g2ej6.asm

format PE
entry main

section '.text' code readable executable

  
main:   
  push    str_intro
  push    format_output
  call    [printf]
  add     esp,8

  push    str_input
  push    format_input
  call    [scanf]
  add     esp,8

  mov     esi,str_input
  xor     eax,eax
  xor     ebx,ebx
  xor   ebx,ebx
  xor   edx,edx

_bucle:

  cmp     byte[esi],0
  je      _control

  movzx   eax,byte[esi]
  add     [8*eax+contadores],1
  add     esi,1
  jmp     _bucle


_control:
  cmp   bl,[contadores+edx*8]
  jl    _nuevomayor

_incremento:
  inc   edx
  cmp   edx,256
  je    _fin
  jmp   _control

_nuevomayor:
  movzx ebx,[contadores+edx*8]
  jmp   _incremento

_fin:

  push    ebx
  push    format_output2
  call    [printf]
  add     esp,8

  push    num
  push    format_input
  call    [scanf]
  add     esp, 8

  push    0
  call    [exit]
  ret

section '.data' data readable writeable

contadores     rb  256
str_input      dd "%s",0
num            dd ?
format_input   db "%s",0
format_output  db "%s",10,0
format_output2 db "%d",10,0
str_intro      db "Ingrese la string:",10,0

section '.idata' data import readable

include "macro\import32.inc"
library msvcrt, "MSVCRT.DLL"
import msvcrt,\
       printf ,'printf',\
       scanf  ,'scanf',\
       exit   ,'exit'