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Chapter 4 Windows 3.1 Compiler/Linker Issues
LabWindows/CVI Programmer Reference Manual 4-8
©
National Instruments Corporation
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
.h file it associates with the DLL when
it loads it.
Any functions declared as
PASCAL, pascal, or _pascal in the DLL should be declared as
PASCAL in the .h file. LabWindows/CVI ignores the PASCAL keyword except when
generating the glue code.
Use only standard ANSI C keywords in the
.h file. (The keyword PASCAL is 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
.h file 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
.fp file, make sure the object
module is in the same directory as the
.fp file.
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
.obj or .lib file 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
.obj or .lib file.
Loading a DLL That Cannot Use Glue Code Generated
at Load Time
If you have a 32-bit Watcom compiled .obj or .lib file that contains glue code for a DLL,
LabWindows/CVI must load the
.obj or .lib file first. For instance, if you want to use
x.dll and x.obj in your program, add x.obj to the project. Do not add x.dll to the
project. The
.obj or .lib file causes LabWindows/CVI to load the .dll.
The
.obj or .lib file must contain the glue code for the DLL. It is the presence of the glue
code that indicates to LabWindows/CVI that a
.dll is associated with the .obj or .lib file.
When LabWindows/CVI loads the
.obj or .lib file and finds that it contains glue code, it
first looks for the
.dll in the same directory as the .obj or .lib file. If it cannot find
the
.dll, LabWindows/CVI looks for it using the standard Windows DLL search algorithm.
00ProRef.book : 06chap04.fm Page 8 Monday, March 9, 1998 3:23 PM