' ************************************
' * Scrolling Sign                   *
' * by Drew Hickman - copyright 1998 *
' *                                  *
' * bitvar b5 is a temp var used to  *
' * calculate other bitvars.         *
' ************************************

Symbol PortA=5
Symbol TrisA=$85
Symbol PortB=6
Symbol TrisB=$86
Symbol Brightness=2             'display brightness
Symbol Width=10                 'number of columns of LEDs in display
Symbol Delay=5                  'scroll speed (smaller=faster)
Symbol Length=35                'message length
                                'this equals (# of data-width of display)+1

        b6=0                    'the display's refresh loop counter
        b1=0                    'temporary table lookup result bitvar
        b2=0                    'scroll speed control (bigger=slower)
        b3=0                    'pointer to start of display (it moves)
        b4=0                    'temporary table lookup index bitvar
        poke trisa,0            'port A all output
        poke trisb,0            'port B all output
Main:   poke porta,1            'reset the 4017 chip step 1
        poke porta,0            'reset the 4017 chip step 2
        b6=0                    'reset the loop counter
        b5=b2+1 : b2=b5         'add one to the scroll speed control
        if b2=delay then Scroll 'scroll delay - is it time to scroll?
Loop:   b4=b3+b6                'set temp table lookup pointer
        lookup b4,(127,127,127,127,127,127,127,127,127,127,62,0,62,63,31,127,55,5,63,127,55,43,43,95,127,95,43,43,7,127,127,127,127,127,127,127,127,127,127),b1
        poke portb,b1           'light up the correct LEDs
        pause brightness        'so you can see the LEDs
        poke portb,127          'turn off all LEDs
        high 7                  'increment 4017 to next column
        b5=b6+1 : b6=b5         'increment loop counter
        if b6=width then Main   'if counter is width of display, reset refresh
        goto Loop               'else loop to next column
Scroll: b5=b3+1 : b3=b5         'move table pointer to start of display
        b2=0                    'reset speed counter
        if b3=length then Reset 'if at the end of the sign, then goto Next
        goto Loop               'loop to next column
Reset:  b3=0                    'we are at the end of the sign so reset pointer
        goto Main               'loop to next column