National Instruments 320685D-01 ユーザーズマニュアル

Chapter 4

Windows 3.1 Compiler/Linker Issues

LabWindows/CVI Programmer Reference Manual

4-18

©

 National Instruments Corporation

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 

ptrs

 to 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 

f

 and 

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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