Slide 15.8: Calling C/C++ functions (cont.)

Slide 15.7: Calling C/C++ functions
Slide 15.9: Calling C/C++ functions (cont.)
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Calling C/C++ Functions (Cont.)

Assembly Language Module
The discussions are based on whether the assembly language module calls procedures from the link library:

Using the ’s link library: If the assembly language module will be calling procedures from the link library, you must add the C qualifier to the directive when declaring external C/C++ functions to be called by the assembly module:
```
   INCLUDE  Irvine32.inc
   askForInteger  PROTO  C
   showInt  PROTO  C,  value: SDWORD, outWidth: DWORD
```
Assembly language procedures called by the C++ program must use also the C qualifier so the assembler will use a naming convention the linker can recognize. For example,
```
   DisplayFactors PROC C 
      ...

   DisplayFactors ENDP
```
Using the directive: If the assembly language code does not call procedures, you can tell the directive to use the C calling convention:
```
   ; (do not INCLUDE Irvine32.inc)
   .586
   .model  flat, C
```
Now you no longer have to add the C qualifier to the and directives:
```
   askForInteger  PROTO
   showInt  PROTO, value: SDWORD, outWidth: DWORD
   DisplayFactors PROC
     ...
   DisplayFactors ENDP
```

“I’m not arguing, I’m just explaining why I’m right.”
― Unknown