From 68f00d9fa1d92861b5f326e28d1068507f47ccb4 Mon Sep 17 00:00:00 2001
From: alpine9000 <alex.g.brown@gmail.com>
Date: Sat, 26 Mar 2016 19:38:32 +1100
Subject: [PATCH] Slow double buffer

---
 024.simple_text/image.s       | 30 +++-----------
 024.simple_text/simple_text.s | 73 +++++++++++++++++++----------------
 2 files changed, 46 insertions(+), 57 deletions(-)

diff --git a/024.simple_text/image.s b/024.simple_text/image.s
index a0b31f8..079b679 100644
--- a/024.simple_text/image.s
+++ b/024.simple_text/image.s
@@ -1,31 +1,13 @@
 	include "includes.i"
 
-	xdef DisplayBitplane
+	xdef SwitchBuffers
 		
-LoadImage:
-	;; d0 - size
-	;; a1 - start address
-	;; a2 - InstallColorPalette(X) address
-
-	lea	bitplanes3,a0
-	bsr	LoadDiskData		; load data from disk
-
-	;; move.l	nextbitplane,a1		; decompress into offscreen bitplanesp(1/2)
-	
-	;; a0 = Input buffer to be decompressed. Must be 16-bit aligned!
-	;; a1 = Output buffer. Points to the end of the data at exit
-	jsr	Depack
-
-	jsr 	WaitVerticalBlank	; avoid tearing when we show the new image
-	jsr	(a2)			; install new color palette
-	jsr	DisplayBitplane		; display new image
-
-	rts
-	
-
-DisplayBitplane:
-	;; a0 - bitplane address
+SwitchBuffers:
+	;; offscreen - bitplane address
 	movem.l	d0/a0-a1,-(sp)
+	move.l	offscreen,a0
+	move.l	onscreen,offscreen
+	move.l	a0,onscreen
 	moveq.l	#0,d0
 	move.l	a0,a1
 	lea 	copperListBplPtr,a0
diff --git a/024.simple_text/simple_text.s b/024.simple_text/simple_text.s
index 22c20e3..1ce71de 100644
--- a/024.simple_text/simple_text.s
+++ b/024.simple_text/simple_text.s
@@ -2,9 +2,8 @@
 	
 	xdef 	PokeBitplanePointers
 	xdef	copperList
-	xdef 	bitplanes1
-	xdef 	bitplanes2
-	xdef 	bitplanes3
+	xdef	onscreen
+	xdef	offscreen
 	xdef	copperListBplPtr
 	
 byteMap:
@@ -25,52 +24,58 @@ Entry:
 	
 	move.w	#(INTF_SETCLR|INTF_VERTB|INTF_INTEN),INTENA(a6)	
 
-	lea	bitplanes1,a0
-	move.l	#4,d0		;color
+	move.l	offscreen,a0
+	move.l	#4,d0		; color#
 	jsr	CpuFillColor
-
-
-	jsr	DisplayBitplane	; select it	
-
-	if 0
-	lea	bitplanes2,a0
-	move.l	#3,d0		;color
-	jsr	CpuFillColor
-	endif
-
+	move.l	onscreen,a0
+	move.l	#4,d0		; color#
+	jsr	CpuFillColor	
+	
+	jsr	SwitchBuffers
 	
 	jsr	Init		; enable the playfield
 	
 .mainLoop:
-	jsr 	WaitVerticalBlank
-	jsr 	WaitVerticalBlank
-	jsr 	WaitVerticalBlank
-	jsr 	WaitVerticalBlank
-	jsr 	WaitVerticalBlank	
+	move.l	offscreen,a0
+	move.l	#4,d0		; color#
+	jsr	CpuFillColor
 
-	;; blitobject64
-	;; d0 - xpos
-	;; d1 - ypos
-	;; a0 - display
-	;; a1 - object
-	;; a2 - mask
-
-	;; add.l	#1,xpos
-	move.b	#0,d3
-	move.l  #0,xpos
+	move.l	direction,d0
+	add.l	d0,xpos
 	move.l	xpos,d0
 	move.l	#50,d1
-	lea	bitplanes1,a0
+	move.l	offscreen,a0
 	lea	text,a1
 	jsr	DrawText
+
+	jsr 	WaitVerticalBlank	
+	jsr	SwitchBuffers
+
+	cmp.l	#320-(26*8),xpos
+	ble	.notright
+	move.l	direction,d0
+	muls.w	#-1,d0
+	move.l	d0,direction
+	bra	.mainLoop
+.notright:
+	cmp.l	#0,xpos
+	bne	.mainLoop
+	move.l	direction,d0
+	muls.w	#-1,d0
+	move.l	d0,direction	
+	
 	bra	.mainLoop
 
+	
 text:
 	dc.b	"My first text on an Amiga!"
 	dc.b	0
 	align	4
 xpos:
 	dc.l	0
+direction:
+	dc.l	1
+	
 Level3InterruptHandler:
 	movem.l	d0-a6,-(sp)
 	lea	CUSTOM,a6
@@ -116,13 +121,15 @@ copperListBplPtr:
 InstallPalette:
 	include	"out/font-palette.s"
 	rts
+onscreen:
+	dc.l	bitplanes1
+offscreen:
+	dc.l	bitplanes2
 	section .bss	
 bitplanes1:
 	ds.b	IMAGESIZE+(512)
 bitplanes2:
 	ds.b	IMAGESIZE+(512*2)
-bitplanes3:
-	ds.b	IMAGESIZE+(512*3)
 startUserstack:
 	ds.b	$1000		; size of stack
 userstack: