; tuta4.asm
; using	aliases, bit names and conditional loops
        list	p=p16f84
        radix	hex
	include "p16f84.inc"

; high speed >4mhz osc
; disable watchdog timer
	__config _HS_OSC & _WDT_OFF       

#define	page0 bcf STATUS,5
#define	page1 bsf STATUS,5

count	equ 0x0c	; counter storage
ncount	equ 0x0d	; count down storage register
mcount	equ 0x0e	; count down storage register
ocount	equ 0x0f	; count down storage register
shift	equ 0x24	; temporary pattern register	
w	equ 0		; working register flag
f	equ 1		; file register flag
c	equ 0		; carry flag

	org 0		 ; reset vector
	call 5		 ; call start of program
       	org 4		 ; interrupt vector
	call 5		 ; call start of program
       	org 5		 ; start of program memory

       	clrf PORTA	 ; clear port a data register
       	clrf PORTB	 ; clear port b data register

       	page1		 ; page1

        movlw b'00000001' 
       	movwf TRISA	 ; set ra0 as a input, the rest are output
       	clrf TRISB	 ; set all port b as output (clear direction reg)

       	page0		 ; page0

        bcf     STATUS,C        ; disable carry flag
        movlw   b'00000001'     ; initial bit pattern
        movwf   shift           ; store pattern

scanbut
	btfsc	PORTA,0		; test porta for button press - clear means pressed
	goto	rainbow		; continue present pattern
	goto	patchn		; pattern change

rainbow	movf	shift,w		; puts the contents of shift into W
	movwf	PORTB		; puts the contents of W into portb
	call	pause		; count to 65,000
	clrf	PORTB		; all LEDs off
        rlf	shift,f		; next LED on
	goto	scanbut

patchn	movlw	b'00000001'	; all blue
	movwf	PORTB
	call	pause
        clrf	PORTB
	rlf	shift,f
	bcf	PORTA,0		; clear out porta,0
	goto	scanbut

pause	movlw	0xff 
	movwf	mcount
loadn	movlw	0xff
	movwf	ncount
deco	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	decfsz	ocount,f
	goto	deco
	decfsz	mcount,f
	goto	loadn
	return
end