to_str.s

.section .data

divtable:
  .long 100, 10, 1, 0

.section .bss
.lcomm buffer, 16


.section .text

.globl _start
_start:
  pushl $256
  call to_str
  addl $4, %esp
  movl $1, %eax
  movl $0, %ebx
  int $0x80

.type to_str, @function
to_str:
  pushl %ebp
  movl %esp, %ebp
  movl $0, %edi 
  movl divtable, %edx
  movl 8(%esp), %eax
  pushl $0x0
  jmp to_str_loop

to_str_loop:
  movl divtable(, %edi, 4), %ebx
  cmpl $3, %edi
  jge to_str_end

  movl $0, %edx
  div %ebx
  
  cmpl $0, %eax
  jle to_str_end

  addl $48, %eax
  pushl %eax
  
  cmpl $0, %edx
  jle to_str_end

  movl %edx, %eax
  jmp to_str_next

to_str_next:
  addl $1, %edi
  jmp to_str_loop

to_str_end:
  jmp strcpy
 

strcpy:
  movl %esp, %esi 
  movl $buffer, %edi

  jmp strcpy_loop


strcpy_loop: 
  movb (%esi), %al
  movb %al, (%edi)
  addl $4, %esi
  incl %edi

  test %al, %al
  jnz strcpy_loop 

  jmp strcpy_end

strcpy_end:
  movl %ebp, %esp
  popl %ebp
  ret