Static Variables Declared in MASM Routines Called from C

• Microsoft Macro Assembler for MS-DOS, versions 5.0, 5.1, 6.0, 6.0a, and 6.0b
• Microsoft Macro Assembler for OS/2, versions 5.0, 5.1, 6.0, 6.0a, and 6.0b

SUMMARY

The programs below demonstrate how a variable declared in a Microsoft Macro Assembler (MASM) subprogram will keep its value between calls from a C main program.

MORE INFORMATION

Link the two programs below with the following command:

   link cmain masmsub,,, /nod llibce;

Sample Code #1

// Filename: CMAIN.C
// Compile options needed: /c /AL

#include <stdio.h>

main () {

   int i ;
   for (i = 1; i < 11; ++i)          // Call the MASM subprogram 10
   {                                 // times, and its return value
      printf ("%d\n", MasmSub()) ;   // will be incremented by 1 each
   }                                 // time.
}

Sample Code #2

; Filename: MASMSUB.ASM ; Assemble options needed: /mx /ml

.MODEL LARGE, C .DATA

   var DW 0        ; This variable will keeps its value between calls.

   INC var
   MOV AX, var     ; Since the function returns an int, C will get the
   RET             ; return value from AX.

        END