NASM Coding: Basics - Program Examples

3. ; The string "6-7" will be printed 5 times on the screen (using a loop):
   
   section .data
       message db "6-7", 10    ; message = "6-7\n"
       msg_len equ $ - message ; msg_len = len(message)
   
   section .text
       global _start
   
   _start:
       mov rbx, 5        ; Put 5 in rbx
   
   loop_start:           ; The loop_start label
       dec rbx           ; Decrement rbx -= 1
       mov rax, 1        ; Put the 'write' syscall code in rax
       mov rdi, 1        ; File descriptor: stdout (screen)
       mov rsi, message  ; Use the content in 'message'
       mov rdx, msg_len  ; length
       syscall
       
       cmp rbx, 0        ; Check if (rbx == 0)
       jne loop_start    ; If not equal, jump back to loop_start
   
       mov rax, 60       ; Put the 'exit' syscall code in rax
       mov rdi, 0        ; Put 0 in rdi (1st argument to _exit)
       syscall           ; Call _exit(rdi), which is _exit(0)