Newsgroups:	comp.os.msdos.djgpp
From:	patrick AT spirit DOT gun DOT de (Patrick Fedick)
Subject:	Problem combining DJGPP and MASM
Reply-To:	patrick AT pfp DOT de
Organization:	private
Message-ID:	<E95tKA.2I0@spirit.gun.de>
Date:	Thu, 24 Apr 1997 20:43:22 GMT
Lines:	60
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Hello,

I'm new to DJGPP, and have some problems combining my assembly functions
with gcc. It seems to be impossible, to use local data in my assembly
modules. If I load a register with the value of a variable, I allways get
the value of the first variable. Example:

   var1	  dd 1
   var2   dd 2
   var3   dd 3
   [...]
   mov eax,var3

If I return to the calling c-function and print the value, it contents
a 3. I don't know why. If I load the eax-register with an absolute
value (like mov eax,3), the c-function prints the right value. 

So I thought there goes something wrong with the data segments, but I
don't use any in my assembly function, and I thought gcc wouldn't use
any either (or am I wrong?).

Here is an example:
--------------------------------------------------------------------------
/* Assembly-Module, called testasm.asm */
.586p
.model flat,c
.code
align 4

var1	dd 1
var2	dd 2

getvar2 proc near public
  mov eax,var2
  ret
getvar2 EndP
END
--------------------------------------------------------------------------
/* C-Module, called test.c */
#include <stdio.h>
unsigned long getvar2 ();

main() {
  printf ("The value is: %u\n",getvar2 () );
}
--------------------------------------------------------------------------
I have compiled the assembly module with MASM 6.11d: ml /c /coff testasm.asm
and the c-module with gcc 2.7.2.1: gcc -o test.exe -O testasm.obj test.c

If I start this program, it returns: "The value is: 1", but it must be "2".
I altered the function to "mov eax,cs:var2", but it still returns "1".

Can anyone explain me this? It would be great, if someone can help me to
fix this problem.

Thanks,

Patrick
-- 
Patrick Fedick     <patrick AT pfp DOT de>

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