; vim:fileencoding=utf-8:ft=nasm:foldmethod=marker
;     _   ___ _____ 
;    (_) /   |  _  |
;     _ / /| | |/' |
;    | / /_| |  /| |
;    | \___  \ |_/ /
;    | |   |_/\___/ 
;   _/ |            
;  |__/             
;
;  j40     : 11399628#USP
;  made_in : Sao_Carlos, SP, BR, 2020_12
;
;  --- x86_64 nasm assembly: Hello World! ---

; >> This program writes "Hello, World!" to
; stdout.

;  MOUNTING AND LINKING {{{
;   
;  $ yasm -g dwarf2 -felf64 hello.asm -o temp.o 
;  $ ld temp.o -o hello
;  $ rm temp.o
;  
;  (the "-g dwarf2" can be changed to just "-g" on nasm,
;  or removed if debugging is not needed)
;
; }}}

global _start

section .text

_start: nop

        ; write message to stdout 
        mov rax, SYS_WRITE
        mov rdi, FD_STDOUT 
        mov rsi, str_msg 
        mov rdx, len_msg
        syscall

        ; exit program
        mov rax, SYS_EXIT
        xor rdi, rdi
        syscall


section .data

    ;syscalls
    SYS_WRITE:  equ 1
    SYS_EXIT:   equ 60

    ;file descriptor
    FD_STDOUT:  equ 1

    ; the message
    str_msg:    db "Hello, World!", 10
    len_msg:    equ $ - str_msg