swap proc
    push bp
    mov bp, sp
    sub sp, 2

    ; moving to registers ax,dx the values to swap
    mov bx, [bp+4]
    mov dx, [bx]

    mov bx, [bp+6]
    mov ax, [bx]

    ; swapping the values
    mov bx, [bp+4]
    mov [bx], ax

    mov bx, [bp+6]
    mov [bx], dx

    mov sp, bp
    pop bp
    ret 4
swap endp