x86 Assembly

The assembly language that comes with x86 processors.

• Little Endian

Flavours

• x86 Assembly(Intel)
• x86 Assembly(AT&T)

Concepts

• x86 CPU Flags
• Calling Convention
• x86 Globals
• x86 Variable Dereferencing

Tools

• NASM is a popular assembler that can compile x86 code

Boilerplate (Nasm)

SECTION .data
msg     db      'Hello World!', 0Ah     ; assign msg variable with your message string
 
SECTION .text
global  _start
 
_start:
    mov     edx, 13     ; number of bytes to write - one for each letter plus 0Ah (line feed character)
    mov     ecx, msg    ; move the memory address of our message string into ecx
    mov     ebx, 1      ; write to the STDOUT file
    mov     eax, 4      ; invoke SYS_WRITE (kernel opcode 4)
    int     80h