Slide 14.9: Calling C/C++ functions (cont.)

Calling C/C++ Functions (Cont.)

Assembly Language Module
The discussions are based on whether the assembly language module calls procedures from the Irvine32 link library:

Using the Irvine32's link library: If the assembly language module will be calling procedures from the Irvine32 link library, you must add the C qualifier to the PROTO 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 .MODEL directive: If the assembly language code does not call Irvine32 procedures, you can tell the .MODEL 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 PROTO and PROC directives:
```
   askForInteger  PROTO
   showInt  PROTO, value: SDWORD, outWidth: DWORD
 
   DisplayFactors PROC
     ...
   DisplayFactors ENDP
```