error:
EXPRESSION.
Fatal
Run-time Error
Value of the argument EXPRESSIONto the
Standard C Library macro assertis 0.
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Assignment between
TYPE and TYPE is
compiler-dependent.
Compile
Warning
Although allowed, use caution because an
assignment of an integertype expression
value to an enumtype target might not
correspond to any known enumeration
constant for that enumtype. Depending on
the enumeration, the size of the enumtype
can be 1, 2, or 4 bytes and therefore may be
incapable of representing all integer values.
Assignment of invalid
pointer value.
Non-Fatal
Run-time Error
Value you assigned to a pointer is an invalid
pointer value. Check the right side of the
assignment to determine if it is the result of
a previous invalid pointer operation.
Assignment of
Non-Fatal
Run-time Error
Value you assigned to the pointer refers to an
invalid location, which is NUMBERbytes
before an array. The right side of the
assignment is probably the result of previous
illegal pointer arithmetic.
out-of-bounds pointer:
NUMBER bytes before
start of array.
Assignment of
Non-Fatal
Run-time Error
Value you assigned to the pointer refers to an
invalid location, which is NUMBERbytes past
the end of an array. The right side of the
assignment is probably the result of previous
illegal pointer arithmetic.
out-of-bounds pointer:
NUMBER bytes past end of
array.
Assignment of pointer to
freed memory.
Non-Fatal
Run-time Error
Value you assigned to the pointer is invalid
because it refers to a location in dynamic
memory that the freefunction deallocated.
After memory is free, all pointers into that
block of memory are invalid.
Assignment of
uninitialized pointer
value.
Non-Fatal
Run-time Error
Value you assigned to the pointer is invalid
because it was not initialized. The right side
of the assignment is probably an
uninitialized local variable or an object in
dynamic memory that you allocated with
malloc. Initialize local variables and
dynamic memory before you use them.
callocboth allocates and initializes
dynamic memory.
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Assignment to const
identifier NAME.
Compile
Error
constvariables or parameters are read-only
values that you cannot modify once
initialized. Ensure that no assignment
operations modify the identifier.
Assignment to const
location.
Compile
Error
constvariables or parameters are read-only
values that you cannot modify once
initialized. Ensure that no assignment
operations modify the lvalue(such as an
array reference, or a pointer dereference)
that specifies the constlocation.
Attempt to free invalid
pointer expression.
Fatal
Run-time Error
Pointer value you passed to the free
function is invalid. It is probably the result of
a previous invalid pointer operation.
Attempt to free pointer
to freed memory.
Fatal
Run-time Error
Pointer value you passed to the free
function refers to a location in dynamic
memory that you already deallocated.
Attempt to free
uninitialized pointer.
Fatal
Run-time Error
Pointer value you passed to the free
function is invalid because you did not
initialize it. It is probably an uninitialized
local variable. Initialize local variables
before you use them.
Attempt to read beyond
end of array.
Non-Fatal
Run-time Error
Source array is not large enough to satisfy
the destination specifiers.
Attempt to read beyond
end of string.
Non-Fatal
Run-time Error
Source string is not large enough to satisfy
the destination specifiers.
Attempt to realloc
invalid pointer
expression.
Fatal
Run-time Error
Pointer value you passed to the realloc
function is invalid. It is probably the result of
a previous invalid pointer operation.
Attempt to realloc
pointer to freed memory. Run-time Error
Fatal
Pointer value you passed to the realloc
function refers to a location in dynamic
memory that you already deallocated.
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Attempt to realloc
uninitialized pointer.
Fatal
Run-time Error
Pointer value you passed to the realloc
function is invalid because you did not
initialize it. It is probably an uninitialized
local variable. You must initialize local
variables before you use them.
Attempt to write beyond
end of array.
Non-Fatal
Run-time Error
Output array is smaller than the given format
specifiers and input parameters require.
Attempt to write beyond
end of string.
Non-Fatal
Run-time Error
Output string is smaller than the given
format specifiers and input parameters
require.
b modifier must precede
o modifier.
Non-Fatal
If both the band omodifiers are present, the
Run-time Error bmodifier must precede the omodifier.
Bad BSS section
encountered while
readingexternalmodule:
FILE.
Object Load
Error
Object module is corrupted or is
of a type that you cannot load into
LabWindows/CVI.
Bad COFF Library header. Object Load
Library file you are loading is either
corrupted or not in the COFF format.
Error
Bad COFF Library member
header.
Object Load
Error
COFF library you are loading contains a
module that is corrupted or in an invalid
format.
Bad location code: OMF
record position NUMBER:
OMF record type NAME.
Link Error
Link Error
Object module is corrupted or is of a type
that you cannot load into LabWindows/CVI.
Bad magic number
encountered while
readingexternalmodule:
FILE.
Object module is corrupted or is of a type
that you cannot load into LabWindows/CVI.
Bad method: OMF record
position NUMBER: OMF
record type NAME.
Link Error
Link Error
Object module is corrupted or is of a type
that you cannot load into LabWindows/CVI.
Bad name: OMF record
position NUMBER: OMF
record type NAME.
Object module is corrupted or is of a type
that you cannot load into LabWindows/CVI.
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Bad OMF record at
position NUMBER: OMF
record type NAME.
PC/Windows
Load Error
OMF object file contains an unknown object
record. Make sure that the object file is OMF
and conforms to the 32-bit format
LabWindows/CVI supports.
Bad relocation record
encountered while
readingexternalmodule:
FILE.
Link Error
Object module is corrupted or is of a type
that you cannot load into LabWindows/CVI.
Bad OMF record at
position NUMBER: OMF
record type NAME.
PC/Windows
Load Error
OMF object file contains an unknown object
record. Make sure that the object file is OMF
and conforms to the 32-bit format
LabWindows/CVI supports.
Byte ordering is
invalid.
Non-Fatal
Run-time Error
Byte ordering that the omodifier specifies is
not valid for the size of the integer. The
number of digits following the omust match
the size of the integer, and the digits must fall
in the range zero to size of the integer–1.
c modifier valid only
Non-Fatal
cmodifier is only valid for the lformat
with l format specifier. Run-time Error
specifier.
The callback function,
NAME, specified in the
UIR file, does not have
required prototype.
Non-Fatal
Run-time Error
You specified the NAMEfunction as a
callback function for an item in a user
interface resource file, but it does not have
the correct type to be a callback function.
Callback functions must have one of the
callback types specified in the user interface
library header. The function will not be
called.
The callback function,
NAME, specified in the
UIR file, is not a known
function.
Non-Fatal
Run-time Error
You specified the NAMEfunction as a
callback function for an item in a user
interface resource file, but the function does
not exist.
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Callingconventionshave
no effect on variables;
calling convention
ignored. The position of
the calling convention
modifier may be
Compile
Warning
You placed a calling convention keyword
before a variable name.
For function pointers, you must place the
calling convention to the left of the "*", for
example:
incorrect.
int (__cdecl * funptr)();
Cannot concatenate wide
and regular string
literals.
Compile
Warning
Make sure the string literals you concatenate
are either both wide string literals or regular
string literals.
Cannot free: memory not
allocated by malloc() or
calloc().
Fatal
Pointer value you passed to the function
Run-time Error freeis invalid because it does not point to
dynamic memory allocated by mallocor
calloc. freecan deallocate only pointers
you obtain from one of these two functions.
Cannot generate glue for
a function without a
prototype: NAME.
Glue Code
Generation
Error
In order to generate glue code for a DLL
function, you must specify a complete
prototype for the function. You must specify
the types of the parameters in the prototype.
Cannot generate glue for
a static function:
FUNCTION.
Glue Code
Generation
Error
You cannot export static functions in a DLL;
so it is useless to generate glue code for
them.
Cannot generate glue for
a variable argument
function: FUNCTION.
Glue Code
Generation
Error
In LabWindows/CVI for Windows 3.1, you
cannot use DLL functions that accept a
variable number of arguments.
Cannot initialize
undefined TYPE.
Compile
Error
You attempted to initialize a declaration of
an incomplete structor uniontype, such
as a structor uniontype whose members
you have not yet specified. Ensure that the
initialization appears after the full struct or
union declaration.
Cannot link variable
NAME to import library
without__importkeyword
in declaration.
Link Error
Variable that you have declared as externis
defined in a DLL import library, but you did
not include the __importqualifier in the
declaration.
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Cannot link variable
NAME to import
library without
declspec(dllimport)
keyword in declaration.
Link Error
Variable that you have declared as externis
defined in a DLL import library, but you did
not include the declspec(dllimport)
qualifier in the declaration.
Case label must be a
constant integer
expression.
Compile
Error
Case labels must be known integer values at
compile time; make sure the case label
conforms to the requirements for a constant
integer expression.
Cast from TYPE to TYPE
is illegal in constant
expressions.
Compile
Error
You cannot cast a pointer type to arithmetic
type in a constant expression.
Cast from TYPE to TYPE
is illegal.
Compiler Error
ANSI C does not allow a cast between the
two types.
COFF Name too long.
Object Load
Error
COFF object or library you are loading
contains a symbol name that is longer than
the maximum legal length.
Comparison involving
null pointer.
Non-Fatal
Run-time Error
One of the pointer expressions in the
comparison has the value NULL. Both
expressions in pointer comparisons must
point into the same array object.
Comparison involving
uninitialized pointer.
Non-Fatal
Run-time Error
One of the pointer expressions in the
comparison is invalid because you did not
initialize it.
Comparison of pointers
to different objects.
Non-Fatal
Run-time Error
Pointer expressions in the comparison point
to two distinct objects. Both expressions in
pointer comparisons must point into the
same array object.
Comparison of pointers
to freed memory.
Non-Fatal
Run-time Error
One of the pointer expressions in the
comparison is invalid because it refers to a
location in dynamic memory that you
deallocated with the freefunction. Once
you free the memory, all pointers into that
block of memory become invalid.
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Compound statements
nested too deeply.
Compile
Error
Program has exceeded the compiler
limitations on the number of nested
compound statements; reduce the depth of
the nested compound statements in the
program.
Conditional inclusion
nested too deeply.
Compile
Error
Program has exceeded the compiler
limitations on the number of nested
conditional preprocessor directives; reduce
the depth of the conditional preprocessor
directives nested in the program.
Conflicting GRPDEFs:
group name NAME.
Link Error
Object module is probably corrupted.
Conflicting argument
declarations for
function FUNCTION.
Compile
Error
Arguments of the named function prototype
declaration do not match those for the
old-style function definition of the same
name; ensure that the function declaration
matches that of the old-style function
definition. A better course is to change the
old-style function definition to a new-style
definition that matches the function
prototype declaration.
Constantexpressionmust
be integer.
Compile
Error
Constant integer expression is expected in
this context. Ensure the expression conforms
to the semantics of a constant expression that
computes an integer value.
Conversion from
TYPE to TYPE is
compiler-dependent.
Compile
Warning
Avoid converting between a function pointer
and other types of pointers, because you
should not access functions as data, and you
cannot execute data as functions.
Could not allocate stack
space. Try decreasing
the Maximum stack size
option in the Run
Fatal
Run-time Error
There is insufficient memory to allocate the
Maximum Stack Size you have specified.
LabWindows/CVI allocates the maximum
size on the stack at the beginning of
execution.
Options dialog.
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Could not find the DLL
header file HEADER FILE. Generation
Glue Code
LabWindows/CVI could not find the file that
contains the prototypes for the functions in
the DLL. When generating glue code, ensure
that you specify the correct filename. When
loading a DLL, ensure that a header file with
the same base name as the DLL exists.
Error
d modifier not valid in
Fmt/FmtOut/FmtFile.
Non-Fatal
Run-time Error
dmodifier cannot be used in Fmt, FmtOut,
or FmtFile.
Declaration of NAME does
not match previous
declaration at POSITION.
Compile
Error
You declared a variable or function twice,
and its type in the first declaration does not
match its type in the second declaration.
Declared parameter NAME
is missing.
Compile
Error
Declaration for a parameter in an old style
parameter list is missing, or the declaration
does not match to any parameter name in the
list. Ensure that the names in the old-style
function definition have corresponding
parameter declarations. A better course is to
convert the old-style function definition to
the new-style function definition requiring
prototypes.
"defined" expects an
identifier argument.
Compile
Error
Preprocessor defined()operator requires
a single identifier argument; ensure that you
use an identifier and not an expression.
Dereference of a NUMBER
byte object where only
NUMBER bytes exist.
Fatal
Run-time Error
Pointer expression you dereferenced points
to an object that is smaller than the type of
the dereference. For example, if an int
pointer points to an object of type char, you
cannot dereference the pointer because it
points to only 1 byte, whereas an int
requires 4 bytes.
Dereference of data
pointer used as a
function.
Fatal
Run-time Error
You converted a data pointer to a function
pointer and then dereferenced it. You can
examine or modify data, but you cannot
execute it as a function.
© National Instruments Corporation
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Dereference of function
pointer used as data.
Fatal
Run-time Error
You converted a function pointer to a
non-function pointer and then dereferenced
it. You can only execute functions and access
them as data.
Dereference of invalid
pointer expression.
Fatal
Run-time Error
Pointer expression you dereferenced is
invalid. It is probably the result of a previous
invalid pointer operation.
Dereference of null
pointer.
Fatal
Run-time Error
Pointer expression you dereferenced has the
value NULLand cannot be dereferenced.
Dereference of
Fatal
Run-time Error
Pointer expression you dereferenced is
invalid because it refers to a location before
the start of an array. The error message
shows the number of bytes and the number
of array elements in the array. The
out-of-bounds pointer:
NUMBER bytes (NUMBER
elements) before start
of array.
expression is probably the result of previous
illegal pointer arithmetic.
Dereference of
Fatal
Run-time Error
Pointer expression you dereferenced is
invalid because it refers to a location past the
end of an array. The error message shows the
number of bytes and the number of array
elements past the end of the array. The
expression is probably the result of previous
illegal pointer arithmetic.
out-of-bounds pointer:
NUMBER bytes (NUMBER
elements) past end of
array.
Dereference of pointer
to freed memory.
Fatal
Run-time Error
Pointer expression you dereferenced is
invalid because it refers to a location in
dynamic memory that you deallocated with
the freefunction. Once memory is free, all
pointers into that block of memory become
invalid.
Dereferenceofunaligned
pointer.
Fatal
Run-time Error
[UNIX only]
Pointer expression you dereferenced is
invalid because it points to an address that
does not have the proper alignment for the
type of the dereferenced object.
SPARCstation architecture requires that
16-bit objects be halfword aligned, 32-bit
objects be word aligned, and 64-bit objects
be doubleword aligned.
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Dereference of
Type Error
Comment
Fatal
Run-time Error
Pointer expression you dereferenced is
invalid because you did not initialize it. It is
probably an uninitialized local variable. You
must initialize local variables before you use
them.
uninitialized pointer.
