ej10.asm

format PE
entry main
section '.text' code readable executable

main:
  push label_input
  push _format_output
  call [printf]
  add  esp, 8

  push buffer
  push _format_input
  call [scanf]
  add  esp, 8

  xor   ebx, ebx
  mov ebx, buffer


procesa:
  movzx eax, byte[ebx]
  cmp   eax, 0
  je    termina

  cmp al, $41
  jl  guardachar
  cmp al, $5b
  jl  mayus

  cmp al, $61
  jl guardachar
  cmp al, $7b
  jl  minus

mayus:
  cmp al, $4d     ; caracteres >=M, no es necesaria mas magia
  jg resta

  sub al, $d
  sub al, $40
  add al, $5a

  jmp guardachar

minus:
  cmp al, $6d     ; caracteres >=m, no es necesaria mas magia
  jg resta

  sub al, $d
  sub al, $60
  add al, $7a

  jmp guardachar

resta:
  ; resta 13
  sub   al, $D
  jmp   guardachar

guardachar:
  ; guardo en memoria
  mov [ebx], al

  add   ebx, 1
  jmp   procesa


termina:
  push buffer
  push _format_output
  call [printf]
  add  esp, 8

  push buffer
  push _format_input
  call [scanf]
  add  esp, 8

  ret

section '.data' data readable writeable
string rb 128

_format_input   db "%s",0
_format_output  db "%s",10,0

buffer            dq ?
label_input       db "Ingrese frase a encriptar:",10,0

section '.idata' data import readable

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