National Instruments 320685D-01 DLLs That Can Use Glue Code Generated at Load Time , DLLs That Cannot Use Glue Code Generated at Load Time , Loading a DLL That Cannot Use Glue Code Generated at Load Time

Chapter 4 Windows3.1 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 ANSIC 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 f i le that contains glue co de fo r 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 .libfile.

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.