Somando 8 bytes e mostrando na tela

;Soma de 8 bytes
;Lincoln Cesar dos Reis Arantes
;https://www.tutorialspoint.com/compile_asm_online.php

section .text
   global _start        ;must be declared for using gcc

_start:                 ;tell linker entry point

   mov     esi, 8       ;pointing to the rightmost digit
   mov     ecx, 8       ;num of digits
   clc
add_loop:
   mov  al, [numero1 + esi]
   adc  al, [numero2 + esi]
   aaa
   pushf
   or   al, 30h
   popf

   mov  [soma + esi], al
   dec  esi
   loop add_loop

   mov  edx,len         ;message length
   mov  ecx,msg         ;message to write
   mov  ebx,1           ;file descriptor (stdout)
   mov  eax,4           ;system call number (sys_write)
   int  0x80            ;call kernel

   mov  edx,9           ;message length
   mov  ecx,soma            ;message to write
   mov  ebx,1           ;file descriptor (stdout)
   mov  eax,4           ;system call number (sys_write)
   int  0x80            ;call kernel

   mov  eax,1           ;system call number (sys_exit)
   int  0x80            ;call kernel

section .data
msg db 'A soma é:',0xa
len equ $ - msg
numero1 db '22389001'
numero2 db '23456211'
soma db  '        '