#include <asm/unistd_32.h>
    .data
    .text
    .global _start
_start:
    pushl   %esi
    pushl   %edi
loopa:
    movl    $__NR_read, %eax
    movl    $0, %ebx
    addl    $4, %esp
    movl    %esp, %ecx
    movl    $1, %edx
    int     $0x80

    cmpl    $0, %eax
    jle     exit

    movl    (%esp), %esi
    cmpl    $'0', %esi
    jl  write

    movl    $'9', %edi
    cmpl    %esi, %edi
    jl  write

    movl    $'0', %edi
    movl    %edi, (%esp)
write:
    movl    $__NR_write, %eax
    movl    $1, %ebx
    movl    (%esp), %ecx
    subl    $4, %esp
    movl    $1, %edx
    int     $0x80

    jmp loopa
exit:
    popl    %edi
    popl    %esi
    movl    $__NR_exit, %eax
    movl    $0, %ebx
    int     $0x80