Tuenti contest (Assembler)

; hard_sum tuenti contest (Assembler)
; by DjThD

    include \masm32\include\masm32rt.inc
    include \masm32\include\kernel32.inc
    include \masm32\include\msvcrt.inc
    includelib \masm32\lib\kernel32.lib
    includelib  \masm32\lib\msvcrt.lib

__p__iob proto c

    .data?
    .data
      buffer db 128 dup(0)
      bufferlength equ $-buffer

      formatonumero db '%i',10,0

    .code

start:
    call main
    exit

main proc
    call __p__iob
    push eax
    push bufferlength
    push 1
    push offset buffer
    call crt_fread
    add esp,010h

    mov esi, offset buffer
    dec esi
    xor ecx, ecx
    mov ecx, 10
    xor edi, edi
    xor ebx, ebx
    mov bl, '0'
    xor eax, eax

    push ebp
    xor ebp, ebp

_main_check:
    sub bl, '0'
    mul ecx
    add eax, ebx
_main_avanzar:
    inc esi
    mov bl, byte ptr [esi]
    cmp bl, ' '
    je _main_continuar
    cmp bl, '+'
    je _main_continuar
    cmp bl, '-'
    je _main_negativo
    cmp bl, 10
    je _main_nuevalinea
    test bl, bl
    jz _main_finalizar
    cmp bl, 4
    jne _main_check
    cmp bl, '9'
    jg _main_avanzar
    cmp bl, '0'
    jl _main_avanzar
    jmp _main_finalizar
_main_negativo:
    or ebp, 00000001h
    jmp _main_avanzar
_main_nuevalinea:
    or ebp, 00000100h
    jmp _main_continuar
_main_finalizar:
    or ebp, 00000110h
_main_continuar:
    test ebp, 00000001h
    jz _main_noesNegativo
    mov ecx, eax
    xor eax, eax
    sub eax, ecx
_main_noesNegativo:
    add edi, eax
    test ebp, 00000100h
    jz _main_noImprimir
    push edi
    push offset formatonumero
    call crt_printf
    add esp, 8
    xor edi, edi
_main_noImprimir:
    and ebp, 000000F0h
    xor eax, eax
    mov bl, '0'
    mov ecx, 10
    test ebp, 00000010h
    jz _main_check

    pop ebp
    ret
main endp
end start