; SoftScroller
; 1989 by Brian Postma
; J.v.Hartenstraat 51
; 7576VX Oldenzaal (NL)
; Tel:05410-14763

start:	movem.l		d0-d7/a0-a6,-(a7)
	lea		gfxname,a1	;Name of graphics library
	move.l		4,a6		;Execbase
	jsr		-408(a6)	;Open Library
	move.l		d0,gfxbase	;Rememer graphics base
	lea		intname,a1	;Name of intuition lib.
	jsr		-408(a6)	;Open Library
	move.l		d0,intbase	;Remember intuition base
	move.l		intbase,a6
	lea		osargs,a0	;Pointer to newscreen struct.
	jsr		-198(a6)	;Open Screen
	move.l		d0,screenbase	;Pointer to screen struct
	beq		quit		;Could I open it ??
	add.l		#84,d0		;Screenbase+84
	move.l		d0,rastport	;Is Rastport
	move.l		gfxbase,a6	
	move.l		rastport,a1
	clr.l		d0		;Color=0
	jsr		-234(a6)	;Setrast->Clear Screen
	move.l		screenbase,a0
	move.l		192(a0),d0	;Pointer to first bitplane
	move.w		d0,planes+6	;Low word in copperlist
	swap		d0
	move.w		d0,planes+2	;High word in copperlist
	move.l		gfxbase,a0	;gfxbase+$32=pointer to clist
	move.l		$32(a0),oldcop	;save old copperlist
	move.l		#newcop,$32(a0)	;My own copperlist
	move.l		$6c,oldirq	;Save old VBL irq pointer
	move.l		#newirq,$6c	;my VBL interrupt
wait:	btst		#6,$bfe001	;Left mouse button pressed ??
	bne		wait		;No !!
	move.l		oldirq,$6c	;Restore interrupt
	move.l		gfxbase,a0	;restore
	move.l		oldcop,$32(a1)	;old copperlist
	move.l		intbase,a6
	move.l		screenbase,a0
	jsr		-66(a6)		;Close the screen
quit:	movem.l		(a7)+,d0-d7/a0-a6
	rts

newirq:	movem.l		d0-d7/a0-a6,-(a7);Save regs
	bsr		scroll
	movem.l		(a7)+,d0-d7/a0-a6;Restore regs
	dc.w		$4ef9		;Code for 'JUMP'
oldirq:	dc.l		0		;Jump to oldirq

scroll:	move.l		gfxbase,a6
	move.l		#2,d0		;dx, 2 pixels to the left
	clr.l		d1		;dy
	move.l		#0,d2		;min x
	move.l		#0,d3		;min y
	move.l		#367,d4		;max x
	move.l		#15,d5		;max y
	move.l		rastport,a1	;rastport pointer
	jsr		-396(a6)	;ScrollRaster
	subq.w		#1,scrcount	;Counter for newtext
	beq		newtext		;is zero->new char
	rts				;else->bye ??
newtext:move.w		#5,scrcount	;newtext delay set
	move.l		gfxbase,a6
	move.l		rastport,a1
	move.l		#358,d0		;x
	move.l		#8,d1		;y
	jsr		-240(a6)	;move
	move.l		stringpointer,a0;pointer to string
	move.l		#1,d0		;1 char
	jsr		-60(a6)
	addq.l		#1,stringpointer;Next char
	cmpi.l		#endstring,stringpointer
	bne		notend		;end of string reached
	move.l		#string,stringpointer;Start al over
notend:	rts

newcop:	dc.w	$0092,$0028,$0094,$00d8	;DFFSTART,DFFSTOP->OverScan
	dc.w	$008e,$296a,$0090,$29fa	;DIWSTART,DIWSTOP
	dc.w	$0108,$0000,$010a,$0000	;BPL1MOD,BPL2MOD
	dc.w	$0096,$0020,$0100,$0000	;Sprites off,planes off
	dc.w	$0180,$0000,$0182,$0fff	;Colors
planes:	dc.w	$00e0,$0000,$00e2,$0000	;Plane1 low,high word
	dc.w	$8001,$fffe		;Wait till line 128 reached
	dc.w	$0100,$1000		;Bitplane 1 on
	dc.w	$9001,$fffe		;Wait till line 144 reached
	dc.w	$0100,$0000		;Bitplanes off
	dc.w	$ffff,$fffe		;Wait till end

osargs:	dc.w	0,0,368,16		;x-min,y-min,width,height
	dc.w	1			;depth 1 bitplane
	dc.b	0,1			;detailpen,blockpen
	dc.w	0,15			;viewmodes,type=customscreen
	dc.l	textattr,0		;textattr,title=none
	dc.l	0,0			;gadgets,bitmap
textattr:
	dc.l	fontname		;Fontname
	dc.w	9			;fontsize
	dc.b	0			;Style=normal
	dc.b	1			;flags=romfont

scrcount:	dc.w	1
oldcop:		dc.l	0
gfxbase:	dc.l	0
intbase:	dc.l	0
rastport:	dc.l	0
screenbase:	dc.l	0
stringpointer:	dc.l	string
intname:	dc.b	"intuition.library",0
gfxname:	dc.b	"graphics.library",0
fontname:	dc.b	"topaz.font",0
string:
 dc.b	"WRITTEN BY BRIAN POSTMA"
 dc.b	"      "
endstring: