[Mingw-notify] [ mingw-Bugs-1506172 ] call library function from assembly

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Bugs item #1506172, was opened at 2006-06-15 04:02
Message generated for change (Settings changed) made by dannysmith
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>Category: non-mingw
Group: None
>Status: Closed
>Resolution: Works For Me
Priority: 5
Submitted By: Jan Kechel (foadjok)
Assigned to: Danny Smith (dannysmith)
Summary: call library function from assembly

Initial Comment:
The following code crashes under windows XP, while it
works properly with dos djgpp and linux gcc:

--- cut prog.c ---
#include <stdio.h>

extern void PrintStrings();

unsigned int Exported;

int main()
{
  Exported = 0xdeadbeef;
  PrintStrings();
  return 0;
}
--- end cut prog.c ---

--- cut printstr.asm ---
[BITS 32]                               ; Default is
32-bit code
[GLOBAL PrintStrings]                  ; export label
[EXTERN printf]                        ; external procedure
[EXTERN Exported]                      ; external variable

[SECTION .data]                         ; data segment

VersionString  db "Testversion 0.01",00h
PrintTemplate1  db "VersionString = '%s'", 0ah, 00h
PrintTemplate2  db "unsigned int Exported = 0x%08x",0ah,00h

[SECTION .text]                         ; code segment

PrintStrings:

                push    ebp
                mov     ebp, esp
                push    dword VersionString
                push    dword PrintTemplate1
                                        ; pass parameters
                call    printf         ; call C function
                push    dword [Exported]
                push    dword PrintTemplate2
                                        ; pass parameters
                call    printf         ; call C function
                mov     esp, ebp
                pop     ebp
                ret
--- end cut printstr.asm ---

To build the program we used:
under linux:
$ nasm -felf printstr.asm
$ gcc -o prog printstr.o prog.c
$ ./prog
-> works fine

version-numbers under linux:
gcc version 4.0.4 20060507 (prerelease) (Debian 4.0.3-3)
NASM version 0.98.38 compiled on May 17 2005

Tu build the program under windows and dos all exported
variables and external functions must have a leading
underscore (e.g. '_printf')
> nasm -fcoff printstr.asm
> gcc -o prog.exe printstr.o prog.c
> prog
-> crashes (general protection fault)

version-numbers under windows:
gcc -dumpversion: 3.4.2
NASM version 0.98


----------------------------------------------------------------------

>Comment By: Danny Smith (dannysmith)
Date: 2006-06-15 08:34

Message:
Logged In: YES 
user_id=11494

The fine manual says use
nasmw -f win32 

if you want win32 objects.

win32 objects havew PE COFF format, not standard COFF

Danny

----------------------------------------------------------------------

You can respond by visiting: 
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