Duplicate case label
NAME.
Compile
Error
Case label value appears more than once in
the switch statement. Eliminate any
duplicate case label values in the switch
statement.
Duplicatedefinitionfor
NAMEpreviouslydeclared
at POSITION.
Compile
Error
You redeclared a previously defined
parameter name; eliminate one of the
parameter declarations.
Duplicate field name
NAME in TYPE.
Compile
Error
You have already declared the member name
of the structor uniontype. Eliminate one
of the member declarations from the struct or
union type declaration.
Dynamic memory is
corrupt.
Fatal
Run-time Error
LabWindows/CVI encountered corrupt data
while allocating or freeing dynamic
memory.
Empty declaration.
Compile Error
or Warning
You did not declare an object or type. It is an
error if the empty declaration appears in the
context of an old-style parameter
declaration.
Elf library is out of
date.
Object Load
Error
LabWindows/CVI expects a more recent
version of the shared library (libelf.so)
that it uses to load ELF objects. As a result,
LabWindows/CVI is unable to read or write
object and library files.
'enum NAME' declared
inside parameter list
has scope only for this
declaration.
Compile
Warning
Enumeration you declared in the parameter
list has scope only within the parameter list.
As a result, its type is incompatible with all
other types. You must declare the
enumeration type before you declare
function types that use it.
© National Instruments Corporation
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Error exists in the format string at index
Error at or near
character NUMBER in the
format string: STRING.
Non-Fatal
Run-time Error NUMBER. NUMBERis 1-based.
Error in Elf Library
encountered while
readingexternalmodule:
NAME.
Object Load
Error
Object module is corrupted or is of a type
that LabWindows/CVI cannot load.
Error: compiling FILE
for DLL exports.
DLL Import
Library
Creation Error
When creating a DLL using the Include File
method for specifying exported symbols,
an error occurred while compiling the
include file.
Error:Incompatibletype
for function or variable
NAME in header FILE used
to specify exports.
DLL Link Error When creating a DLL using the Include File
method for specifying exported symbols, the
type of the symbol in the include file did not
match the type in the source file.
Expecting an enumerator
identifier.
Compile
Error
Compiler expects an enumeration constant
identifier after the opening {in an enumtype
declaration.
Expecting an identifier. Compile
Compiler expects an identifier in the current
syntactic context. Check the syntax of the
declaration, statement, or preprocessor
directive.
Error
Expecting integer
constant, push, or pop.
Compile
Error
packpragma requires at least one parameter.
Extra default label.
Compile
Error
defaultlabel has already appeared for this
switch statement. Eliminate the extraneous
defaultlabel.
Extraneous 0-width bit
field TYPE NAME ignored. Warning
Compile
Named bit field has no width and therefore
has no storage allocated to it.
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Extraneous formal
parameter
specification.
Compile
Error
This error occurs when the compiler is
processing what it assumes to be an old-style
function declaration and encounters what it
assumes to be the function’s parameter
names. If this is an old-style function
declaration, make sure that the parameter
names appear only in the function definition
and not in any declaration of that function. If
this is a new-style function declaration
(prototype), then probably the identifier that
the compiler assumes to be a parameter
name is really a typedef name. Make sure
that you previously declared the identifier as
a typedef.
Extraneous identifier
NAME.
Compile
Error
Identifier appears in a context where the
compiler expects a type name, such as in a
cast operation or as the operand of
sizeof(). Syntactically, a type name is a
declaration of a function or an object of that
type that omits the identifier.
Extraneous return value. Compile
Return statement appears in a void function
and therefore no return value is necessary;
eliminate the expression from the return
statement.
Error
Failed to load DLL FILE. Link Error
LabWindows/CVI could not find the DLL.
Ensure that it is in one of the default
directories searched by Microsoft Windows,
or that it includes a complete path name.
Failed to open external
module.
Object Load
Error
LabWindows/CVI could not open the
external module for loading. Ensure that the
external module has read access and that you
did not inadvertently rename or delete it.
Field name expected.
Compile
Error
The compiler expects an identifier to follow
a .or –>.
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Field name missing.
Compile
Error
Identifier is missing from a member (field)
declaration in a structor uniontype
declaration. Make sure that an identifier
follows the member type specifier.
Format string integer is
too big.
Non-Fatal
Run-time Error
Integer used in the format string is too large.
Found TYPE expected a
function.
Compile Error
or Warning
In an expression, the compiler expects the
name of a function or pointer to function to
precede a (. In a #pragmaline, the compiler
expects the name of a function after the
pragmatype.
Functiondefinitionsare
not allowed in the
Compile
Error
Function definitions cannot appear in the
Interactive Execution window.
interactive window.
Function FUNCTION:
(STRING == NUMBER).
Non-Fatal
Run-time Error
Library function could not perform its task.
The integer NUMBERis either the function
return value or the value of a global variable
that explains why the function failed. Refer
to the library function reference material for
more information about the error.
Function FUNCTION has
an unsupported return
type size.
Glue Code
Generation
Error
Glue code generation or the DLL loading
facilities do not support the return type of the
function.
Function requires extra
code to handle
Callbacks: FUNCTION.
Glue Code
Generation
Error
Automatic glue code generation facility
cannot generate complete code for this
function because one of its parameters is a
function pointer or it returns a function
pointer. You must generate and modify the
glue source code.
h modifier is only valid
with d, i, n, o, u, and
x specifiers.
Non-Fatal
Run-time Error
You can only use the hmodifier with integer
format specifiers.
Header name literal
too long.
Compile
Error
Header name length exceeds
implementation limitations. Ensure that the
header name is properly terminated with a >
or a ", or shorten the string literal.
LabWindows/CVI Programmer Reference Manual
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Ill-formed constant
integer expression.
Compile
Error
Constant integer expression that appears in a
preprocessor directive is syntactically
invalid. Check the expression for trailing
tokens.
Ill-formed hexadecimal
escape sequence \xCHAR.
Compile
Error
Ensure that a hexadecimal character
([0–9, a–f, or A–F]) follows the \xescape
sequence introduction.
Ill-formed hexadecimal
escape sequence.
Compile
Error
Ensure that a hexadecimal character
(0–9, a–f, or A–F]) follows the \xescape
sequence introduction.
Illegal argument(s) to
library function.
Fatal
Run-time Error
One or more of the arguments to the library
function are invalid. Refer to the library
documentation for the function.
Illegal case label.
Compile
Error
Case label appears outside the context of a
switch statement. Remove the case label.
Illegal character CHAR.
Compile
Error
Character or character escape sequence
outside the legal character set for an ANSI C
source file appears in a context other than a
character string or character literal.
Illegal continue
statement.
Compile
Error
continuestatement appears outside a loop
statement. Remove the continue
statement.
Illegal default label.
Illegal expression.
Compile
Error
defaultlabel appears outside the context
of a switch statement. Remove the default
label.
Compile
Error
Compiler encountered the wrong type of
token while parsing an expression where it
expected an identifier, string literal, integer
constant, floating constant, or (.
Illegal extern
Compile
Error
No InteractiveExecution window definitions
are visible outside the scope of the
Interactive Execution window. You cannot
initialize external symbols in the Interactive
Execution window.
definition of NAME; all
interactive window
variable definitions
must be static.
© National Instruments Corporation
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Illegalformalparameter
types.
Compile
Error
Parameter type of void appears in a function
prototype declaration that has more than one
argument. Remove the void parameter type
or change the function prototype so that it
contains only the single void parameter type.
Illegal header name;
#include expects "FILE"
or <FILE>.
Compile
Error
Unexpected character follows an #include
where a header filename of the form "FILE"
or <FILE>is expected. It is also possible that
the header filename beginning quote
character is different than the expected
closing quote character, such as <FILE".
Illegal initialization
for NAME.
Compile
Error
Ensure that the initialization is not for a
function declaration rather than a pointer to
a function.
Illegal initialization
for parameter.
Compile
Error
Parameter declarations cannot have default
value initializations in ANSI C. Eliminate
the initialization.
Illegal initialization
for parameter NAME.
Compile
Error
Parameter declarations cannot have default
value initializations in ANSI C. Eliminate
the initialization.
Illegal initialization
of extern NAME.
Compile
Error
You attempted to initialize an extern
declaration that appears in a local scope.
Eliminate the initialization.
Illegal return
type TYPE.
Compile
Error
Function is declared with an illegal return
type, or a return statement expression type is
not the same as the return type of the
function in which it appears. If the
diagnostic is for a function declaration,
ensure that the return type is not an array
type or a function type. If the diagnostic is
for a return statement, the containing
function is probably declared void and can
contain no expression in its return statement.
LabWindows/CVI Programmer Reference Manual
A-18
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Illegal return
type; found TYPE
expected TYPE.
Type Error
Comment
Compile
Error
Return statement expression type is not the
same as the return type of the function in
which it appears. Ensure that the type of the
return expression is consistent (assignment
compatible) with the function return type.
Illegal separator
character or illegal
position of separator
character.
Non-Fatal
Run-time Error
Either the separation characters <and >were
not present in the format string, or they were
in the wrong place.
Illegal source filename
specified for #line;
s-char-sequence
Compile
Error
Only token that can follow the line number
specification in a #linepreprocessor
directive is an optional string literal
expected.
specifying a source filename. A sequence of
tokens also can follow the #linetoken if,
after the compiler performs macro expansion
on the source line, the source line conforms
to one of the two allowable forms of #line
preprocessor directives:
#lineline-number-digit-sequence
#lineline-number-digit-sequence
"filename"
Illegal statement
termination.
Compile
Error
During compilation of a sequence of
statements, the compiler encountered a
token that it expected either to begin a new
statement, begin an elseclause of an if
statement, be a statement label, be a case
label, or terminate a compound statement,
such as }. Depending on the context of the
location of where the compiler issued the
diagnostic, ensure that the statement syntax
is correct for the cases listed above.
Illegal type array
of TYPE.
Compile
Error
You attempted to declare an array of
functions. You probably intended to declare
an array of function pointers instead.
© National Instruments Corporation
A-19
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Illegal type const TYPE. Compile
You used more than one qualifier, such as
constor volatile, in a type specification;
for example, const const int. Do not use
the constand volatilequalifiers more
than once each in the same type.
Error
Illegal type for symbol
'DllMain': TYPE.
Compile
Error
DllMaindoes not conform to the accepted
prototype.
int__stdcall DllMain
(HINSTANCE hinstDLL,
DWORD fdwReason,
LPVOID lpvReserved);
Illegal type for symbol
'WinMain': TYPE.
Compile
Error
WinMaindoes not conform to the accepted
prototype.
int__stdcall WinMain
(HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpszCmdLine,
int nCmdShow);
Illegal type volatile
TYPE.
Compile
Error
You used more than one qualifier, such as
constor volatile, in a type specification;
for example, const const int. Do not use
the constand volatilequalifiers more
than once each in the same type.
Illegal use of type
name NAME.
Compile
Error
You used a typedef name in the context of a
primary expression. If you intended to use a
type cast, parenthesize the typedef name.
Otherwise you must use a macro name,
enumeration constant, variable name, or
function name in this context.
Illegal value matched to
asterisk.
Non-Fatal
Run-time Error
Integer argument that matches to an asterisk
(*) in the format string has an invalid value
given the context in which it appears.
LabWindows/CVI Programmer Reference Manual
A-20
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Illegal variable
Compile
Error
Change the variable declaration to be either
staticor extern.
declaration;onlystatic
and extern variable
classes are valid in the
interactive window.
Import Variables cannot
be used in global
variable
Compile
Error
You used a global variable marked as
__importor declspec(dllimport)in
an initializer of another variable.
initialization.
Include files nested too
deeply.
Compile
Error
Number of nested #includefiles exceeds
compiler limits. Reduce the number of
nested #includepreprocessor directives.
Inconsistentlinkagefor
NAMEpreviouslydeclared
at POSITION.
Compile
Error
Current declaration of the identifier is
inconsistent with a previous declaration of
the same identifier with regard to linkage.
Ensure that all declarations of the identifier
that you intend to be staticdo not conflict
with declarations without the static
keyword in the same scope.
Inconsistent type
declarations for
external symbol NAME in
modules FILE1 and FILE2.
Link Error
You declared two or more external symbols
with the same name but not the same type.
Check each program file that contains an
external declaration of the symbol for type
consistency.
Initializer exceeds
bit-field width.
Compile
Warning
Number of bits necessary to represent the
initialization value of a bit field exceeds its
declared width. The compiler truncates the
initialization value to fit the bit field. The
initialization value must be smaller or the bit
field declaration must be wider.
Initializer must be
constant.
Compile
Error
Initializer must be an expression that
conforms to the semantics for a constant
expression.
Insufficient number of
arguments to FUNCTION.
Compile
Error
Function expects more arguments than you
passed to it. Check the function declaration
for the number of parameters to the function.
© National Instruments Corporation
A-21
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Insufficient system
memory for Interactive
Window
Link Error
There is not enough memory to run the code
in the Interactive Execution window.
Insufficient system
memory for project.
Link Error
Link Error
There is not enough memory to link the
project.
Insufficient user data
memory for project.
There is not enough memory to link the
project.
Invalid hexadecimal
constant.
Compile
Error
A token the compiler assumes to be a
hexadecimal constant is badly formed.
Ensure that token conforms to the syntax for
hexadecimal constants, especially that a
valid hexadecimal digit follows the 0xor
0Xprefix.
Invalid initialization
type; found TYPE
expected TYPE.
Compile
Error
Expression that initializes the object
declaration is type incompatible with the
object. Ensure that the initialization
expression is assignment compatible with
the object type. Ensure that all constituent
values of an aggregate expression match the
corresponding positional types of the
aggregate type, such as member types of a
structor uniontype.
Invalid octal constant.
Compile
Error
A token the compiler assumes to be an octal
constant is badly formed. Ensure that the
token conforms to syntax for octal constants,
especially that a valid octal digit follows the
leading 0prefix.
Invalid operand of unary
&; NAME is declared
register.
Compile
Error
It is illegal to take the address (&prefix
operator) of an object you declare to be of
registerclass. Remove the register
keyword from the object declaration if you
want to apply the address operator to it.
Invalidpointerargument
to library function.
Fatal
Run-time Error
Pointer expression you passed to the library
function is invalid. It is probably the result of
a previous invalid pointer operation.
LabWindows/CVI Programmer Reference Manual
A-22
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Invalid size for a real. Non-Fatal
4 and 8 are the only valid sizes that you can
specify with the bmodifier for the f(real)
specifier.
Run-time Error
Invalid size for an
integer.
Non-Fatal
Run-time Error
1, 2, and 4 are the only valid sizes that you
can specify with the bmodifier for the i, d,
x, o, and cmodifiers.
Invalid storage class.
