Linux at &t Assembly__linux

1. The first operand is source and the second is destination (just the opposite of Intel).

Copy the contents of the EAX register to EBX:

MOVL    %eax,%EBX

2. Register before the name to add%

3. Add $ immediately before the number. Static C-language variables are also prefixed with $

4. The size of the operand is determined by the last character (b,w,l) of the operator. B:1 byte; W:2 bytes; L:4 bytes

5. Memory Operation:

Section:disp (base, index, scale)

Quite with Intel's

Section:[base + Index*scale + disp]

For constants that are used as scale and disp, do not prefix $

The following is a comparison of the Intel and at&t format assembly code:

+------------------------------+------------------------------------+
|       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 |