==== Horizontal Double Screen Bitmap Scroller ====
== Done with VSP ==
{{:base:vsp.zip|Download}}
<code>
//---------------------------------------------------------------------------------------------------------------------
// Horizontal Double Screen Bitmap Scroller, done with VSP
// For the C64pixels.com Double Screen Pixeling Compo
// Code: Cruzer/CML, April 2011
// Based on a routine from Codebase64 by Martin Piper
// Can be used/modified/distributed freely
// Asm: KickAss 3.15
// Tab: 16 chars
//---------------------------------------------------------------------------------------------------------------------
// Picture size: 80x25 chars, in either multicolor or hires bitmap.
// Gfx can be imported either as two c64 pics or a PNG file.
// C64 pics:
// - Set importMode = C64_MODE
// - Save pics as "pic0.prg" and "pic1.prg", or *.p00
// - For multicolor pics use Koala format
// - For hires pics use Topaz Hires Editor format (starts with color screen, followed by bitmap at a $400 offset)
// - Set c64FileType to "prg" or "p00"
// PNG:
// - Set importMode = PNG_MODE
// - Save pic as "pic.png"
// - Size: 640x201 (only the lower 200 lines are used for gfx)
// - The upper line is used for defining the c64 palette, with hires or multicolor sized pixels depending on the mode
// - The pixel to the right of the palette defines the background color
// For both formats:
// - Set multiColorMode = true/false
// - Set borderColor manually or leave it as -1 to make it the same as the bg color
// - Adjust sineLength for slower/faster speed
//---------------------------------------------------------------------------------------------------------------------
// Code info:
// VSP can only push the screen 40 chars, so with extended borders the visible pic could only be 78 chars wide.
// To get full double screen size I added an extra displaced bitmap screen for the two last chars.
// When switching to/from this, the d800 colors need to be moved, since they can't be bank switched.
// This would of course have been easier with linecrunch, but I wasn't in the mood for finding out whether it was
// possible while keeping the gfx 25 chars high.
//---------------------------------------------------------------------------------------------------------------------
//params...
.enum {PNG_MODE, C64_MODE}
.const importMode = PNG_MODE
.const multiColorMode = true
.const c64FileType = "prg"
.const sineAmp = $150
.const sineLength = $cc
.var borderColor = -1
//---------------------------------------------------------------------------------------------------------------------
//zeropage...
.const pnt0 =		$02 //2
.const pnt1 = 		$04 //2
.const xPos = 		$06 //1
.const yPos = 		$07 //1
.const xPosChr =	$08 //1
.const source =		$09 //2
.const target =		$0b //3
.const srcPos =		$0e //1
.const destPos =	$0f //1
.const destPosBitmap = 	$10 //2
.const dir = 		$12 //1
.const d16 = 		$13 //1
.const dmaDelay = 	$14 //1
//---------------------------------------------------------------------------------------------------------------------
//memory...
.const basic =		$0801 //080f
.const tune =		$1000 //1fff
.const main =		$2000 //3fff
.const sineLo =		$4400 //47ff
.const sineHi =		$4800 //4bff
.const bitmapLut =	$4c00 //8bff
.const screen =		$8c00 //8fff
.const screenLut =	$9000 //97ff
.const d800Lut =	$9800 //9fff
.const bitmap =		$a000 //bfff
.const bitmap2 =	$c000 //dfff
.const screen2 =	$e000 //e3ff
//---------------------------------------------------------------------------------------------------------------------
.const unused = $fff6
.const border = unused
.const irqLine = $2d
.const ProcessorPortDDRDefault = %00101111
.const ProcessorPortAllRAMWithIO = %00100101
.const CIA1InterruptControl =	$dc0d
.const CIA1TimerAControl =	$dc0e
.const CIA1TimerBControl =	$dc0f
.const CIA2InterruptControl =	$dd0d
.const CIA2TimerAControl =	$dd0e
.const CIA2TimerBControl =	$dd0f
.const VIC2InteruptControl =	$d01a
.const VIC2InteruptStatus =	$d019
.var bgColor
//---------------------------------------------------------------------------------------------------------------------
//general scripts...

.function _16bit_nextArgument(arg) {
	.if (arg.getType()==AT_IMMEDIATE) .return CmdArgument(arg.getType(), >arg.getValue())
	.return CmdArgument(arg.getType(),arg.getValue()+1)
}

.pseudocommand mb arg1;arg2 { //move byte
	lda arg1
	sta arg2
}

.pseudocommand mw src;tar { //move word
	lda src
	sta tar

	.if (src.getType() == AT_IZEROPAGEY) {
		iny
		lda src
	} else {
		lda _16bit_nextArgument(src)
	}

	.if (tar.getType() == AT_IZEROPAGEY) {
		.if (src.getType() != AT_IZEROPAGEY) iny
		sta tar
	} else {
		sta _16bit_nextArgument(tar)
	}
}
//---------------------------------------------------------------------------------------------------------------------
//scripting for png import...