Compile
Error
externis the only allowable explicit
storage class specifier for a function
declaration that has block scope.
Invalid struct field
declarations.
Compile
Error
Compiler encountered an invalid token while
processing a struct or union type declaration.
The compiler expected a token that begins a
member type specifier where the type
specifier is one of void, char, short, int,
long, float, double,signed, unsigned,
<struct-or-union-specifier>,
<enum-specifier>, or
<typedef-name>.
Invalid type argument
TYPE to sizeof.
Compile
Error
You applied sizeofoperator to a function
type or incomplete struct or union type. A
function type has no size, and the size of an
incomplete struct or union type is unknown
before its full declaration.
Invalid type
specification.
Compile
Error
Combination of type specifiers is
incompatible. You can use the type specifier
shortonly in combination with int. You
can use the type specifier longonly in
combination with intand double. You can
use the type specifiers signedand
unsignedonly in combination with one
of the basic integer types (char, short,
int, long).
© National Instruments Corporation
A-23
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Invalid union field
declarations.
Compile
Error
Compiler encountered an invalid token while
processing a struct or union type declaration.
The compiler expected a token that begins a
member type specifier where the type
specifier is one of void, char, short, int,
long, float, double, signed, unsigned,
<struct-or-union-specifier>,
<enum-specifier>, or
<typedef-name>.
Invalid use of TOKEN.
Compile
Error
This error occurs during compilation of a
type specification. The specified TOKENis
not valid in the context of the type specifier.
Two common errors are use of a storage
class other than registerfor a parameter
declaration and using the storage class
registerfor a global object declaration.
l format specifier not
valid in
Non-Fatal
You can use the lformat specifier only in
Run-time Error Scan, ScanOut, and ScanFile.
Fmt/FmtOut/FmtFile.
l modifier is only valid
with d, i, n, o, u, and
x specifiers.
Non-Fatal
Run-time Error
lformat specifier is valid only for integer
format specifiers.
L modifier is only valid
with e, f, and g
specifiers.
Non-Fatal
Run-time Error
Lmodifier, which specifies that the argument
is a long double, can be used only in the
floating point formats.
l modifier is only valid
with e, f, g, d, i, n, o,
u, and x specifiers.
Non-Fatal
Run-time Error
lformat specifier is valid only for integer
and real format specifiers.
Left operand of –> has
incompatible type TYPE.
Compile
Error
Left operand of the –>dereference operation
is either not a pointer to structor union
type, or it is not a pointer type at all.
Left operand of . has
incompatible type TYPE.
Compile
Error
Left operand of the .member selection
operation must be a structor uniontype.
LabWindows/CVI Programmer Reference Manual
A-24
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Library function error
(STRING == NUMBER).
Non-Fatal
Run-time Error
Library function could not perform its task.
The integer NUMBERis either the function
return value or the value of a global variable
that explains why the function failed. Refer
to the library function reference material for
more information about the error.
Lvalue required.
Compile
Error
An lvalue is required in this context. Ensure
that the expression conforms to the
semantics of an lvalue.
Macro expansion too
large.
Compile
Error
Macro expansion has exceeded the compiler
implementation size limitation.
Macro parameter must
follow # operator.
Compile
Error
#operator requires that a macro parameter
immediately follow it in a macro
replacement list.
Matching push not
encountered or already
popped.
Compile
Error
packpragma used a named pop that does not
balance with the push of the same name.
Missing { in
initialization of TYPE.
Compile
Error
Initialization of a struct, union, or array
type, is missing a starting {for an aggregate
initialization value.
Missing #endif
Compile
Error
#if, #ifdefpreprocessor directive must
have a corresponding #endifin the same
source file.
Missing #include file
name; #include expects
"FILE" or <FILE>.
Compile
Error
No include filename follows the #include
preprocessor directive. Ensure that a
filename of the correct form follows
#includeor that any macro that follows
#includeexpands into the correct form for
an include filename.
Missing '.
Compile
Error
Termination single quote character 'is
missing from a character or wide character
literal.
Missing CHAR.
Compile
Error
Check for unterminated string or character
literal.
© National Instruments Corporation
A-25
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Missing argument to
variable argument
function.
Fatal
Run-time Error
Variable argument function requires at least
one argument beyond the last formal
parameter.
Missing array size.
Compile
Error
You attempted to define a block scope object
or type that is an array which has an element
type that is an incomplete array type, such as
an array with unspecified size. The array
element type must be a complete array type,
such as an array type with a known size.
Missing format string
integer.
Non-Fatal
Run-time Error
Integer that corresponds to an asterisk in a
format string is missing. Incorrect ordering
of the arguments can cause this. This integer
must precede the actual argument.
Missing identifier.
Compile
Error
Identifier that specifies the object name is
missing from the object declaration. Ensure
that an identifier follows the object type
specifier.
Missing label in goto.
Compile
Error
gotostatement is missing an identifier label.
Missing parameter name
to function FUNCTION.
Compile
Error
Parameter list of the function definition is
missing an identifier for one of its parameter
declarations. All parameter declarations for
a function definition must include an
identifier except for the special case of a
parameter list consisting of a single
parameter of type void, in which there must
not be an identifier.
Missing parameter type.
Compile
Error
Type specifier is missing from a parameter
declaration in a new-style (prototype)
function declaration. Ensure that the
function declaration is not mixing old-style
parameter declarations with new-style
(prototype) declarations.
LabWindows/CVI Programmer Reference Manual
A-26
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Missing prototype.
Compile
Error
Function declaration or call is for a function
without prototype declaration information.
The compiler issues the diagnostic if the
Require Function Prototypes compiler
option is enabled.
Missing return value.
Missing return value.
Fatal
Run-time Error
Function does not return a value, although
you declared it with a return type. If you did
not intend for the function to return a value,
you must declare it as a voidfunction.
Otherwise, you must use a return
statement to return a value.
Compile
Warning
Non-void function does not return a value.
Add a return statement with an expression of
the function return type. The compiler issues
the diagnostic if the Require Return Value
for Non-void Functions compiler option is
enabled.
Missing right
bracket (]).
Fatal
Run-time Error
Format string has mismatched brackets.
Missing struct tag.
Compile
Error
Tag name is missing from an incomplete
struct or union declaration.
Missingterminatingnull
in string argument.
Fatal
Run-time Error
Library function expects a string argument,
but the argument you passed points to an
array of characters that is not
null-terminated.
Missing union tag.
Compile
Error
Tag name is missing from an incomplete
struct or union declaration.
Multiply defined symbol
NAME in modules FILE1
and FILE2.
Link Error
The files being linked contain more than one
definition for NAME.
Naked functions are not
supported.
Compile
Error
LabWindows/CVI does not work with the
nakedkeyword.
NAME is a predefined
macro and cannot be the
subject of an #undef.
Compile
Error
Make sure that the name you specify for the
#undefpreprocessor directive is not that of
a predefined macro.
© National Instruments Corporation
A-27
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
No data relocation
section found for
external module: FILE.
Link Error
External object module does not contain the
relocation information necessary to link it in
with the rest of the project. You cannot load
an executable as an object module.
No data section
found for external
module: FILE.
Link Error
External object module does not contain the
initialized data necessary to link it in with
the rest of the project. Ensure that you built
the external object file correctly.
No pack settings
currently pushed.
Compile
Error
packpragma used a pop when there were no
pushes.
No symbol table
found for external
module: FILE.
Link Error
Link Error
Link Error
External object module does not contain the
symbol table information necessary to link it
in with the rest of the project. Ensure that
you built the external object file correctly.
No text relocation
section found for
external module: FILE.
External object module does not contain the
relocation information necessary to link it in
with the rest of the project. You cannot load
a linked executable as an object module.
No text section
found for external
module: FILE.
External object module does not contain the
initialized instruction data necessary to link
it in with the rest of the project. Ensure that
you built the external object file correctly.
Non-terminated
address list.
Fatal
Run-time Error
You attempted to pass an address list array
that you did not terminate with –1to a
GPIB-488.2 function that expects the array
to terminate with –1.
Not enough parameters.
Non-Fatal
Run-time Error
Number of arguments the format string
expects is more than the number of
arguments you passed in.
Not enough space for
casting expression
to TYPE.
Non-Fatal
Block of memory you obtained from
Run-time Error mallocor callocis not large enough for a
single object of type TYPEand cannot be cast
to that type.
LabWindows/CVI Programmer Reference Manual
A-28
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Null Pointer.
Type Error
Comment
Fatal
Run-time Error
Pointer expression you passed to the library
function has the value NULL, which is not a
valid value for the function.
Null pointer argument to
library function.
Fatal
Run-time Error
Pointer expression you passed to the library
function has the value NULL, which is not a
valid value for the function.
NUMBER is an illegal
array size.
Compile
Error
Make sure that the size of the array
declaration is > 0.
NUMBER is an illegal bit
field size.
Compile
Error
Make sure that the size you specified for the
bit field is ≥ 0 and ≤ 32.
NUMBER line(s)
truncated. File set to
read-only.
Compile
Error
Occurs when reading in source or include
file. Lines are limited to 254 characters,
where tabs count as 1. Use the editor in
which you created the file to split the line.
Number of arguments
exceed the maximum
supported.
Non-Fatal
Run-time Error
Number of arguments exceeds the maximum
that the formatting functions support.
Number of points is too
large for current
waveform buffer.
Fatal
Message appears when the
Run-time Error numberofPointsparameter of a data
acquisition waveform generation function is
larger than the numberofPointsparameter
to the function which set up the waveform
buffer.
Object module contains
unsupported FAR
pointers.
Object Load
Error
External object module contains FAR
pointers, which you cannot implement in
LabWindows/CVI.
One of the arguments to
FUNCTION has an
unsupported size.
Glue Code
Generation
Error
One of the function arguments has a type that
the LabWindows/CVI glue code generation
and DLL loader do not support.
Only object modules
produced by WATCOM C 386
fully supported.
Link Error
External object module contains OMF
records that LabWindows/CVI does not
recognize or support. Ensure that the object
file was compiled with a Watcom C 386
compiler with the recommended options.
© National Instruments Corporation
A-29
LabWindows/CVI Programmer Reference Manual
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Operands of ‘=‘ have
incompatible calling
conventions.
Compile
Error
Function pointer is assigned an expression
that does not match its calling convention.
Operands of [one from
set of binary operators]
have illegal types TYPE
and TYPE.
Compile
Error
Types of the two operands to the
binary operator are illegal according to the
ANSI C standard.
Operands of [one from
set of binary operators]
have incompatible types.
Compile
Error
Types of the two operands to the binary
operator are not compatible according to the
ANSI C standard.
Operand of unary
OPERATOR has illegal
type TYPE.
Compile
Error
Type of the operand to the unary operator is
not valid.
Out-of-bounds pointer
argument (before start
of array).
Fatal
Run-time Error
Pointer expression you passed to the library
function is invalid because it refers to a
location that is before the start of an array.
The expression is probably the result of
previous illegal pointer arithmetic.
Out-of-bounds pointer
argument (past end of
array).
Fatal
Run-time Error
Pointer expression you passed to the library
function is invalid because it refers to a
location past the end of an array. The
expression is probably the result of previous
illegal pointer arithmetic.
Out-of-bounds pointer
arithmetic:NUMBERbytes
(NUMBERelements)before
start of array.
Non-Fatal
Run-time Error
Pointer arithmetic expression is invalid
because the resulting value refers to a
location before the start of an array. The
error message shows the number of bytes
and number of array elements before the
beginning of the array.
Out-of-bounds pointer
arithmetic:NUMBERbytes
(NUMBER elements) past
end of array.
Non-Fatal
Run-time Error
Pointer arithmetic expression is invalid
because the resulting value refers to a
location past the end of an array. The error
message shows the number of bytes and
number of array elements past the end.
Out of memory for user
protection information.
Fatal
Run-time Error
Could not allocate memory required to store
user protection information.
LabWindows/CVI Programmer Reference Manual
A-30
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Overflow in constant
CONSTANT.
Compile
Warning
Value of a constant or constant expression
exceeds the limits of the type. Ensure that the
value does not exceed the maximum value
for the expression type.
Overflow in constant
expression.
Compile
Warning
Value of a constant or constant expression
exceeds the limits of the type. Ensure that the
value does not exceed the maximum value
for the expression type.
Overflow in floating
constant CONSTANT.
Compile
Warning
Value of a constant or constant expression
exceeds the limits of the type. Ensure that the
value does not exceed the maximum value
for the expression type.
Overflow in hexadecimal
escape sequence.
Compile
Warning
Value of a constant or constant expression
exceeds the limits of the type. Ensure that the
value does not exceed the maximum value
for the expression type.
Overflow in octal escape
sequence.
Compile
Warning
Value of a constant or constant expression
exceeds the limits of the type. Ensure that the
value does not exceed the maximum value
for the expression type.
Overflow in value for
enumeration constant
CONSTANT.
Compile
Error
Value of a constant or constant expression
exceeds the limits of the type. Ensure that the
value does not exceed the maximum value
for the expression type.
Overflowoccurredduring
the conversion of the
int. The absolute value
is too big for the size.
Non-Fatal
Run-time Error
Number was too large to store in the integer
of the specified size.
Overflowoccurredduring
the conversion of the
float. The number is too
big for type float.
Non-Fatal
Run-time Error
Number was too large to store in a 4-byte
real.
Overflowoccurredduring
the conversion of the
int. The signed value is
too big for the size.
Non-Fatal
Run-time Error
Number was too large to store in the integer
of the specified size.
© National Instruments Corporation
A-31
LabWindows/CVI Programmer Reference Manual
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Pack pragma valid values
are 1, 2, 4, 8, and 16.
Compile
Error
packpragma alignment value parameter
must be 1, 2, 4, 8, or 16.
Parameter type
incompatiblewithformat
specifier.
Non-Fatal
Run-time Error
Parameter type is not compatible with the
type that the format string expects.
An argument is either missing or of the
wrong type.
Parametertypemismatch:
expecting TYPE but
found TYPE.
Non-Fatal
Run-time Error
Parameter type does not match the type that
the format string expects. The arguments
might not be in the right order, or an
argument might be missing.
Pointer arithmetic
involving invalid
pointer.
Non-Fatal
Run-time Error
Pointer arithmetic expression is invalid
because one of the subexpressions contains
an invalid pointer.
Pointer arithmetic
involving null pointer.
Non-Fatal
Run-time Error
Pointer arithmetic expression is invalid
because one of the subexpressions contains
the value NULL.
Pointer arithmetic
involving pointer to
freed memory.
Non-Fatal
Run-time Error
Pointer arithmetic expression is invalid
because one of the subexpressions contains a
pointer to dynamic memory that you
deallocated with the freefunction. Once
memory is free, all pointers into that block of
memory are invalid.
Pointer arithmetic
involving pointer to
function.
