User input and reverse string

.model small
.stack 100h
.data

v1 db 10 dup('$')

.code
main proc
       mov ax,@data
    mov ds,ax
    mov si,offset v1

 l1:


    mov ah,1
    int 21h

    cmp al,13
    je stop

    mov [si],al
    inc si

    jmp l1


  stop:
   mov si,offset v1
    mov cx,4

    jmp l2

 l2:
   mov bx,[si]
   push bx
   inc si

   loop l2

   mov cx,4
 l3:
   pop dx
   mov ah,2
   int 21h

   loop l3




    exit:
    mov ah,4ch
    int 21h
    main endp
end main