8086 program to reverse a string

.MODEL SMALL 
.STACK 100H 
.DATA 

; The string to be printed 
STRING DB 'This is a sample string', '$'

.CODE 
MAIN PROC FAR 
MOV AX,@DATA 
MOV DS,AX 

; call reverse function 
CALL REVERSE 

; load address of the string 
LEA DX,STRING 

; output the string
; loaded in dx 
MOV AH, 09H 
INT 21H 

; interrupt to exit
MOV AH, 4CH
INT 21H 

MAIN ENDP 
REVERSE PROC
    ; load the offset of
    ; the string 
    MOV SI, OFFSET STRING 

    ; count of characters of the; 
    ;string 
    MOV CX, 0H 

    LOOP1:
    ; compare if this is; 
    ;the last character 
    MOV AX, [SI] 
    CMP AL, '$'
    JE LABEL1 

    ; else push it in the; 
    ;stack 
    PUSH [SI] 

    ; increment the pointer; 
    ;and count 
    INC SI 
    INC CX 

    JMP LOOP1 

    LABEL1:
    ; again load the starting; 
    ;address of the string 
    MOV SI, OFFSET STRING 

        LOOP2: 
        ;if count not equal to zero 
        CMP CX,0 
        JE EXIT 

        ; pop the top of stack 
        POP DX 

        ; make dh, 0 
        XOR DH, DH 

        ; put the character of the; 
        ;reversed string 
        MOV [SI], DX 

        ; increment si and; 
        ;decrement count 
        INC SI 
        DEC CX 

        JMP LOOP2 

                
    EXIT:
    ; add $ to the end of string 
    MOV [SI],'$ '
    RET 
        
REVERSE ENDP 
END MAIN