Non-Fatal
Run-time Error
Pointer arithmetic expression is invalid
because one of the subexpressions is a
function pointer.
Pointer arithmetic
involving uninitialized
pointer.
Non-Fatal
Run-time Error
Pointer arithmetic expression is invalid
because one of the subexpressions contains
an uninitialized pointer. It is probably an
uninitialized local variable.
Pointer comparison
involving address of
nonarray object.
Non-Fatal
Run-time Error
One of the pointer expressions in the
comparison is invalid because it does not
point into an array. Both expressions in
pointer comparisons must point into the
same object.
LabWindows/CVI Programmer Reference Manual
A-32
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Pointer is invalid.
Non-Fatal
Run-time Error
Pointer argument to the function contains an
invalid address.
Pointer points to freed
memory.
Non-Fatal
Run-time Error
Pointer argument to the function points to
memory that you already freed.
Pointer subtraction
involving address of
nonarray object.
Non-Fatal
Run-time Error
One of the pointer expressions in the
subtraction is invalid because it does not
point into an array. Both expressions in
pointer subtractions must point into the same
object.
Pointer to a local is an
illegal return value.
Compile
Error
Value returned from the function is a pointer
to a parameter or local variable. Because the
lifetime of a parameter or local variable ends
when you return from the function, any
pointer to such an object is invalid.
Pointer to a parameter
is an illegal return
value.
Compile
Error
Value returned from the function is a pointer
to a parameter or local variable. Because the
lifetime of a parameter or local variable ends
when you return from the function, any
pointer to such an object is invalid.
Pointer to free memory
passed to library
function.
Fatal
Run-time Error
Pointer expression you passed to the library
function is invalid because it refers to a
location in dynamic memory that you
deallocated with the function free. Once
memory is free, all pointers into that block of
memory are invalid.
pragmapack(pop...)does
not set alignment. Use
separate pack pragma.
Compile
Warning
You used a pragma pop with an alignment
value. Use separate packpragmas for
popping and setting the alignment value.
© National Instruments Corporation
A-33
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Project not linked.
Link Warning
This error occurs when the compiler reports
one or more link errors in the Interactive
Execution window and the project is not in a
linked state. This warning provides a
possible explanation for the link errors. The
Interactive Execution window does not link
to the project unless the project is in a linked
state. If you are referencing project symbols
from the Interactive Execution window, use
the Build Project command from the Build
menu to compile and link the project first.
Qualified function type
ignored.
Compile
Warning
Any qualification of a function declaration is
extraneous but harmless.
Read error.
Link Error
Error has occurred while attempting to read
a file. Ensure that the file has access
permission and that it is in the correct
format.
Redeclaration of ‘%s’
with different calling
convention, previously
declared at %w.
Compile
Error
Function has been redeclared with a different
calling convention.
Redeclaration of macro
parameter NAME.
Compile
Error
Parameter name has already been used once
by the macro. Choose another parameter
name.
Redeclaration of NAME.
Compile
Error
Declared name conflicts with a previous
declaration in the same scope and name
space. You have already used the name in
this scope. Choose another name for this
declaration.
Redeclaration of NAME
previously declared at
POSITION.
Compile
Error
Declared name conflicts with a previous
declaration in the same scope and name
space. You have already used the name in
this scope. Choose another name for this
declaration.
LabWindows/CVI Programmer Reference Manual
A-34
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Redefinition of label
NAME previously defined
at POSITION.
Compile
Error
You already used the statement label in this
function. A statement label must be unique
within the function in which you use it.
Redefinition of
macro NAME.
Compile
Error
Macro has already been defined with a
replacement list different from the current
definition. The same macro definition for a
name may appear in the same file more than
once as long both definitions agree in name
and number of parameters and their
replacement lists are identical.
Redefinition of NAME
previously defined at
POSITION.
Compile
Error
You have already defined the object or
function in the current scope. Eliminate one
of the two definitions.
Reference parameter
expected.
Non-Fatal
Run-time Error
Function expected a pointer but you passed it
a scalar.
Register declaration
ignored for TYPE NAME.
Compile
Warning
registerstorage class conflicts with the
semantics of the type declared for the object.
If you declared the object to be of an array,
struct, or union type, or you qualified it
as volatile, remove the register
keyword from the declaration.
Register declaration
ignored for TYPE
parameter.
Compile
Warning
registerstorage class conflicts with the
semantics of the type you declared for the
parameter prototype. If you declared the
object to be of structor uniontype, or
you qualified it as volatile, remove the
registerkeyword from the prototype
parameter declaration.
Repeat value not valid
with s/l format
specifiers.
Non-Fatal
Run-time Error lformat specifiers.
You cannot use a repeat value with the sand
Result of unsigned
comparison is constant.
Compile
Warning
Result of <UNSIGNED INTEGER
EXPRESSION> ≥ 0always evaluates
to 1.
© National Instruments Corporation
A-35
LabWindows/CVI Programmer Reference Manual
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Segment must be of
class CODE, DATA, BSS,
or STACK: segment
name NAME.
Load Error
External object module contains an
unknown segment class. Object modules
must not contain any specially-named
segments.
Segment must be USE32:
segment name NAME.
Link Error
External object module you loaded contains
unsupported 16-bit segments.
LabWindows/CVI supports only 32-bit
object modules. Ensure that the external
object module was compiled with a 32-bit
compiler.
'signed' type mismatch
between TYPE and TYPE.
Compile
Warning
This warning is issued when the signs of the
lvalue and rvalue expressions in a pointer
assignment operation do not agree. Both
lvalue and rvalue are pointers to integer
types but they point to integer types of
differing signs, which might cause problems
if you later dereference the lvalue. This
diagnostic is issued if you select the Enable
Signed/Unsigned Pointer Mismatch
Warning compiler option.
Simple/Array conflict
with format specifier.
Non-Fatal
Run-time Error
Array you passed to the function matches to
a format specifier for a scalar, or a scalar you
passed to the function matches to a format
specifier for an array.
Size of array of TYPE
exceeds SIZE bytes.
Compile
Error
Size of the array or struct/union type exceeds
the compiler limitation of INT_MAXbytes.
Size of TYPE exceeds
SIZE bytes.
Compile
Error
Size of the array or struct/union type exceeds
the compiler limitation of INT_MAXbytes.
sizeof applied to a bit
field.
Compile
Error
Do not use the sizeof()operation on a
bit-field.
Specified width is too
small to read the
number.
Non-Fatal
Run-time Error
Width you specified for a format specifier
was not large enough to contain a complete
number. Example: you specify a width of 2
for a float, and the number is –.02; the
negative sign and decimal point do not
constitute a valid number.
LabWindows/CVI Programmer Reference Manual
A-36
© National Instruments Corporation
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Stack Overflow.
Fatal
Run-time Error
Program exceeds the stack limit. Change the
size of the stack in the Run Options dialog
box, if you think that the code is executing
correctly. Otherwise, ensure that the
program does not contain any infinite
recursion.
‘struct NAME’ declared
inside parameter list
has scope only for this
declaration.
Compile
Warning
Structure declared in the parameter list has
scope only within the parameter list. As a
result, its type is incompatible with all other
types. You must declare the structure type
before you declare function types that use it.
Structures containing
unspecified size array
fields must contain
other fields.
Compile
Error
Structures that contain arrays with
unspecified size must contain at least
one other non-zero size member.
LabWindows/CVI supports these types
of structures as an extension to the
ANSI C standard.
Subtraction involving
invalid pointer.
Non-Fatal
Run-time Error
One of the pointer expressions in the
subtraction is invalid. It is probably the result
of a previous invalid pointer operation.
Subtraction involving
null pointer.
Non-Fatal
Run-time Error
One of the pointer expressions in the
subtraction has the value NULL. Both
expressions in pointer subtractions must
point into the same array object.
Subtraction involving
uninitialized pointer.
Non-Fatal
Run-time Error
One of the pointer expressions in the
subtraction is invalid because you did not
initialize it.
Subtraction of pointers
to different objects.
Non-Fatal
Run-time Error
Pointer expressions in the subtraction point
to two distinct objects. Both expressions in
pointer subtractions must point into the same
array object.
© National Instruments Corporation
A-37
LabWindows/CVI Programmer Reference Manual
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Subtraction of pointers
to freed memory.
Non-Fatal
Run-time Error
One of the pointer expressions in the
subtraction is invalid because it refers to a
location in dynamic memory that you
deallocated with the function free. Once
memory is free, all pointers into that block of
memory are invalid.
Switch statement with
no cases.
Compile
Warning
Switch statement contains no caseor
defaultlabel.
Symbol NAME defined
in modules FILE and
FILE. In Borland
mode, multiple modules
must not contain
Link Error
In Borland mode, multiple modules must not
contain uninitialized definitions of the same
global variable. Borland creates a separate
variable for each definition.
LabWindows/CVI and other linkers resolve
all definitions to the same variable. If you
want separate variables, use different names
or the “static” keyword. If you want one
variable, change all definitions except one to
“extern” declarations.
uninitialized
definitions of the
same global variable.
Borland creates a
separate variable
for each definition.
LabWindows/CVIandother
linkers resolve all
definitions to the same
variable. If you want
separate variables, use
different names or the
"static" keyword. If
you want one variable,
change all definitions
except one to "extern"
declarations.
Symbol NAME exported
from header FILE not
found in DLL.
DLL Link Error When you used the Include File method for
or Import
specifying the symbols to export from a
DLL, one of the symbols you declared in the
include file was not in the DLL project. Or,
when you created import libraries from an
include file and a DLL, one of the symbols
you declared in the include file was not in
the DLL.
Library
Creation Error.
LabWindows/CVI Programmer Reference Manual
A-38
© National Instruments Corporation
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Syntax error; found
Compile
Syntax error occurred because the compiler
TOKEN1 expecting TOKEN2. Error
found TOKEN1instead of TOKEN2.
The __cdecl calling
convention is not
supportedwithfunctions
returning floats,
doubles, or structures
in WATCOM Compatibility
Mode.
Compile
Error
Function with an explicit __cdeclqualifier
returns a double, floator structure, and
your current compatible compiler is
Watcom. Either remove the qualifier or
change the function.
The callback function,
NAME, differs only by a
leading underscore from
another function or
variable. Change one of
the names for proper
linking.
Non-Fatal
Run-time Error
When trying to match a callback name you
specified in a .uirfile to the callback
function, the compiler found two symbols
that are the same except for a leading
underscore. Resolve this ambiguity by
changing one of the names.
Thread data is not
supported.
Compile
Error
You cannot implement thread-local storage
in LabWindows/CVI.
Too many arguments to
FUNCTION.
Compile
Error
Declaration for function FUNCTIONcontains
fewer parameters than the number of
arguments you passed in this function call.
Too many arguments to
variable argument
function.
Non-Fatal
Run-time Error
You passed more arguments to the variable
argument function than it expected. The
extra arguments do not affect the function
call in any way.
Too many function
parameters.
Compile
Error
Number of parameter declarations exceeds
compiler limitations. Declare the function
with fewer parameters.
Too many initializers.
Compile
Error
Size of the initializer exceeds the size of the
object. Ensure that the initializer matches the
number/size of the object type.
Too many macro
parameters.
Compile
Error
Number of parameter declarations exceeds
compiler limitations. Declare the macro with
fewer parameters.
© National Instruments Corporation
A-39
LabWindows/CVI Programmer Reference Manual
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Too many parameters.
Non-Fatal
Run-time Error
Number of parameters you passed to a
function exceed the number of parameters
the format string expects.
Type error in argument
%d to %s, calling
convention mismatch.
Compile
Error
Function or function pointer you passed to a
function does not have the correct calling
convention.
Type error in argument
NUMBER to NAME; TYPE is
illegal.
Compile
Error
Argument you passed is an illegal array type
or an incomplete type of which the size is
unknown. Ensure that the argument is of a
complete type.
Type error in argument
NUMBER to NAME; found
TYPE expected TYPE.
Compile
Error
You passed an argument that is not type
compatible with the prototype declaration
for the parameter in that position. Ensure
that the actual argument is type compatible
with the parameter declaration.
Type error:
pointer expected.
Compile
Error
Expression you dereferenced with the '*',
'->' or '[]' operator does not have pointer
type.
TYPE is an illegal bit
field type.
Compile
Error
Only intand unsignedtypes are valid for
bit field declarations; ensure that you use one
of these types.
TYPE used as an lvalue.
Compile
Warning
Type that cannot be modified is used as the
target of an assignment. This was probably
caused by an lvalue that is a dereference of
an object declared as (void *).
Unclosed comment.
Compile
Error
Comment is missing the closing
*/ delimiter.
Undeclared identifier
NAME.
Compile
Error
You did not previously declare NAME. You
must declare all names before use. Ensure
that you did not conditionally exclude NAME
from compilation.
LabWindows/CVI Programmer Reference Manual
A-40
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Undefined label NAME.
Compile
Error
You used the label NAMEas the target of a
gotostatement in the function but it never
appears as a statement label. Ensure the label
appears in the same function as the goto
statements of which it is a target. Non-local
gotostatements are illegal.
Undefined size for
TYPE NAME.
Compile
Error
You have defined an object with an
incomplete type. Because the size of an
incomplete type is unknown, storage cannot
be allocated for the object.
Undefined size for
field TYPE.
Compile
Error
Member (field) declaration has no size for
the declared type. You probably declared the
member with an empty structor union
type declaration.
Undefined size for field
TYPE NAME.
Compile
Error
Member (field) declaration has no size for
the declared type. You probably declared the
member with an empty structor union
type declaration.
Undefined size for
parameter TYPE NAME.
Compile
Error
You declared a parameter with an
incomplete type. Because the size of an
incomplete type is unknown, storage cannot
be allocated for the object.
Undefined size for
static TYPE NAME.
Compile
Error
You declared a staticobject with an
incomplete type or without an initialization
expression from which the compiler can
calculate a size for the type. Because the size
of an incomplete type is unknown, you
cannot allocate storage for the object.
Undefined static
TYPE NAME.
Compile
Warning or
Error
You declared the staticfunction but never
defined it. Because a staticfunction is
only visible within the file in which you
declared it, you must define it at some point
within the file in order to use it. If you called
the function anywhere in the file, this
diagnostic is an error. Otherwise it is a
warning.
© National Instruments Corporation
A-41
LabWindows/CVI Programmer Reference Manual
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Undefined symbol NAME.
Link Error
You used a variable or function in the project
but did not define it anywhere.
Unexpected #elif;
#endif expected.
Compile
Error
Compiler encountered an #else
preprocessor directive immediately prior to
this #elifat the same level of conditional
inclusion. Ensure that the conditional
preprocessor #includedirectives at this
level are in the proper order.
Unexpected #elif;
#if not seen.
