Article ID: 103725
Article Last Modified on 7/1/2004
APPLIES TO
- Microsoft C Professional Development System 6.0a
- Microsoft C Professional Development System 6.0a
- Microsoft C/C++ Professional Development System 7.0
- Microsoft Visual C++ 1.0 Professional Edition
- Microsoft Visual C++ 1.5 Professional Edition
- Microsoft Visual C++ 2.0 Professional Edition
- Microsoft Visual C++ 4.0 Standard Edition
- Microsoft Visual C++ 5.0 Enterprise Edition
- Microsoft Visual C++ 6.0 Enterprise Edition
- Microsoft Visual C++ 5.0 Professional Edition
- Microsoft Visual C++ 6.0 Professional Edition
- Microsoft Visual C++ 6.0 Standard Edition
This article was previously published under Q103725
SUMMARY
The following sample code demonstrates how to pass variables of type char, short, and long from a Microsoft C program to a Microsoft Macro Assembler (MASM) program by reference.
MORE INFORMATION
The following sample includes one C file and three different assembly files. The three assembly files demonstrate how to pass variables by reference in small and large model for MS-DOS and in flat model for Windows NT. Link only the appropriate assembly module to the C module.
Note that MASM 6.1 or later and the C/C++ version 8.0 32-bit compiler that ships with Visual C++, 32-bit Edition, are required to build the flat model Windows NT version.
Sample Code
// Filename: CMAIN.C // Compile options needed: /c (and /AL for large model) #include <stdio.h> extern void MasmSub (char *, short *, long *); char charvar = 'a'; short shortvar = 1; long longvar = 32768L; void main (void) { printf ("%c %d %ld\n", charvar, shortvar, longvar); MasmSub (&charvar, &shortvar, &longvar); printf ("%c %d %ld", charvar, shortvar, longvar); }
Sample Code for MS-DOS Small Model Version
; Filename: MASMSUB.ASM ; Assemble options needed for MASM: /MX ; Assemble options needed for ML: /c /Cx .MODEL small, C ;.MODEL ... C tells the assembler that .286 ; parameters are pushed from right to left. .CODE MasmSub PROC uses si, \ pchar:PTR, \ pshort:PTR, \ plong:PTR mov si, pchar ;Load SI with the address of the char variable. mov BYTE PTR [si], "z" mov si, pshort ;Load SI with the address of the short variable. add WORD PTR [si], 9 mov si, plong ;Load SI with the address of the long variable. add WORD PTR [si], 1 ;Increment the low word of the long variable ;by 1. adc WORD PTR [si+2],0 ;Increment the high word. ret MasmSub ENDP END
Sample Code for MS-DOS Large Model Version
; Filename: MASMSUB.ASM ; Assemble options needed for MASM: /MX ; Assemble options needed for ML: /c /Cx .MODEL large, C ;.MODEL ... C tells the assembler that .286 ; parameters are pushed from right to left. .CODE MasmSub PROC uses es si, \ pchar:PTR, \ pshort:PTR, \ plong:PTR les si, pchar ;Load ES:SI with the address of the char variable. mov BYTE PTR es:[si], "z" les si, pshort ;Load ES:SI with the address of the short ;variable. add WORD PTR es:[si], 9 les si, plong ;Load ES:SI with the address of the long variable. add WORD PTR [si], 1 ;Increment the low word of the long variable ;by 1. adc WORD PTR [si+2],0 ;Increment the high word. ret MasmSub ENDP END
Sample Code for Windows NT Flat Model Version
; Filename: MASMSUB.ASM ; Assemble options needed for ML: /c /Cx /coff .386 ;.MODEL ... C tells the assembler that .MODEL flat, C ; parameters are pushed from right to left. .CODE MasmSub PROC uses esi, \ pchar:PTR, \ pshort:PTR, \ plong:PTR mov esi, pchar ;Load ESI with the address of the char variable. mov BYTE PTR [esi], "z" mov esi, pshort ;Load ESI with the address of the short ;variable. add WORD PTR [esi], 9 mov esi, plong ;Load ESI with the address of the long variable. inc DWORD PTR [esi] ;Increment the long variable by 1. ret MasmSub ENDP END
The following is the output of the program:
a 1 32768 z 10 32769
Additional query words: 8.00 9.00 mixed language
Keywords: kbhowto kblangc kbcode KB103725