title: increment a string in x86 assembly
body: <p>How would you increment every character in a string by 3? 
  I'm actually new to assembly and i don't know much about it :/ 
  I have a code that takes STRING input and displays the output to the user on the screen</p>
  
  <pre><code>.model small
  .stack 100h
  .data
  
    STR1 DB "ENTER YOUR STRING : $"
    STR2 DB "YOUR STRING IS : $"
    INSTR1 DB 20 DUP("$")
    NEWLINE DB 10,13,"$"
  
  .code
  main proc
  
  Mov ax,@data
  mov ds,ax
  
      LEA SI,INSTR1
  
  ;Get STRING
  
      MOV AH,09H
      LEA DX,STR1
      INT 21H
  
      MOV AH,0AH
      MOV DX,SI
      INT 21H
  
      MOV AH,09H
      LEA DX,NEWLINE
      INT 21H
  
  ;PRINT STRING
  
  
      MOV AH,09H
      LEA DX,STR2
      INT 21H
  
      MOV AH,09H
      LEA DX,INSTR1+2
      INT 21H
  
       MOV AH,09H
      LEA DX,NEWLINE
      INT 21H
  
  
  mov ah,4ch
  int 21h
  main endp
  end main
  </code></pre>
  
  <p>Let's say if user writes 'HELLO' so the output i want is to be 'KHOOR'. So how would i do that? </p>