Compile
Error
Compiler encountered an #elif
preprocessor directive but it has not yet seen
a beginning #if, #ifdef, or ifndefat
this level.
Unexpected #else;
#endif expected.
Compile
Error
Compiler encountered an #else
preprocessor directive immediately
following a prior #elseat the same level of
conditional inclusion. Ensure that the
conditional preprocessor #include
directives at this level are in the proper order.
Unexpected #else;
#if not seen.
Compile
Error
Compiler encountered an #else
preprocessor directive, but it has not yet seen
a beginning #if, #ifdef, or ifndefat
this level.
Unexpected #endif;
no matching#if,#ifdef,
or #ifndef.
Compile
Error
Compiler encountered an #endif
preprocessor directive but has not yet seen a
beginning #if,#ifdef, or ifndefat
this level.
Unexpected EOF.
Load Error
LabWindows/CVI encountered an
unexpected End Of File (EOF) condition
when loading an external object module.
Ensure that the object file has not been
truncated.
Unexpected EOF;
TOKEN expected.
Compile
Error
The compiler encountered an End Of File
(EOF) condition while parsing a syntactic
construct. Ensure that syntactic structure is
complete, such as matching parenthesis and
matching braces.
LabWindows/CVI Programmer Reference Manual
A-42
© National Instruments Corporation
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Unexpected end of format
string.
Non-Fatal
Run-time Error
Format string you passed to the function is
not complete. It is missing a source or
destination format specifier, or contains an
incomplete format specifier.
Unexpected token.
Compile
Error
Compiler encountered an unexpected token
while processing a #definepreprocessor
directive. Check for missing )in your macro
parameter lists.
Unexpected trailing
tokens on directive line
ignored.
Compile
Warning
Preprocessor line contains harmless trailing
tokens that the compiler ignored.
Uninitialized pointer.
Non-Fatal
Run-time Error
You never assigned a value to the pointer
argument you passed to a function.
Uninitialized pointer
argument to library
function.
Fatal
Run-time Error
Pointer expression you passed to the library
function is invalid because you did not
initialize it. It is either a local variable or an
object in dynamic memory that you did not
initialize.
Uninitialized string.
Non-Fatal
Run-time Error
You never assigned a value to the pointer
argument you passed to the library function,
or it is NULL.
'union NAME' declared
inside parameter list
has scope only for this
declaration.
Compile
Warning
Union declared in the parameter list has
scope only within the parameter list. As a
result, its type is incompatible with all other
types. You should declare the union type
before you declare function types that use it.
Unknown enumeration
NAME.
Compile
Error
NAMEis an undeclared enumeration type.
Unknown field NAME
of TYPE.
Compile
Error
Member selection or dereference has
attempted to access an undeclared member,
(field) name of a struct, or uniontype.
Ensure that the member is declared for the
structor uniontype you select or
dereference.
© National Instruments Corporation
A-43
LabWindows/CVI Programmer Reference Manual
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Unknown modifier.
Non-Fatal
Run-time Error
One of the modifiers in a format specifier is
not valid.
Unknown or unsupported
OMF record at position
NUMBER: OMF record type
NUMBER.
Load Error
LabWindows/CVI encountered an unknown
OMF record while loading an external object
module. Ensure that the external object
module was compiled properly.
Unknown size of
type TYPE.
Compile
Error
You performed pointer arithmetic on
operand(s) that are pointers to types of
unknown size. The types are probably
incomplete types or pointer to function
types. Ensure that the pointer types point to
fully declared types and are not pointers to
functions.
Unknown specifier.
Non-Fatal
Specifier in the format specifier is not valid.
Run-time Error
Unnamed pop matching
named push.
Compile
Warning
packpragma used an unnamed pop that
balances a name push.
Unrecognized character
escape sequence.
Compile
Warning
Character escape sequence does not conform
to any known character escape sequence,
octal escape sequence, or hexadecimal
escape sequence.
Unrecognized character
escape sequence CHAR.
Compile
Warning
Character escape sequence does not conform
to any known character escape sequence,
octal escape sequence, or hexadecimal
escape sequence.
Unrecognized
declaration.
Compile
Error
Declaration is unrecognizable. Check the
declaration syntax for the function, object, or
type you want to use.
Unrecognized
preprocessor directive.
Compile
Error
# character begins an unknown preprocessor
directive. Check the spelling of the
preprocessor directive.
Unrecognized statement.
Compile
Error
Statement syntax is unrecognizable. Check
the statement syntax for the type of
statement you want to use.
LabWindows/CVI Programmer Reference Manual
A-44
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Unsigned operand of
unary –.
Compile
Warning
You performed a nonsensical unary negation
operation on an unsigned type. A negation
operation on an unsigned type is not
effective.
Unsupported segment
combinationtypeNUMBER:
segment name NAME.
Load Error
LabWindows/CVI encountered a bad
segment while loading an external object
module. Ensure that the external object
module was compiled properly.
Use of keyword
Compile
Error
Use of a keyword in a variable definition
contradicts a previous definition, for
example:
'__import' contradicts
previous use of keyword
'__export' at POSITION.
int __export x;
int __import x=0;
Use of keyword
Compile
Error
Use of a keyword in a variable definition
contradicts a previous definition, for
example:
'__export' contradicts
previous use of keyword
'__import' at POSITION.
int __import x;
int __export x=0;
Use of keyword
Compile
Error
Use of a keyword in a variable definition
contradicts a previous definition, for
example:
int __declspec(dllexport) x;
int __declspec(dllimport) x=0;
'__declspec(dllimport)'
contradicts previous
use of keyword
'__declspec(dllexport)'
at POSITION.
Use of keyword
Compile
Error
Use of a keyword in a variable definition
contradicts a previous definition, for
example:
int __declspec(dllimport) x;
int __declspec(dllexport) x=0;
'__declspec(dllexport)'
contradicts previous
use of keyword
'__declspec(dllimport)'
at POSITION.
Value parameter
expected.
Non-Fatal
Run-time Error
You passed a pointer for a format specifier
that requires a scalar value.
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Appendix A
Errors and Warnings
Table A-1. Error Messages (Continued)
Error Message
Type Error
Comment
Variables defined as
DLL imports cannot be
defined with an initial
value.
Compile
Error
You assigned an initial value to a variable
defined as a DLL import, for example:
int __import i = 0;
You must initialize the variable in a separate
assignment statement.
VXI address must be a
multiple of 2 for word
transfer.
Fatal
Run-time Error
You attempted to perform VXI word transfer
beginning at an odd address.
VXI address must be a
multiple of 4 for
longword transfer.
Fatal
Run-time Error
You attempted to perform a VXI longword
transfer beginning at an address that is not a
multiple of 4.
w modifier not valid
Non-Fatal
You cannot use the wmodifier with the
with l format specifier. Run-time Error lformat specifier.
Warning: Import
DLL Link
Warning
When creating a DLL using the Symbols
Marked for Export method for specifying
exported symbols, one of the modules was
an object or library file. LabWindows/CVI
does not have sufficient information to
ensure that the import libraries it generates
for all four compatible external compilers
will have the correct names of the symbols in
that module.
libraries other than the
one for the current
compatibility mode may
not work for symbols
exported from an object
file. It is recommended
that you export using
header files instead.
WatchPoint: module name
is not valid.
Watchpoint
Error
Module name you specified in the watch
point is not present in the project or in any of
the loaded instrument drivers.
z modifier only valid if
rep is present.
Non-Fatal
Run-time Error
zmodifier cannot be used if the format
specifier is not for an array.
z modifier required to
match string parameter.
Non-Fatal
Run-time Error
If you want to treat a character string as an
array of another type, you must use the z
modifier. This error also can occur if the
order of the arguments is incorrect, or if an
argument is missing.
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B
Customer Communication
For your convenience, this appendix contains forms to help you gather the information necessary
to help us solve your technical problems and a form you can use to comment on the product
documentation. When you contact us, we need the information on the Technical Support Form and
the configuration form, if your manual contains one, about your system configuration to answer your
questions as quickly as possible.
National Instruments has technical assistance through electronic, fax, and telephone systems to quickly
provide the information you need. Our electronic services include a bulletin board service, an FTP site,
a fax-on-demand system, and e-mail support. If you have a hardware or software problem, first try the
electronic support systems. If the information available on these systems does not answer your
questions, we offer fax and telephone support through our technical support centers, which are staffed
by applications engineers.
Electronic Services
Bulletin Board Support
National Instruments has BBS and FTP sites dedicated for 24-hour support with a collection of files
and documents to answer most common customer questions. From these sites, you can also download
the latest instrument drivers, updates, and example programs. For recorded instructions on how to use
the bulletin board and FTP services and for BBS automated information, call 512 795 6990. You can
access these services at:
United States: 512 794 5422
Up to 14,400 baud, 8 data bits, 1 stop bit, no parity
United Kingdom: 01635 551422
Up to 9,600 baud, 8 data bits, 1 stop bit, no parity
France: 01 48 65 15 59
Up to 9,600 baud, 8 data bits, 1 stop bit, no parity
FTP Support
To access our FTP site, log on to our Internet host, ftp.natinst.com, as anonymousand use
documents are located in the /supportdirectories.
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Fax-on-Demand Support
Fax-on-Demand is a 24-hour information retrieval system containing a library of documents on a wide
range of technical information. You can access Fax-on-Demand from a touch-tone telephone at
512 418 1111.
E-Mail Support (Currently USA Only)
You can submit technical support questions to the applications engineering team through e-mail at the
Internet address listed below. Remember to include your name, address, and phone number so we can
contact you with solutions and suggestions.
Telephone and Fax Support
National Instruments has branch offices all over the world. Use the list below to find the technical
support number for your country. If there is no National Instruments office in your country, contact
the source from which you purchased your software to obtain support.
Country
Telephone
Fax
Australia
Austria
Belgium
Brazil
Canada (Ontario)
Canada (Quebec)
Denmark
Finland
03 9879 5166
0662 45 79 90 0
02 757 00 20
011 288 3336
905 785 0085
514 694 8521
45 76 26 00
09 725 725 11
01 48 14 24 24
089 741 31 30
2645 3186
03 6120092
02 413091
03 5472 2970
02 596 7456
5 520 2635
03 9879 6277
0662 45 79 90 19
02 757 03 11
011 288 8528
905 785 0086
514 694 4399
45 76 26 02
09 725 725 55
01 48 14 24 14
089 714 60 35
2686 8505
France
Germany
Hong Kong
Israel
Italy
Japan
03 6120095
02 41309215
03 5472 2977
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5 520 3282
Korea
Mexico
Netherlands
Norway
Singapore
Spain
Sweden
Switzerland
Taiwan
0348 433466
32 84 84 00
2265886
91 640 0085
08 730 49 70
056 200 51 51
02 377 1200
01635 523545
512 795 8248
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2265887
91 640 0533
08 730 43 70
056 200 51 55
02 737 4644
01635 523154
512 794 5678
United Kingdom
United States
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Technical Support Form
Photocopy this form and update it each time you make changes to your software or hardware, and use
the completed copy of this form as a reference for your current configuration. Completing this form
accurately before contacting National Instruments for technical support helps our applications
engineers answer your questions more efficiently.
If you are using any National Instruments hardware or software products related to this problem,
include the configuration forms from their user manuals. Include additional pages if necessary.
Name __________________________________________________________________________
Company _______________________________________________________________________
Address ________________________________________________________________________
_______________________________________________________________________________
Fax ( ___ ) ________________Phone ( ___ ) __________________________________________
Computer brand____________ Model ___________________Processor_____________________
Operating system (include version number) ____________________________________________
Clock speed ______MHz RAM _____MB
Display adapter __________________________
Mouse ___yes ___no Other adapters installed_______________________________________
Hard disk capacity _____MB Brand_________________________________________________
Instruments used _________________________________________________________________
_______________________________________________________________________________
National Instruments hardware product model _____________ Revision ____________________
Configuration ___________________________________________________________________
National Instruments software product ___________________ Version _____________________
Configuration ___________________________________________________________________
The problem is: __________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
List any error messages: ___________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
The following steps reproduce the problem: ___________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
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LabWindows/CVI Hardware and Software
Configuration Form
Record the settings and revisions of your hardware and software on the line to the right of each item.
Complete a new copy of this form each time you revise your software or hardware configuration, and
use this form as a reference for your current configuration. Completing this form accurately before
contacting National Instruments for technical support helps our applications engineers answer your
questions more efficiently.
National Instruments Products
Hardware revision _______________________________________________________________
Interrupt level of hardware _________________________________________________________
DMA channels of hardware ________________________________________________________
Base I/O address of hardware _______________________________________________________
Programming choice _____________________________________________________________
National Instruments software ______________________________________________________
Other boards in system ____________________________________________________________
Base I/O address of other boards ____________________________________________________
DMA channels of other boards _____________________________________________________
Interrupt level of other boards ______________________________________________________
Other Products
Computer make and model ________________________________________________________
Microprocessor __________________________________________________________________
Clock frequency or speed __________________________________________________________
Type of video board installed _______________________________________________________
Operating system version __________________________________________________________
Operating system mode ___________________________________________________________
Programming language ___________________________________________________________
Programming language version _____________________________________________________
Other boards in system ____________________________________________________________
Base I/O address of other boards ____________________________________________________
DMA channels of other boards _____________________________________________________
Interrupt level of other boards ______________________________________________________
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Documentation Comment Form
National Instruments encourages you to comment on the documentation supplied with our products.
This information helps us provide quality products to meet your needs.
Title:
LabWindows/CVI Programmer Reference Manual
Edition Date: February 1998
Part Number: 320685D-01
Please comment on the completeness, clarity, and organization of the manual.
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
If you find errors in the manual, please record the page numbers and describe the errors.
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
Thank you for your help.
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Title __________________________________________________________________________
Company _______________________________________________________________________
Address ________________________________________________________________________
_______________________________________________________________________________
E-Mail Address __________________________________________________________________
Phone ( ___ ) __________________________ Fax ( ___ ) _______________________________
Mail to: Technical Publications
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Fax to: Technical Publications
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Glossary
Prefix
m-
Meaning
milli-
Value
10–3
10–6
10–9
µ-
micro-
nano-
n-
A
active window
The window user input affects at a given moment. The title of an
active window is highlighted.
API
Application Programming Interface. A set of functions exported by
a library.
Array Display
auto-exclusion
A mechanism for viewing and editing numeric arrays.
A mechanism that prevents pre-existing lines from executing in the
Interactive Execution window.
B
binary control
A function panel control that resembles a physical on/off switch
and can produce one of two values depending upon the position of
the switch.
breakpoint
An interruption in the execution of a program.
Breakpoint
A function that interrupts the execution of a program.
A specific command that interrupts the execution of a program.
