GAS v.s. NASM

AT&T GCC GAS
http://sig9.com/articles/att-syntax
http://en.wikibooks.org/wiki/X86_Assembly/GAS_Syntax



NASM, X86, Intel
http://www.drpaulcarter.com/pcasm/

Now we saw some of the major differences between Intel syntax and AT&T syntax. I’ve wrote only a few of them. For a complete information, refer to GNU Assembler documentations. Now we’ll look at some examples for better understanding.

+------------------------------+------------------------------------+
|       Intel Code             |      AT&T Code                     |
+------------------------------+------------------------------------+
| mov     eax,1                |  movl    $1,%eax                   |   
| mov     ebx,0ffh             |  movl    $0xff,%ebx                |   
| int     80h                  |  int     $0x80                     |   
| mov     ebx, eax             |  movl    %eax, %ebx                |
| mov     eax,[ecx]            |  movl    (%ecx),%eax               |
| mov     eax,[ebx+3]          |  movl    3(%ebx),%eax              | 
| mov     eax,[ebx+20h]        |  movl    0x20(%ebx),%eax           |
| add     eax,[ebx+ecx*2h]     |  addl    (%ebx,%ecx,0x2),%eax      |
| lea     eax,[ebx+ecx]        |  leal    (%ebx,%ecx),%eax          |
| sub     eax,[ebx+ecx*4h-20h] |  subl    -0x20(%ebx,%ecx,0x4),%eax |