nasm fizzbuzz

fizzbuzz.asm

section .data
  fizz db "Fizz"
  buzz db "Buzz"
  newline db 10

section .bss
  digits resb 32

section .text
  global _start


_start:
  mov rax, 1
  mov r12, 100
  call _fizzbuzz
  mov rax, 60
  xor rdi, rdi
  syscall

_nextFB:
  call _sayNL
  mov rax, r9
  inc rax
_fizzbuzz:
  mov r9, rax
  cmp rax, r12
  je _finishFB
  mov r8, 0
  mov rcx, 3
  xor rdx, rdx
  div rcx
  mov rsi, fizz
  cmp rdx, 0
  jnz _fizzend
  call _sayFB
  mov r8, 1
_fizzend:
  mov rax, r9
  mov rsi, buzz
  xor rdx, rdx
  mov rcx, 5
  div rcx
  cmp rdx, 0
  jnz _buzzend
  call _sayFB
  mov r8, 1
_buzzend:
  mov rax, r9
  cmp r8, 0
  jnz _nextFB
  call _printNum
  mov rax, r9
  jmp _nextFB
_finishFB:
  ret

_sayFB:
  mov rax, 1
  mov rdi, 1
  mov rdx, 4
  syscall
  ret

_sayNL:
  mov rax, 1
  mov rdi, 1
  mov rsi, newline
  mov rdx, 1
  syscall
  ret

_initDigits:
  mov rax, digits
  mov rbx, rax
  add rbx, 32
_loopInitDigits:
  mov [rax], byte 0
  inc rax
  cmp rax, rbx
  jne _loopInitDigits
  ret

_digitfy:
  xor rdx, rdx
  mov rsi, 10
  div rsi
  mov [rbx], dl
  inc rbx
  cmp rax, 0
  jz _digitfyFin
  call _digitfy
_digitfyFin:
  ret

_printNum:
  push rax
  call _initDigits
  pop rax
  mov rbx, digits
  call _digitfy
_eachdig:
  dec rbx
  call _printDigit
  cmp rbx, digits
  jne _eachdig
  ret

_printDigit:
  add [rbx], byte 48
  mov rax, 1
  mov rdi, 1
  mov rsi, rbx
  mov rdx, 1
  syscall
  ret