Breakpoint command
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Glossary
C
cdecl
A function calling convention in which function calls pass arguments
from right to left, and the caller restores the stack position after
the call.
check box
A dialog box item that allows you to toggle between two possible
options.
clipboard
A temporary storage area LabWindows/CVI uses to hold text that is
cut, copied, or deleted from a work area.
control
An input and output device that appears on a function panel for
specifying function parameters and displaying function results.
cursor
The flashing rectangle that shows where you can enter text on the
screen.
cursor location indicator
An element of the LabWindows/CVI screen that specifies the row
and column position of the cursor in the window.
D
default command
The action that takes place when you press <Enter> and did not
specifically select a command. A double outline indicates default
command buttons in dialog boxes.
dialog box
DLL
A prompt mechanism in which you specify additional information
necessary to complete a command.
Dynamic Link Library. A file that contains a collection of functions
that multiple applications (.exefiles) can use.
E
entry mode indicator
An element of the LabWindows/CVI screen that indicates the current
text entry mode as either insert or overwrite.
excluded code
Code that LabWindows/CVI ignores during compilation and
execution. LabWindows/CVI displays excluded lines of code in a
different color than included lines of code.
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Glossary
F
.fpfile
A file that contains information about the function tree and function
panels of an instrument module.
function panel
A screen-oriented user interface to the LabWindows/CVI libraries in
which you can interactively execute library functions and generate
code for inclusion in a program.
Function Panel Editor window The window in which you build a function panel. The
LabWindows/CVI Instrument Driver Developers Guide.
function panel window
function tree
The window in which you can use function panels.
The hierarchical structure in which the functions in a library or an
instrument driver are grouped. The function tree simplifies access to
a library or instrument driver by presenting functions organized
according to the operation they perform, as opposed to a single linear
listing of all available functions.
Function Tree Editor window
The window in which you build the skeleton of a function panel file.
It is described in the LabWindows/CVI Instrument Driver
Developers Guide.
G
Generated Code box
A small box located at the bottom of the function panel screen that
displays the function call code that corresponds to the current state
of the function panel controls.
global control
A function panel control that displays the contents of global variables
in a library function. Global controls allow you to monitor global
variables in a function that the function does not specifically return
as results by the function. These are read-only controls that cannot be
altered by the user, and do not contribute a parameter to the generated
code.
glue code
Special code that provides the interface between 32-bit
LabWindows/CVI applications and 16-bit DLLs.
H
hex
Hexadecimal.
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Glossary
highlight
The way in which input focus is displayed on a LabWindows/CVI
screen; to move the input focus onto an item.
I
immediate action command
A menu bar item that has no menu items associated with it and causes
a command to execute immediately when you select it. An
immediate action command is suffixed with an exclamation point (!).
input control
input focus
A function panel control that accepts a value you type in from the
keyboard. An input control can have a default value associated with
it. This value appears in the control when the panel is first displayed.
Displayed on the screen as a highlight on an item, signifying that the
item is active. User input affects the item in the dialog box that has
the input focus.
instrument driver
A set of high-level functions for controlling an instrument. It
encapsulates many low-level operations, such as data formatting and
GPIB, RS-232, and VXI communication, into intuitive, high-level
functions. An instrument driver can pertain to one particular
instrument or to a group of related instruments. An instrument driver
consists of a program and a set of function panels. The program
contains the code for the high-level functions. Associated with the
instrument program is an include file that declares the high-level
functions you can call, the global variables you can access, and the
defined constants you can use.
Interactive Execution window A LabWindows/CVI work area in which you can execute sections of
code without creating an entire program.
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Glossary
L
list box
A dialog box item that displays a list of possible choices.
lvalue
A C expression that refers to an object that can be examined and
modified. The name lvalue comes from the fact that only lvalues may
appear on the left side of an assignment. Examples of lvalues are
variables, parameters, array element references such as a[i],
structelement references such as s->nameor s.name, and
pointer dereferences such as *ptr. Expressions that are not lvalues
are called rvalues.
M
MB
Megabytes of memory.
menu
An area accessible from the command bar that displays a subset of
the possible command choices.
O
output control
A function panel control that displays a value that the function you
execute generates. An output control parameter must be a string, an
array, or a reference parameter of type integer, long, single-precision,
or double-precision.
ordinal number
A numeric value that corresponds to a function within a DLL. The
linker that creates the DLL arbitrarily defines it, or it may be
specified in the .deffile when the DLL is created.
P
PASCAL
A Windows 3.1 function calling convention in which function
arguments are passed left to right, and the function restores the stack
pointer before it returns.
Project window
A window that contains a list of files your application uses.
prompt command
A command that requires additional information before it can be
executed; a prompt command appears on a pull-down menu suffixed
with an ellipsis (. . .).
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Glossary
R
return value control
A function panel control that displays a value returned from a
function as a return value rather than as a formal parameter.
ring control
A function panel control that represents a range of values much like
the slide control, but displays only a single item in a list, rather than
displaying the whole list at once as the slide control does. Each item
has a different value associated with it. This value is placed in the
function call.
rvalue
Any C expression that is not an lvalue. Examples of rvalues are array
names, functions, function calls such as f(), assignment expressions
such as x = eand cast expressions such as (AnyType)e.
S
SDK
Windows Software Development Kit. An API in the Windows
operating system.
scroll bars
Areas along the bottom and right sides of a window that show your
relative position in the file. You can use scroll bars can be used to
move about in the window.
scrollable text box
select
A dialog box item that displays text in a scrollable display.
To choose the item that the next executed action affects by moving
the input focus (highlight) to a particular item or area.
shortcut key command
slide control
A combination of keystrokes that provide a means of executing a
command without accessing a menu in the command bar.
A function panel control that resembles a physical slide switch. A
slide control is a means for selecting one item from a list of options;
it inserts a value in a function call that depends upon the position of
the cross-bar on the switch.
slider
The cross-bar on the slide control that determines the value placed in
the function call.
Source window
A LabWindows/CVI work area where you edit and execute
programs.
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Glossary
Standard Input/Output
window
A LabWindows/CVI work area in which textual output to and input
from the user take place.
standard libraries
The LabWindows/CVI User Interface, Analysis, Data Formatting
and I/O, GPIB, GPIB-488.2, DDE, TCP, RS-232, Utility, and
C system libraries.
stdcall
A Windows 95/NT calling convention in which function calls pass
arguments from right to left, and the function restores the stack
pointer before it returns.
String Display window
A window for viewing and editing string variables and arrays.
T
text box
A dialog box item in which you enter text from the keyboard or
view text.
U
User Interface Editor window The window in which you build pull-down menus, dialog boxes,
panels, and controls and save them to a User Interface Resource
(.uir) file. The LabWindows/CVI User Interface Reference Manual
describes it.
V
Variables window
A window that shows the values of the variables that are currently
active.
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Glossary
W
Watch window
A window that shows the values of selected variables and
expressions that are currently active.
window
A working area that supports specific tasks related to developing and
executing programs.
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Index
Special Characters/Numbers
A
#line preprocessor directive, 1-2
_cdecl calling convention qualifier, 1-2
__cdecl calling convention qualifier, 1-2
__declspec(dllexport) qualifier, 1-3, 3-22
__declspec(dllimport) qualifier, 1-3
_export qualifier, 1-3
.a files, using with standalone executables, 7-9
ActiveX Automation Library, 9-6
Add Files to DLL button, 7-15
Add Files to Executable button, 7-15
Advanced Analysis Library, 9-3
Analysis Library, 9-3
__export qualifier, 1-3, 3-22
_import qualifier, 1-3
__import qualifier, 1-3
ANSI C Library
include files, for Windows 95/NT, 3-10
status reporting by, 9-7
_NI_mswin_ macro, 6-1
Sun Solaris libraries
_NI_mswin16_ macro, 6-1
incompatibilities with
LabWindows/CVI, 5-10 to 5-11
non-ANSI behavior, 5-4
_NI_mswin32_ macro, 6-1
_NI_sparc_ macro, 6-1
Solaris 1 implementation, 5-8 to 5-9
static and shared versions, 5-3
ANSI C specifications
_NI_unix_ macro, 6-1
_stdcall calling convention qualifier, 1-2
__stdcall calling convention qualifier
creating static libraries (note), 3-25
creating static objects (note), 3-26
declaring functions for export, 3-21 to 3-22
purpose and use, 1-3
multiplatform application portability, 6-2
non-ANSI LabWindows/CVI compiler
keywords, 1-2
using low-level I/O functions, 1-5
array indexing errors. See pointer protection
errors.
16-bit source code, converting to 32-bit source
code, 1-6 to 1-7
array passing in glue code, 4-9 to 4-11
asynchronous callbacks, compiled modules
using, 2-7
asynchronous DLL functions, 4-11 to 4-12
asynchronous signal handling, UNIX, 5-7 to 5-8
16-bit Windows DLLs. See Windows
16-bit DLLs.
32-bit Borland or Symantec compiled modules
under Windows, 4-2 to 4-3
32-bit source code
converting 16-bit source code to 32-bit
source code, 1-6 to 1-7
DLL calling directly back into 32-bit code,
4-12 to 4-15
32-bit Watcom compiled modules under
Windows 3.1, 4-1 to 4-2
32-bit Windows DLLs. See Windows
32-bit DLLs.
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Index
C library issues, 1-5
C++ style comment markers, 1-4
callback functions
B
bit fields, Windows 32-bit DLLs, 3-6
Borland C/C++
compiled modules using asynchronous
callbacks, 2-7
direct callback by DLLs, 4-12 to 4-15
notification of run state changes in
compiled modules, 2-4 to 2-5
using in DLLs, 2-6 to 2-7
Borland or Symantec 32-bit compiled
modules under Windows, 4-2 to 4-3
Builder not supported by
LabWindows/CVI object or static
library files, 3-17
creating 16-bit Windows DLLs, 4-22
creating object and library files, 3-18
default library directives, 3-16
static versus dynamic C libraries, 3-17
turning off incremental linker, 3-17
Break on Library Errors option, 1-12,
7-19, 9-1
callback references, resolving
(Windows 95/NT)
from modules loaded at run-time, 3-12
references to non-LabWindows/CVI
symbols, 3-12 to 3-13
run-time module
references to symbolsnotexported
from DLL, 3-13
buffer retention by DLL glue code,
4-11 to 4-12
from .uir files, 3-10 to 3-12
linking to callback functions not
exported from DLL, 3-11 to 3-12
calling conventions (Windows 95/NT)
for exported functions, 3-21 to 3-22
using qualifiers, 1-2 to 1-3
casting. See pointer casting.
cdecl calling convention, 1-2
_cdecl calling convention qualifier, 1-2
__cdecl calling convention qualifier, 1-3
Check Disk Dates Before Each Run
option, 4-4
Build menu
Create Distribution Kit command,
7-1, 7-9
External Compiler Support command,
3-11, 3-13
Target command, 3-20, 3-21, 3-25
building platform-independent applications.
See multiplatform applications, building.
bulletin board support, B-1
C
CloseCVIRTE function, 3-14 to 3-15
code. See source files.
.c files. See source files.
C language extensions
colors, multiplatform application
considerations, 6-3
calling conventions (Windows 95/NT),
1-2 to 1-3
comment markers, C++ style, 1-4
compiled modules. See loadable compiled
modules.
compiler. See also compiler options.
C library issues, 1-5
C++-style comment markers, 1-4
duplicate typedefs, 1-4
import and export qualifiers, 1-3 to 1-4
non-ANSI C standard keywords, 1-2
program entry points (Windows), 1-5
structure packing pragma (Windows),
1-4 to 1-5
using low-level I/O functions, 1-5
compiler defines, 1-2
compiler limits (table), 1-1
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Index
data types
allowable data types (table), 1-6
Create Dynamic Link Library command,
3-24, 7-18
Create Object File command, Options
menu, 3-26
converting 16-bit code to 32-bit
code, 1-6 to 1-7
Create Standalone Executable File command,
3-20, 7-16
Create Static Library command, 3-21, 3-26
creating
debugging levels, 1-8
error messages, A-1 to A-46
limits (table), 1-1
non-ANSI C keywords, 1-2
overview, 1-1
user protection errors
loadable compiled modules. See loadable
compiled modules.
platform-independent applications. See
multiplatform applications, building.
standalone executables. See standalone
executables, creating and distributing.
Windows DLLs. See Windows 16-bit
DLLs; Windows 32-bit DLLs.
general protection errors, 1-11
library protection errors, 1-11 to 1-12
memory corruption (fatal), 1-11
memory deallocation
(non-fatal), 1-11
pointer arithmetic (non-fatal),
1-8 to 1-9
pointer assignment (non-fatal), 1-9
pointer casting (non-fatal), 1-10
pointer comparison (non-fatal), 1-10
pointer dereference errors (fatal),
1-9 to 1-10
customer communication, xvi, B-1 to B-2
cvidir configuration option
(Windows 95/NT), 7-7
CVIRTEHasBeenDetached function, 3-3
cvirtx configuration option (Windows 3.1), 7-6
pointer subtraction (non-fatal), 1-10
Compiler Defines command, Options menu,
1-2, 3-27
D
Data Acquisition Library, 9-4
data types
compiler options
allowable data types for compiler
(table), 1-6
compiled object modules
Borland C 4.x, 4-3
converting 16-bit source code to 32-bit
source code, 1-6 to 1-7
DDE Library, 9-6
Symantec C++ 6.0, 4-3
Watcom, 4-2
setting, 1-2
Compiler Options command, Options
menu, 1-2
compiler/linker issues. See specific operating
system, e.g., UNIX operating system.
configuring Run-time Engine. See Run-time
Engine, configuring.
converting 16-bit source code to 32-bit source
code, 1-6 to 1-7
debugging levels
Extended, 1-8
setting, 1-8
Standard, 1-8
__declspec(dllexport) qualifier, 1-3, 3-22
__declspec(dllimport) qualifier, 1-3
distributing libraries, 8-1 to 8-3
adding to user’s Library menu, 8-1 to 8-2
specifying library dependencies,
8-2 to 8-3
Create Distribution Kit command, Build
menu, 7-1, 7-9
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distributing standalone executables. See
standalone executables, creating and
distributing.
status codes
checking function call status
codes, 9-1
DLLEXPORT macro, 1-4, 3-22 to 3-23
DLLIMPORT macro, 1-4
returned by LabWindows/CVI
functions, 9-2 to 9-3
DllMain function, in DLLs, 3-3
DLLs. See Windows 16-bit DLLs; Windows
32-bit DLLs.
