org 100h
        use16

Start:
        push    array
        push    length

        call    Procee

        ; res in address 'array'

        ret

Procee:
        push    BP
        mov     BP, SP

        mov     DI, word[BP + 6]
        mov     AX, word[BP + 4]

        mov     SI, DI
        add     SI, AX
        dec     SI

        mov     BH, 2
        div     BH

        xor     CX, CX
        mov     CL, AL

zaLoop:
        mov     AL, byte[DI]
        mov     AH, byte[SI]

        mov     byte[DI], AH
        mov     byte[SI], AL

        inc     DI
        dec     SI

        loop    zaLoop

        pop     BP
        ret     4

array   db      4, 9, 0, 5, 2, 6, 3
length  = $ - array