section .text

u64_to_dec:
  mov rcx, 10
  mov r8, rdi
  lea rdi, [rdi + 0x13]

  test rax, rax
  jnz .convert
  mov byte [rdi], '0'
  dec rdi
  jmp .pad

.convert:
  xor rdx, rdx
  div rcx
  add dl, '0'
  mov [rdi], dl
  dec rdi
  test rax, rax
  jnz .convert

.pad:
  inc rdi
.pad_loop:
  cmp rdi, r8
  jbe .done
  mov byte [rdi], ' '
  inc rdi
  jb .pad_loop

.done:
  ret