DLLSTDCALL macro, 3-22, 3-24
dlopen function, Sun Solaris, 5-2
documentation
status reporting by libraries and
instrument drivers, 9-3 to 9-7
errors. See also user protection errors.
compiler-related error messages,
A-1 to A-46
events, multiplatform application
considerations, 6-3
executable file, required for standalone
executables, 7-8
conventions used in manual, xiv-xv
organization of manual, xiii-xiv
related documentation, xv
executables, creating and distributing. See
standalone executables, creating and
distributing.
doubles, returning, 3-7
DSTRules option, 7-7
duplicate typedefs, 1-4
dynamic memory protection, 1-15
dynamic memory protection errors
memory corruption (fatal), 1-11
memory deallocation (non-fatal), 1-11
export qualifiers
_export, 1-3
__export, 1-3, 3-22
exporting DLL functions and
variables, 3-22
purpose and use, 1-3 to 1-4
External Compiler Support command, Build
menu, 3-11, 3-13
external modules. See also loadable compiled
modules.
E
Easy I/O for DAQ Library, 9-4
Edit menu
Function Tree Editor, 8-2
Source, Interactive Execution, and
Standard Input/Output windows, 3-3
electronic support services, B-1 to B-2
e-mail support, B-2
enum sizes, Windows 32-bit DLLs, 3-7
error checking, 9-1 to 9-7
Break on Library Errors option, 1-12,
7-19, 9-1
definition, 2-4
forcing referenced modules into
executable or DLL, 7-15
multiplatform application
considerations, 6-3
under UNIX
compiling with external compilers,
5-6 to 5-7
restrictions, 5-6
overview, 9-1
standalone executables, 7-19
using loadable compiled module as, 2-4
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F
G
fax and telephone support numbers, B-2
Fax-on-Demand support, B-1
files for running standalone executables
accessing UIR, image, and panel state
files, 7-12
general protection errors, 1-11
Generate DLL Glue Code command, Options
menu, 4-8, 4-9
Generate DLL Glue Object command,
Options menu, 7-17
Generate DLL Import Library command,
Options menu, 3-4, 3-5
Generate DLL Import Source command,
Options menu, 3-21
Generate Windows Help command, Options
menu, 3-25
GetCVIWindowHandle function, 4-21
glue code. See Windows 16-bit DLLs.
GNU C Compiler, 5-3
DLL files
Windows 3.1, 7-13 to 7-14
Windows 95/NT, 7-13
loading files using LoadExternalModule,
7-14 to 7-18
DLL files and DLL path files
(Windows 3.1), 7-17 to 7-18
DLL files (Windows 95/NT), 7-17
files in project, 7-15 to 7-16
forcing referenced modules into
executable or DLL, 7-15
library files not in project, 7-16
object files not in project, 7-16
other types of files, 7-19
GPIB/GPIB 488.2 Library, 9-4 to 9-5
graphical user interface (GUI), multiplatform
application considerations, 6-3
H
source files, 7-18
hardware interrupts under
Windows 95/NT, 3-29
location of files on target machine,
7-9 to 7-19
relative pathnames for accessing
files, 7-19
hot keys, multiplatform application
considerations, 6-3
required files, 7-8 to 7-9
floats, returning, 3-7
fonts
I
image files
multiplatform application
considerations, 6-3
Windows 95/NT files for standalone
executables, 7-11
accessing from standalone
executables, 7-12
multiplatform application
considerations, 6-3
Formatting and I/O Library, 9-6 to 9-7
forward <delete> key, multiplatform
application considerations, 6-3
.FP Auto-Load List command, Edit menu, 8-2
FTP support, B-1
using with standalone executables, 7-9
import libraries (Windows 95/NT)
automatic loading of SDK import
libraries, 3-27 to 3-28
compatibility with external compilers, 3-5
customizing DLL import libraries,
3-20 to 3-21
functions exported by ordinal value only, 4-20
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generating DLL import library, 3-4
link errors when using DLL import
libraries, 3-2
K
keywords, non-ANSI LabWindows/CVI, 1-2
import qualifiers
_import, 1-3
__import, 1-3
L
LabWindows/CVI compiler. See compiler.
LabWindows/CVI Run-time Engine. See
Run-time Engine.
.lib files. See library files.
libraries
marking imported symbols in include file,
3-23 to 3-24
purpose and use, 1-2 to 1-3
include files
ANSI C library and LabWindows/CVI
libraries, 3-10
generating glue code, 4-9
Windows 32-bit DLLs
exporting DLL functions and
variables, 3-22
C library issues, 1-5
creating static libraries, 3-25
distributing, 8-1 to 8-3
adding to user’s Library menu,
8-1 to 8-2
specifying library dependencies,
8-2 to 8-3
marking imported symbols in include
file, 3-23 to 3-24
Windows SDK functions, 3-26 to 3-27
include paths, setting up for
LabWindows/CVI, ANSI C, and SDK
libraries, 3-28 to 3-29
Include Paths command, Options menu,
1-17, 3-28
InitCVIRTE, calling
loading library files for standalone
executables, 7-16
portability issues for multiplatform
applications, 6-1 to 6-2
using loadable compiled modules as user
libraries, 2-3
Windows 95/NT compiler issues
calling InitCVIRTE and
UNIX executables, 5-4 to 5-5
Windows 95/NT executables,
3-14 to 3-15
CloseCVIRTE, 3-14 to 3-15
include files for ANSI C library and
LabWindows/CVI libraries, 3-10
multithreading and
LabWindows/CVI libraries, 3-8
resolving callback references from
.uir files, 3-10 to 3-12
Insert Constructs command, Edit menu, 3-3
Instrument Directories command, Options
menu, 8-2
instrument drivers
definition, 2-2
status reporting, 9-7
resolving references from modules
loaded at run-time, 3-12
using loadable compiled modules as
program files, 2-2
Instrument menu, 2-3, 7-15
interrupts under Windows 95/NT, 3-29
IVI Library, 9-5
standard input/output windows, 3-10
using LabWindows/CVI libraries in
external compilers, 3-9 to 3-15
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library files
compatibility with external compilers
32-bit Borland or Symantec compiled
modules under Windows, 4-2 to 4-3
32-bit Watcom compiled modules under
Windows 3.1, 4-1 to 4-2
advantages and disadvantages, 2-2
external modules, 2-4
instrument driver program files,
2-2 to 2-3
modules compiled by
(Windows 95/NT), 3-5
creating in external compilers for use in
LabWindows/CVI, 3-18 to 3-19
loading with LoadExternalModule, 7-16
using with standalone executables, 7-9
library function user protection errors, 1-16
disabling, 1-13 to 1-14
LabWindows/CVI, 4-1
multiplatform application
considerations, 6-3
notification of run state changes,
2-4 to 2-6
Library menu
appearance of user libraries on, 2-3
installing user libraries, 2-3, 8-1 to 8-2
linking modules with external
modules, 7-15
examples of program state changes,
2-5 to 2-6
Library Options command, Project Options
menu, 2-3, 8-1
modules using asynchronous
callbacks, 2-4
overview, 2-1
project list, 2-3 to 2-4
requirements, 2-1
UNIX compiler/linker issues, 5-6 to 5-7
compiling, 5-6 to 5-7
restrictions, 5-6
user libraries, 2-3
library protection errors, 1-11 to 1-12
disabling
for functions, 1-13 to 1-14
at run-time, 1-12
errors involving library protection,
1-11 to 1-12
loadable compiled modules
16-bit Windows DLLs
creating
Windows messages passed from
DLLs, 4-21
with Borland C++, 4-22
with Microsoft Visual C++ 1.5,
4-21 to 4-22
GetCVIWindowHandle
function, 4-21
RegisterWinMsgCallback
function, 4-21
UnRegisterWinMsgCallback
function, 4-21
glue code
DLLs unable to use glue code
generated at load time,
4-8 to 4-20
DLLs using glue code generated
at load time, 4-8
requirements, 4-7
LoadExternalModule rules, 7-14 to 7-18
DLL files and DLL path files
(Windows 3.1), 7-17 to 7-18
DLL files (Windows 95/NT), 3-2, 7-17
files listed in project, 7-15 to 7-16
forcing modules into executable or
DLL, 7-15
helpful LabWindows/CVI
options, 4-4
overview, 4-3 to 4-4
rules and restrictions, 4-5 to 4-7
search precedence, 4-23 to 4-24
library files not in project, 7-16
object files not in project, 7-16
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other types of files, 7-19
source files, 7-18
multithreading
creating multiple threads with Windows
SDK functions, 3-27
using LabWindows/CVI libraries, 3-8
locking process segments into memory using
plock(), 5-7
long doubles, Windows 32-bit DLLs, 3-7
low-level I/O functions, using, 1-5
low-level support driver, used by Run-time
Engine, 7-10 to 7-11
N
_NI_mswin_ macro, 6-1
_NI_mswin16_ macro, 6-1
_NI_mswin32_ macro
M
multiplatform programming, 6-1
required for external compilers, 3-8
_NI_sparc_ macro, 6-1
macros, predefined, 6-1
manual. See documentation.
math coprocessor software emulation for
Windows 3.1, 7-2
_NI_unix_ macro, 6-1
memory protection errors
O
memory corruption (fatal), 1-11
memory deallocation (non-fatal), 1-11
message file for Run-time Engine
translating, 7-5
.o files
loading with LoadExternalModule, 7-14
using with standalone executables, 7-9
object files
Windows 95/NT, 7-11
messages passed from DLLs. See Windows
messages passed from DLLs.
Microsoft Visual Basic, automatic inclusion of
Type Library resource for, 3-24 to 3-25
Microsoft Visual C/C++
creating 16-bit Windows DLLs,
4-21 to 4-22
creating object and library files, 3-18
default library directives, 3-16
minimum system requirements for standalone
executables, 7-1 to 7-2
compatibility with external compilers
(Windows 95/NT), 3-5
creating
in external compilers for use in
LabWindows/CVI, 3-18 to 3-19
in LabWindows/CVI, 3-26
loading with LoadExternalModule, 7-14
using with standalone executables, 7-9
Options menu
Function Tree Editor, Generate Windows
Help command, 3-25
missing return value (non-fatal) error, 1-11
modini program (caution), 8-2, 8-3
modreg program (caution), 8-2, 8-3
multiplatform applications, building
externally compiled module issues, 6-3
library portability issues, 6-1 to 6-2
predefined macros, 6-1
Project window
Compiler Defines command,
1-2, 3-27
Compiler Options command, 1-2
Include Paths command, 1-17, 3-28
Instrument Directories
command, 8-2
Run Options command, 1-8,
1-12, 1-16
programming guidelines, 6-1 to 6-3
user interface guidelines, 6-3
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Source, Interactive Execution, and
Standard Input/Output windows
Create Object File command, 3-26
Generate DLL Glue Code command,
4-8, 4-9
pointers
DLLs passing pointers that point to other
pointers, 4-18 to 4-20
returned by DLLs, 4-15 to 4-17
pragmas
Generate DLL Glue Object
command, 7-17
disabling or enabling library protection
errors, 1-13 to 1-14
Generate DLL Import Library
command, 3-4, 3-5
structure packing (Windows),
1-4 to 1-5, 3-6
Generate DLL Import Source
command, 3-21
predefined macros, 6-1
printf function
ordinal value for exporting functions, 4-20
LabWindows/CVI implementation, 5-4
using with external compiler, 3-10
process segments, locking into memory using
plock(), 5-7
program entry points (Windows), 1-5
Project window, Run Options menu, 4-4
projects. See also source files.
loadable compiled modules in project list,
2-3 to 2-4
P
pack pragma (Windows), 1-4 to 1-5, 3-6
panel state files
accessing from standalone
executables, 7-12
required for standalone executables, 7-9
pascal, Pascal, and _pascal keywords, 1-2
Pascal DLL functions, 4-8, 4-9
path files. See .pth files.
loading project files with
LoadExternalModule, 7-15 to 7-16
.pth files
PCX files, multiplatform application
considerations, 6-3
loading with LoadExternalModule,
7-17 to 7-18
platform-independent applications, building.
See multiplatform applications, building.
plock function, UNIX, 5-7
not supported for Windows 95/NT, 3-2
using with standalone executables, 7-9
pointer casting, 1-14
Q
pointer protection errors, 1-8 to 1-10
disabling for individual pointers,
1-12 to 1-13
Q387 coprocessor emulation software
(Quickware), 7-2
dynamic memory protection errors, 1-11
pointer arithmetic (non-fatal), 1-8 to 1-9
pointer assignment (non-fatal), 1-9
pointer casting (non-fatal), 1-10
pointer comparison (non-fatal), 1-10
pointer dereference errors (fatal),
1-9 to 1-10
R
references, resolving. See callback references,
resolving (Windows 95/NT).
RegisterWinMsgCallback function, 4-21
Reload DLLs Before Each Run option, 4-4
resolving references. See callback references,
resolving.
pointer subtraction (non-fatal), 1-10
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resource files (Windows 95/NT), for
standalone executables, 7-11
return values, missing (non-fatal) error, 1-11
RS-232 Library, 9-5
system requirements
Windows 3.1, 7-2
Windows 95/NT, 7-1 to 7-2
translating message file, 7-5
Run Options command, Options menu
Break on library errors option, 1-12, 7-19
setting debugging levels, 1-8
setting maximum stack size, 1-16
Run Options menu, Project window, 4-4
run state change notification for compiled
modules
S
scanf function
LabWindows/CVI implementation, 5-4
using with external compiler, 3-10
SDK functions. See Windows SDK functions.
search precedence of Windows DLLs,
4-23 to 4-24
shared libraries, under UNIX, 5-2
shortcut keys, multiplatform application
considerations, 6-3
asynchronous callbacks, 2-4
examples of program state changes,
2-5 to 2-6
including in DLLs, 3-2 to 3-3
prototype for callback, 2-4
requirements, 2-4
SIGBUS signal, 5-7
SIGFPE signal, 5-7
unavailable
SIGILL signal, 5-7
SIGINT signal, 5-7
SIGPIPE signal, 5-7
SIGPOLL (SIGIO) signal, 5-7
SIGQUIT signal, 5-7
for executables under UNIX, 5-5
for external compilers under
Windows 95/NT, 3-13 to 3-14
Run-time Engine. See also standalone
executables, creating and distributing.
configuring, 7-5 to 7-7
SIGSEGV signal, 5-7
cvidir option, 7-7
SIGTERM signal, 5-7
cvirtx option, 7-6
DSTRules, 7-7
Solaris. See Sun Solaris.
