TN VXL 2-2

        list    p=PIC18f8722
        #include p18f8722.inc
        CONFIG  OSC = HS, WDT = OFF, LVP = OFF
        #define LED LATD
        #define LED_IO TRISD
        #define BUTTON PORTA,RA5
        #define BUTTON_IO TRISA,RA5
; Begin
        code    0
        goto    initialize

; Memory mapping
        udata
counter res     .3
direction       res     .1
direction_bit   equ     0
        #define DIRECTION direction,direction_bit
; Start
        PRG code
initialize
        clrf    LED_IO
        clrf    LED
        movlw   H'0F'
        movwf   ADCON1
        bsf     BUTTON_IO

main    btfsc   BUTTON          ; if    button not pushed
        bra     led_change      ; then  change LED
        btg     DIRECTION       ; else  change direction
button_pushed
        btfss   BUTTON
        bra     button_pushed
led_change
        btfsc   DIRECTION
        bra     led_change1
        incf    LED
        bra     led_change2
led_change1
        decf    LED
led_change2
        call    delay_500ms
        bra     main

delay_400us
        movlw   .249
        movwf   counter
        nop
delay_400us_loop
        nop
        decfsz  counter
        bra     delay_400us_loop
        return

delay_500ms
        movlw   .5
        movwf   counter + 1
delay_500ms_loop1
        movlw   .250
        movwf   counter + 2
delay_500ms_loop2
        call    delay_400us
        decfsz  counter + 2
        bra     delay_500ms_loop2
        decfsz  counter + 1
        bra     delay_500ms_loop1
        return

        end