Reverse

.MODEL SMALL
.STACK 100H
.DATA

; The string to be printed
STRING DB 'B F K L V', '$'

.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