source files
option descriptions, 7-6
converting 16-bit source code to 32-bit
source code, 1-6 to 1-7
loading with LoadExternalModule, 7-18
preparing for use in Windows 32-bit DLL,
3-21 to 3-24
setting configuration options, 7-6
Solaris 1 patches required, 7-5 to 7-6
UNIX options, 7-7
useDefaultTimer, 7-7
calling conventions for exported
functions, 3-21 to 3-22
files required for running executable
programs, 7-8 to 7-9
exporting DLL functions and
variables, 3-22
location and type of files, 7-9 to 7-11
Windows 3.1, 7-11 to 7-12
Windows 95/NT, 7-10 to 7-11
overview, 7-1
export qualifier method,
3-22 to 3-23
include file method, 3-22
shared library capability, 5-2
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marking imported symbols in include
file distributed with DLL,
3-23 to 3-24
math coprocessor software emulation for
Windows 3.1, 7-2
relative pathnames for accessing
files, 7-19
recommendations, 3-24
stack overflow error (fatal), 1-11
translating message file, 7-5
UNIX compiler/linker issues, 5-3 to 5-5
compatible compilers, 5-3
InitCVIRTE called by main function,
5-4 to 5-5
stack size, 1-16 to 1-17
standalone executables, creating and
distributing
accessing UIR, image, and panel state
files, 7-12
configuring Run-time Engine, 7-5 to 7-7
distributing
non-ANSI behavior of Sun Solaris 1
ANSI C library, 5-4
printf and scanf under
LabWindows/CVI, 5-4
Solaris 1, 7-4 to 7-5
run state change callbacks not
available, 5-5
Solaris 2, 7-3 to 7-4
UNIX, 7-2 to 7-5
static and shared versions of ANSI C
and other Sun libraries, 5-3 to 5-4
Windows 3.1 system requirements,
7-1 to 7-2
Windows 3.1, 7-2
Windows 95/NT, 7-1 to 7-2
error checking, 7-19
loading files using LoadExternalModule,
7-14 to 7-18
Windows 95/NT, 3-20
necessary files, 7-9
DLL files and DLL path files
(Windows 3.1), 7-17 to 7-18
DLL files for Windows 95/NT, 7-17
library files, 7-16
system requirements, 7-1 to 7-2
standard input/output windows,
LabWindows/CVI, 3-10
state change notification for compiled
modules. See run state change notification
for compiled modules.
state files. See panel state files.
static libraries, creating, 3-25
status codes
object modules, 7-16
source files, 7-18
location of files on target machine,
7-9 to 7-19
DLL files
Windows 3.1, 7-10 to 7-11
Windows 95/NT, 7-10
loading files using
LoadExternalModule,
7-14 to 7-18
checking function call status codes, 9-1
definition (note), 9-2
returned by LabWindows/CVI functions,
9-2 to 9-3
status reporting by libraries and instrument
drivers, 9-3 to 9-7
Run-time Engine under
Windows 95/NT, 7-10 to 7-11
UIR, image, and panel state
files, 7-12
ActiveX Automation Library, 9-6
Advanced Analysis Library, 9-3
Analysis Library, 9-3
ANSI C Library, 9-7
Data Acquisition Library, 9-4
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DDE Library, 9-6
Sun Solaris
distribution of standalone executables
Easy I/O for DAQ Library, 9-4
Formatting and I/O Library, 9-6 to 9-7
GPIB/GPIB 488.2 Library, 9-4 to 9-5
IVI Library, 9-5
LabWindows/CVI Run-Time Engine
files, 7-12
Solaris 1, 7-4 to 7-5
Solaris 1 patches required, 7-5 to 7-6
Solaris 2, 7-3 to 7-4
LabWindows/CVI instrument drivers, 9-7
RS-232 Library, 9-5
incompatibilities with
TCP Library, 9-6
LabWindows/CVI, 5-11
support modules for glue code, 4-9
Symantec C/C++
User Interface Library, 9-3
Utility Library, 9-7
VISA Library, 9-5
creating object and library files, 3-19
default directives, 3-16
VXI Library, 9-4
X Property Library, 9-6
Symantec or Borland 32-bit compiled
modules under Windows, 4-2 to 4-3
_stdcall calling convention qualifier, 1-2
__stdcall calling convention qualifier
creating static libraries (note), 3-25
creating static objects (note), 3-26
declaring functions for export,
3-21 to 3-22
purpose and use, 1-3
structure packing pragmas (Windows),
1-4 to 1-5, 3-6
T
Target command, Build menu, 3-20,
3-21, 3-25
TCP Library, 9-6
technical support, B-1 to B-2
telephone and fax support numbers, B-2
Type Library resource for Visual Basic,
3-24 to 3-25
Sun C Compiler, 5-3
Sun C library. See also UNIX compiler/linker
issues.
typedefs, duplicate, 1-4
ANSI C implementation, 5-8 to 5-9
functions not available, 5-9
incompatibilities with
LabWindows/CVI, 5-10 to 5-11
replacement functions (table), 5-9
calling Sun C library from source
code, 5-1
U
.uir files. See user interface resource
(.uir) files.
unions, 1-16
UNIX C library. See Sun C library.
UNIX compiler/linker issues, 5-1 to 5-11
asynchronous signal handling, 5-7 to 5-8
calling Sun C library functions, 5-1
restrictions, 5-1
restrictions, 5-1
LabWindows/CVI implementation of
printf and scanf, 5-4
non-ANSI behavior, 5-4
static and shared versions, 5-3
using low-level I/O functions, 1-5
creating executables, 5-3 to 5-5
compatible external compilers, 5-3
InitCVIRTE called by main function,
5-4 to 5-5
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non-ANSI behavior of Sun Solaris 1
ANSI C library, 5-4
printf and scanf functions under
LabWindows/CVI, 5-4
User Interface Library, 9-3
user interface resource (.uir) files
accessing from running standalone
executables, 7-12
run state change callbacks not
available, 5-5
multiplatform application
considerations, 6-3
static and shared versions of ANSI C
and Sun libraries, 5-3 to 5-4
externally compiled modules, 5-6 to 5-7
compiling, 5-6 to 5-7
required for running standalone
executables, 7-9
resolving callback references from,
3-10 to 3-12
restrictions, 5-6
linking to callback functions not
exported from DLL, 3-11 to 3-12
user libraries. See also libraries.
incompatibilities, 5-10 to 5-11
between LabWindows/CVI and
ANSI C, 5-10 to 5-11
installing, 2-3
between LabWindows/CVI and Sun
Solaris, 5-11
similarity with instrument driver, 2-3
using loadable compiled modules, 2-3
locking process segments in memory
using plock(), 5-7
shared libraries, 5-2
user protection
dynamic memory, 1-15
library functions, 1-16
pointer casting, 1-14
stack size, 1-16 to 1-17
unions, 1-16
LabWindows/CVI Run-time Engine
as shared library, 5-2
using dlopen, 5-2
Solaris 1 ANSI C Library
implementation, 5-8 to 5-9
functions not found in Sun Solaris 1
libc, 5-9
user protection errors
disabling, 1-12 to 1-14
for individual pointer, 1-12 to 1-13
library errors
for functions, 1-13 to 1-14
at run-time, 1-12
at run-time, 1-12
replacement functions (table), 5-9
UNIX operating system
configuration options for Run-time
Engine, 7-7
distribution of standalone executables,
7-2 to 7-5
error category, 1-8
general protection errors, 1-11
library protection errors, 1-11 to 1-12
memory corruption (fatal), 1-11
memory deallocation (non-fatal), 1-11
pointer arithmetic (non-fatal), 1-8 to 1-9
pointer assignment (non-fatal), 1-9
pointer casting (non-fatal), 1-10
pointer comparison (non-fatal), 1-10
pointer dereference errors (fatal),
1-9 to 1-10
minimum system requirements, 7-5
Solaris 1, 7-4 to 7-5
Solaris 2, 7-3 to 7-4
Unload command, Instruments menu, 2-3
UnRegisterWinMsgCallback function, 4-21
useDefaultTimer option, 7-7
user interface. See graphical user
interface (GUI).
user interface events. See events.
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pointer subtraction (non-fatal), 1-10
severity level, 1-8
Windows 16-bit DLLs
creating
Utility Library, 9-7
with Borland C++, 4-22
with Microsoft Visual C++ 1.5,
4-21 to 4-22
V
DLLs unable to use glue code generated
at load time, 4-8 to 4-20
arrays bigger than 64 K, 4-9 to 4-11
buffer retained after function returns
(asynchronous function),
4-11 to 4-12
va_arg (ap, type), 1-2
VISA Library, 9-5
Visual Basic. See Microsoft Visual Basic.
Visual C/C++. See Microsoft Visual C/C++.
VXI Library, 9-4
direct callbacks into 32-bit code,
4-12 to 4-15
W
functions exported by ordinal value
only, 4-20
Watcom C/C++
loading, 4-8 to 4-9
pointer that points to other pointers,
4-18 to 4-20
returning pointers, 4-15 to 4-17
rules for include file, 4-9
support module required outside of
DLL, 4-9
32-bit compiled modules under
Windows 3.1, 4-1 to 4-2
creating object and library files, 3-19
default directives, 3-16
pull-in references, 3-17
stack based calling convention, 3-15
Watcom WEMU387.386 coprocessor
emulation software, 7-2
DLLs using glue code generated at load
time, 4-8
Windows 3.1
fixing linker error (note), 4-7
helpful LabWindows/CVI options, 4-4
not supported in Windows 95/NT, 3-2
overview, 4-3 to 4-4
compiler/linker issues
16-bit Windows DLLs. See Windows
16-bit DLLs.
32-bit Borland or Symantec
compiled modules, 4-2 to 4-3
32-bit Watcom compiled modules,
4-1 to 4-2
requirements, 4-7
rules and restrictions, 4-5 to 4-7
search precedence, 4-23 to 4-24
for standalone executables
definition, 7-9
modules compiled by
LabWindows/CVI, 4-1
cvirtx option for configuring Run-time
Engine, 7-6
loading with LoadExternalModule,
7-17 to 7-18
distributing standalone executables
math coprocessor software
emulation, 7-2
rules for using, 7-13 to 7-14
unusable in specific situations, 4-8
minimum system requirements, 7-2
structure packing pragmas, 1-4 to 1-5
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Windows 32-bit DLLs
compatibility with external compilers
bit fields, 3-6
releasing resources when DLL
unloads, 3-3 to 3-4
run state change callbacks in DLLs,
3-2 to 3-3
using LoadExternalModule
function, 3-2
choosing compatible compiler, 3-5
enum sizes, 3-7
long doubles, 3-7
for standalone executables
distributing, 7-9
returning floats and doubles, 3-7
returning structures, 3-7
structure packing, 3-6
creating in LabWindows/CVI,
3-20 to 3-25
loading with
LoadExternalModule, 7-17
location, 7-10
rules for using, 7-13
using run state change callbacks,
2-6 to 2-7
automatic inclusion of Type Library
resource for Visual Basic,
3-24 to 3-25
Windows 95/NT
calling conventions for exported
functions, 3-21 to 3-22
customizing import library,
3-20 to 3-21
32-bit DLLS. See Windows 32-bit DLLs.
calling convention qualifiers in function
declarations, 1-2 to 1-3
calling SDK functions in
LabWindows/CVI, 3-26 to 3-28
automatic loading of SDK import
libraries, 3-27 to 3-28
exporting DLL functions and
variables, 3-22
export qualifier method,
3-22 to 3-23
creating multiple threads using
Windows SDK functions, 3-27
SDK include files, 3-26 to 3-27
user interface capabilities, 3-27
compatibility with external compilers,
3-4 to 3-8
include file method, 3-22
marking imported symbols in include
file distributed with DLL,
3-23 to 3-24
preparing source code, 3-21 to 3-24
recommendations, 3-24
DLL import library compatibility with
external compilers, 3-5
loading, 3-1 to 3-4
choosing a compiler, 3-5
DLLs, 3-5
external compiler versions
supported, 3-8
LabWindows/CVI differences,
3-7 to 3-8
16-bit DLLs not supported, 3-2
default unloading/reloading
policy, 3-4
object files, library files, and DLL
import libraries, 3-5
DLL path (.pth) files not
supported, 3-2
required preprocessor definitions, 3-8
compiler/linker issues
DllMain function, 3-3
DLLs for instrument drivers and user
libraries, 3-2
generating import library, 3-4
link errors when using DLL import
libraries, 3-2
calling SDK functions, 3-26 to 3-28
compatibility with external
compilers, 3-4 to 3-8
creating DLLs, 3-20 to 3-25
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creating executables, 3-20
creating object and library files in
external compilers, 3-18 to 3-19
creating object files, 3-26
creating static libraries, 3-25
hardware interrupts, 3-29
LabWindows/CVI libraries in
external compilers, 3-9 to 3-15
loading 32-bit DLLs, 3-1 to 3-4
multithreading, 3-8
LabWindows/CVI libraries in external
compilers, 3-9 to 3-15
calling InitCVIRTE and
CloseCVIRTE, 3-14 to 3-15
include files, 3-10
resolving callback references from
.uir files, 3-10 to 3-12
resolving references from modules
loaded at run-time, 3-12 to 3-13
run state change callbacks
unavailable, 3-13 to 3-14
object and library files in external
compilers, 3-15 to 3-17
standard input/output window, 3-10
Watcom stack based calling
convention, 3-15
setting up include paths, 3-28 to 3-29
creating object and library files in external
compiler, 3-18 to 3-19
multithreading and LabWindows/CVI
libraries, 3-8
Borland C/C++, 3-18
program entry points, 1-5
setting up include paths for
LabWindows/CVI, ANSI C, and SDK
libraries, 3-28 to 3-29
structure packing pragmas, 1-4 to 1-5
using object and library files in external
compiler, 3-15 to 3-17
Microsoft Visual C/C++, 3-18
Symantec C/C++, 3-19
Watcom C/C++, 3-19
creating object files in
LabWindows/CVI, 3-26
creating static libraries in
LabWindows/CVI, 3-25
Borland C++ Builder, 3-17
Borland incremental linker, 3-17
Borland static versus dynamic C
libraries, 3-17
default library directives,
3-15 to 3-16
cvidir option for configuring Run-time
Engine, 7-7
distributing standalone executables
coprocessor not required, 7-2
creating in LabWindows/CVI, 3-20
location of files, 7-10 to 7-11
low-level support driver, 7-10 to 7-11
message, resource, and font
files, 7-11
Borland C/C++, 3-16
Microsoft Visual C/C++, 3-16
Symantec C/C++, 3-16
Watcom C/C++, 3-16
minimum system requirements, 7-1
National Instruments hardware I/O
libraries, 7-11
Watcom pull-in references, 3-17
Windows messages passed from DLLs, 4-21
GetCVIWindowHandle function, 4-21
RegisterWinMsgCallback function, 4-21
UnRegisterWinMsgCallback
function, 4-21
Run-time Library DLLs, 7-10
system requirements, 7-1 to 7-2
hardware interrupts, 3-29
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Index
Windows SDK functions, 3-26 to 3-28
automatic loading of SDK import
libraries, 3-27 to 3-28
calling in LabWindows/CVI, 3-26 to 3-28
creating multiple threads, 3-27
include files, 3-26 to 3-27
setting up include paths for SDK libraries,
3-28 to 3-29
user interface capabilities, 3-27
X
X Property Library, status reporting by, 9-6
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