RosettaCodeData/Task/Fork/X86-Assembly/fork.x86

; x86_64 linux nasm

%include "/home/james/Desktop/ASM_LIB/Print.asm"
%include "/home/james/Desktop/ASM_LIB/Sleep.asm"

section .data

parent: db "Parent: "
child: db "Child: "
newLine: db 10

section .text

global _start

_start:
  mov rax, 57 ; fork syscall
  syscall
  cmp rax, 0 ; if the return value is 0, we're in the child process
  je printChild

  printParent: ; else it's the child's PID, we're in the parent

    mov rax, 1
    mov rdi, 1
    mov rsi, parent
    mov rdx, 8
    syscall

    mov rax, 39 ; sys_getpid
    syscall
    mov rdi, rax
    call Print_Unsigned

    mov rax, 1
    mov rdi, 1
    mov rsi, newLine
    mov rdx, 1
    syscall

    mov rdi, 1 ; sleep so the child process can print befor the parent exits
    call Sleep ; you might not see the child output if you don't do this

    jmp exit

  printChild:

    mov rdi, 1
    call Sleep ; sleep and wait for parent to print to screen first

    mov rax, 1
    mov rdi, 1
    mov rsi, child
    mov rdx, 7
    syscall

    mov rax, 39 ; sys_getpid
    syscall
    mov rdi, rax
    call Print_Unsigned

    mov rax, 1
    mov rdi, 1
    mov rsi, newLine
    mov rdx, 1
    syscall

  exit:
    mov rax, 60
    mov rdi, 0
    syscall