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Re-arrange some VDP writes so that the address register gets setup properly for the FIFO-fill while still avoiding a freeze
author Mike Pavone <pavone@retrodev.com>
date Sun, 08 Sep 2013 17:25:27 -0700
parents 30f1d4c90900
children
line wrap: on
line source

	dc.l $0, start
	dc.l empty_handler
	dc.l empty_handler
	;$10
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	;$20
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	;$30
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	;$40
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	;$50
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	;$60
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	;$70
	dc.l HINT
	dc.l empty_handler
	dc.l VINT
	dc.l empty_handler
	;$80
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	;$90
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	;$A0
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	;$B0
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	;$C0
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	;$D0
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	;$E0
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	;$F0
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	dc.l empty_handler
	dc.b "SEGA"
empty_handler:
	rte
start:
;background and sprite test

ButtonState	equ	$FFFFEFF0
ButtonStateNew	equ	ButtonState+2
PalAddress equ ButtonStateNew+2

CRAMXferSizeCmd equ $9308
CRAMDMACmd equ $C0000080

	move.b  #$40, $A10009
	move.l	#$C00000, a4
	move.l	#$c00004, a5

	move.l	#$0, a7

	move.w	#$8004, (a5)
	move.w	#$8104, (a5)	;turn off display
	;move.w	#$8200, (a5)	;Table A = 0000
	;move.w	#$8400, (a5)	;Table B = 0000
	;move.w	#$857C, (a5)	;Sprite Table = F800
	move.w	#$8B00, (a5)		;set full screen vertical and horizontal scrolling
	move.w  #$8C01, (a5)    ;H40 mode, no shadow/hilight, no interlace
	;move.w	#$8D3F, (a5)	;H Scroll = FC00
	;move.w	#$9001, (a5)	;64x32 scroll tables





	;move #$2300, SR
	move.b	#0, $a10003
WaitStart:
	btst.b #5, $a10003
	bne.s WaitStart

Top:

	lea	BgData(pc), a0 ;set DMA source address
	move.l a0, d7
	sub.l	#258, d7
	move.w	#$9500, d6
	ror.l	#1, d7
	move.b	d7, d6
	move.w	d6, (a5)
	ror.l	#8, d7
	move.b	d7, d6
	add.w	#$100, d6
	move.w	d6,(a5)
	ror.l	#8, d7
	move.b	d7, d6
	add.w	#$100, d6
	and.b	#$7F, d6
	;move.w	d6,(a5)




	move.l  #$94AE9342, (a5) ;set DMA length

	move.w #$8F00, (a5) ;set auto-increment to 0

	move.w	#$8144, (a5) ;display on, DMA off
	move.l #$40000000, (a5) ;Setup VRAM writes


	addq #1, a5
WaitVBlank:
	btst.b #3, (a5)
	beq.s WaitVBlank
WaitActive:
	btst.b #3, (a5)
	bne.s   WaitActive

	move.l d0, (a4) ;fill FIFO
	move.l d0, (a4)
	move.w d0, (a4)
	subq #1, a5
	move.w #$8114, (a5) ;display off, DMA on
	nop	;let FIFO drain
	nop
	nop
	move.w d6, (a5) ;finish setting DMA source
	move.l #$C0000080, (a5)

	bra Top



HINT:
	rte
VINT:
	bsr	ReadPad
	rte


ReadPad:
	move.b	#$FF, $a10003	;set TH for controller A
	move.b	$a10003, d0	;CBRLUD
	andi.b	#$3F, d0
	move.b	#0, $a10003
	move.b	$a10003, d1	;SA00UD
	andi.b	#$30, d1
	lsl.b	#2, d1
	or.b	d1, d0		;SACBRLUD
	not.b	d0
	move.b	(ButtonState).w, d1
	eor.b	d0, d1
	and.b	d0, d1
	move.b	d0, (ButtonState).w
	move.b	d1, (ButtonStateNew).w

	rts


BgData:
	incbin  dcolor.bin