; *** Fastpixels ***
; (C)1988 by Brian Postma
; J.v.Hartenstraat 51
; 7576 VX Oldenzaal (NL)
; Tel:05410-14763

start:	movem.l		d0-d7/a0-a6,-(a7)
	move.l		#plane,d0	;my bitplane
	lea		pl,a0		;copper planes
	move.w		d0,6(a0)	;in copperlist ->low word
	swap		d0
	move.w		d0,2(a0)	;and hi word
	lea		gfxname,a1	;OpenGraphics lib
	move.l		4,a6
	jsr		-408(a6)
	move.l		d0,gfxbase
	move.l		d0,a0		;Need graphics lib
	move.l		$32(a0),oldcop	;for pointer to
	move.l		#newcop,$32(a0)	;copperlist->my clist
	move.l		$6c,oldirq	;Save oldirq pointer
	move.l		#newirq,$6c	;my interrupt
wait:	btst		#6,$bfe001	;check for
	bne		wait		;left mouse-button
	move.l		oldirq,$6c	;oldirq pointer back
	move.l		gfxbase,a1	;old copper
	move.l		oldcop,$32(a1)	;pointer back
	move.l		4,a6		;and close
	jsr		-414(a6)	;the graphics library
	movem.l		(a7)+,d0-d7/a0-a6
	rts

newirq:	bsr		bounce
	dc.w		$4ef9		;code for JMP
oldirq:	dc.l		0		;to old irq

bounce:	move.w		x,d0		;x coord
	move.w		y,d1		;y coord
	move.w		#40,d2		;Screen width
	lea		plane,a0	;bitplane pointer
	bsr		clrpixel	;clear old
back:	move.w		dx,d0		;delta x
	add.w		d0,x		;new x coord
	move.w		dy,d0		;delta y
	add.w		d0,y		;new y coord
	tst.w		x		;left border reached
	ble		negx		;Yes ??
	cmpi.w		#319,x		;right border reached
	bge		negx		;Yes ??
	tst.w		y		;Top border reached
	ble		negy		;Yes ??
	cmpi.w		#255,y		;Bottom border reached
	bge		negy		;Yes ??
	move.w		x,d0		;x coord
	move.w		y,d1		;y coord
	move.w		#40,d2		;Screen width
	lea		plane,a0	;bitplane pointer
	bsr		writepixel	;Write new
	rts
negx:	neg.w		dx
	bra		back
negy:	neg.w		dy
	bra		back
x:	dc.w	100
y:	dc.w	200
dx:	dc.w	2
dy:	dc.w	-2

; d0=x coord, d1=y coord, a0 = pointer to bitplane
; d2=screen width in bytes
; no other registers are used
clrpixel:
	move.b		#$b0,l+1	;change bset to bclr
writepixel:
	mulu		d2,d1		;y coord*screenwidth
	add.l		d1,a0		;Y Position
	move.w		d0,d1		;save x coord
	lsr.w		#3,d1		;Divide by 8
	and.w		#7,d0		;Which Bit
	move.w		#7,d2		;substract from 7
	sub.w		d0,d2		;coz pixel 0 = bit 7
l:	bset		d2,(a0,d1.w)	;set it
	move.b		#$f0,l+1	;reset to bset
	rts

newcop:	dc.w	$0092,$0038,$0094,$00d0	;DFFStart,DFFStop
	dc.w	$008e,$296a,$0090,$29fa	;DIWStart,DIWStop
	dc.w	$0180,$0000,$0182,$0fff	;Colors
pl:	dc.w	$00e0,$0000,$00e2,$0000	;BitPlane 1 pointer
	dc.w	$0100,$1000		;Bitplane 1 On
	dc.w	$ffff,$fffe		;End of Copperlist

plane:	blk.b	10240,0			;256 lines x 40 bytes

oldcop:		dc.l	0
gfxbase:	dc.l	0
gfxname:	dc.b	"graphics.library",0