NasmLessons/01-helloworld.asm

;;; Required packages: nasm, ld
;;; compile commands:
;;;     nasm -f elf 01-helloworld.asm -o bin/01-helloworld.o
;;;     ld -m elf_i386 -s -o bin/01-helloworld.out bin/01-helloworld.o

section .data
    msg db 'Hello, world!', 0xa ; db - define bytes, 0xa - code of \n
    len equ $ - msg

section .text
    global _start ; _start label is an entry point

_start:
    ; output 
    mov eax, 4 ; 4 - system call sys_write
    mov ebx, 1 ; 1 - file descriptor stdout 
    mov ecx, msg ; text 
    mov edx, len ; text size
    int 0x80 ; processor interruption to run syscall 

    ; exit code 
    mov eax, 1 ; 1 - system call sys_exit
    mov ebx, 0 ; 0 - error code 0
    int 0x80 ; processor interruption to run syscall