- Prison Code Breaker Diary -

Here a simple example of exporting C function to Nasm.

;
; @author        [JaPh]
; @date            17 August, 2009
; @file            1.asm
; @site            http://xjaphx.blogspot.com/
;
; @command
; assemble     nasm -f elf -l 1.lst 1.asm
; link        gcc -o 1 1.o
; run        ./1
;

extern printf

SECTION .data

   message:    db    "[JaPh]Hello World",0
 
SECTION .text

global main                    ; entry point

main:                       
   push    ebp               
   mov        ebp, esp       
 
   push    dword message    ; address of 'message'
   call     printf            ; printf()
   add        esp, 4            ; 1 push = 4 bytes
 
   mov        esp, ebp
   pop     ebp
 
   mov     eax, 0
   ret

The equivalent program written in C

#include <stdio.h>

int
main( int argc, char *argv[] )
{
   printf("[JaPh]Hello World");
   return 0
}

Have fun!@