Does the masm32 package contain an example for a procedure which is callable from C (VC, gcc or whatever Windows C compiler)? I haven't found nothing.
Gunther
i seem to recall a thread in the old forum about "c-callable" routines
That is very simple if you use PROC/ENDP
include \masm32\include\masm32rt.inc
.code
; double foo(double x); // assuming __cdecl
foo proc c x:REAL8
fld x
fmul st,st
ret
foo endp
end
for the C program, add the corresponding *.obj file to the linker.
You may also take a look into Agner Fogs calling convention manual to look up parameter passing and return values.
Thank you qWord, that helped really. :t
Gunther
A minimal-overhead (32-bit integer) compare procedure for the CRT qsort function:
OPTION PROLOGUE:NONE
OPTION EPILOGUE:NONE
align 4
compare proc C p1:DWORD, p2:DWORD
mov eax, [esp+4]
mov edx, [esp+8]
mov eax, [eax]
mov edx, [edx]
sub eax, edx
ret
compare endp
OPTION PROLOGUE:PrologueDef
OPTION EPILOGUE:EpilogueDef
But at least for the Microsoft compilers there is no need to code the procedure in MASM, because you can create a naked function in C that has the same minimal overhead, and that can use exactly the same assembly code. I can't recall ever trying a naked function with GCC.
Hi Michael,
Quote from: MichaelW on January 13, 2013, 09:05:10 AM
But at least for the Microsoft compilers there is no need to code the procedure in MASM, because you can create a naked function in C that has the same minimal overhead, and that can use exactly the same assembly code. I can't recall ever trying a naked function with GCC.
thank you for providing the code. With gcc I've experimented with naked functions some years ago. It works, too. I will find the example code on one of my older machines. But your proposal shows the right direction.
Gunther
Hi Gunther,
Here is a Pelles C example calling the StdOut function from masm32.lib :
#include <stdio.h>
extern int __stdcall StdOut(char *);
int main(int argc,char *argv[])
{
StdOut("StdOut function called from masm32.lib\n");
return 0;
}
Thank you for the example, Erol. :t
Gunther
These are cool. Use a function pointer and assign it.