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x86-64

Registers​

General Purpose Registers (64-bit)​

  • RAX, RBX, RCX, RDX
  • RSI, RDI, RBP, RSP
  • R8-R15

Segment Registers​

  • CS, DS, ES, FS, GS, SS

Index Registers​

  • RSI (Source Index)
  • RDI (Destination Index)

Data Movement​

MOV: Move data between registers or memory​

  • MOV reg, imm
  • MOV reg, mem
  • MOV mem, reg

Arithmetic and Logic​

ADD, SUB, IMUL, IDIV, INC, DEC​

  • ADD dest, src
  • SUB dest, src
  • IMUL dest, src (signed multiplication)
  • IDIV divisor (signed division)
  • INC reg/mem, DEC reg/mem

AND, OR, XOR, NOT​

  • AND dest, src
  • OR dest, src
  • XOR dest, src
  • NOT reg/mem

Control Flow​

JMP, JE (Jump if Equal), JNE (Jump if Not Equal), JG, JL, JGE, JLE​

  • JMP label
  • JE label
  • JNE label
  • JG label (greater)
  • JL label (less)
  • JGE label (greater or equal)
  • JLE label (less or equal)

CALL, RET​

  • CALL procedure
  • RET

Comparison​

CMP: Compare two values​

  • CMP operand1, operand2

Stack​

PUSH, POP​

  • PUSH reg/mem
  • POP reg/mem

System Calls​

SYSCALL​

  • Used for making system calls in x64 assembly.

Example Code​

section .data
  my_variable dq 42           ; Define a 64-bit variable with initial value 42

section .text
global _start

_start:
  MOV RAX, my_variable      ; Load my_variable into RAX
  ADD RAX, 8                ; Add 8 to RAX
  MOV RBX, 10               ; Load 10 into RBX
  CMP RAX, RBX              ; Compare RAX and RBX
  JE  equal_label           ; Jump to equal_label if RAX equals RBX
  JNE not_equal_label       ; Jump to not_equal_label if RAX doesn't equal RBX

equal_label:
  ; Code to execute if RAX equals RBX
  JMP end_label             ; Jump to end_label

not_equal_label:
  ; Code to execute if RAX doesn't equal RBX

end_label:
  ; Code to execute at the end of the program
  MOV RAX, 60               ; syscall: exit
  XOR RDI, RDI              ; status: 0
  SYSCALL