.function getC64Color(xPos, yPos, pic, rgb2c64) {
	.if (multiColorMode) .eval xPos = xPos*2
	.var rgb = pic.getPixel(xPos, yPos+1)
	.var c64Color = rgb2c64.get(rgb)
	.return c64Color
}

.var charWidth = 8
.var numBlockColors = 2
.if (multiColorMode) {
	.eval charWidth = 4
	.eval numBlockColors = 3
}
	
.function getBlockColors(chrX, chrY, pic, rgb2c64) {
	.var colorCounts = List()
	.for (var i=0; i<16; i++) .eval colorCounts.add(0)
	.for (var pixY=0; pixY<8; pixY++) {
	.for (var pixX=0; pixX<charWidth; pixX++) {
		.var c64Color = getC64Color(chrX*charWidth + pixX, chrY*8 + pixY, pic, rgb2c64)
		.eval colorCounts.set(c64Color, colorCounts.get(c64Color) + 1)
	}}
	.if (multiColorMode) .eval colorCounts.set(bgColor,0)
	.for (var i=0; i<16; i++) .eval colorCounts.set(i, [colorCounts.get(i) << 4] | i)
	.eval colorCounts.sort()
	.eval colorCounts.reverse()
	.var blockColors = List()
	.for (var i=0; i<16; i++) .eval blockColors.add(0)
	.for (var i=0; i<numBlockColors; i++) {
		.var c64Color = colorCounts.get(i) & $0f
		.eval blockColors.set(c64Color, i+1)
	}
	.return blockColors
}

.function getBlock(chrX, chrY, pic, rgb2c64) {
	.var blockColors = getBlockColors(chrX, chrY, pic, rgb2c64)
	.var blockData = List()
	.for (var pixY=0; pixY<8; pixY++) {
		.var bitmapByte = 0
	.for (var pixX=0; pixX<charWidth; pixX++) {
		.var c64Color = getC64Color(chrX*charWidth + pixX, chrY*8 + pixY, pic, rgb2c64)
		.var multiColor = blockColors.get(c64Color)
		.if (multiColorMode) .eval bitmapByte = bitmapByte | [multiColor << [6 - pixX*2]]
		.if (!multiColorMode) .eval bitmapByte = bitmapByte | [[[multiColor-1]^1] << [7 - pixX]]
	}
		.eval blockData.add(bitmapByte)
	}
	.for (var multiColor=1; multiColor<4; multiColor++) {
		.var c64Color = 0
		.for (var i=1; i<16; i++) {
			.if (blockColors.get(i) == multiColor) .eval c64Color = i
		}
		.eval blockData.add(c64Color)
	}
	.return blockData
}

.var bitmapData = List()
.var screenData = List()
.var d800Data = List()

.function parseDoublePic(pic, rgb2c64) {
	.for (var picNo=0; picNo<2; picNo++) {
	.for (var chrY=0; chrY<25; chrY++) {
	.for (var chrX=0; chrX<40; chrX++) {
		.var block = getBlock(chrX+picNo*40, chrY, pic, rgb2c64)
		.for (var i=0; i<8; i++) .eval bitmapData.add(block.get(i))
		.var scrColor = [block.get(8) << 4] | [block.get(9) & $f]
		.eval screenData.add(scrColor)
		.if (multiColorMode) .eval d800Data.add(block.get(10))
	}}}
}

.function initPalette(pngPic) {
	.var rgb2c64 = Hashtable()
	.for (var i=0; i<16; i++) {
		.var xPos = i
		.if (multiColorMode) .eval xPos = i*2
		.var rgb = pngPic.getPixel(xPos,0)
		.eval rgb2c64.put(rgb, i)
	}
	.var bgRgb = pngPic.getPixel(32,0)
	.eval bgColor = rgb2c64.get(bgRgb)
	.if (borderColor == -1) .eval borderColor = bgColor
	.return rgb2c64
}

.if (importMode == PNG_MODE) {
	.var pngPic = LoadPicture("pic.png")
	.var rgb2c64 = initPalette(pngPic)
	.eval parseDoublePic(pngPic, rgb2c64)
}
//---------------------------------------------------------------------------------------------------------------------
//scripting for c64 file import...

.const KOALA_PRG = "Bitmap=$0002, Screen=$1f42, D800=$232a, BackgroundColor=$2712"
.const KOALA_P00 = "Bitmap=$001c, Screen=$1f5c, D800=$2344, BackgroundColor=$272c"
.const HIRES_PRG = "Screen=$0002, Bitmap=$0402"
.const HIRES_P00 = "Screen=$001c, Bitmap=$041c"
.var c64Pics = List()
.if (importMode == C64_MODE) {
	.if (multiColorMode && c64FileType == "prg") {
		.eval c64Pics.add(LoadBinary("pic0.prg", KOALA_PRG))
		.eval c64Pics.add(LoadBinary("pic1.prg", KOALA_PRG))	
	}
	.if (multiColorMode && c64FileType == "p00") {
		.eval c64Pics.add(LoadBinary("pic0.p00", KOALA_P00))
		.eval c64Pics.add(LoadBinary("pic1.p00", KOALA_P00))	
	}
	.if (!multiColorMode && c64FileType == "prg") {
		.eval c64Pics.add(LoadBinary("pic0.prg", HIRES_PRG))
		.eval c64Pics.add(LoadBinary("pic1.prg", HIRES_PRG))	
	}
	.if (!multiColorMode && c64FileType == "p00") {
		.eval c64Pics.add(LoadBinary("pic0.p00", HIRES_P00))
		.eval c64Pics.add(LoadBinary("pic1.p00", HIRES_P00))
	}
	.if (multiColorMode) .eval bgColor = c64Pics.get(0).getBackgroundColor()
	.if (!multiColorMode) .eval bgColor = 0
	.if (borderColor == -1) .eval borderColor = bgColor
}
//---------------------------------------------------------------------------------------------------------------------
//generate look-up tables with bitmap data...

.pc = bitmapLut "bitmapLut"
.for (var yPos=0; yPos<200; yPos++) {
	.for (var pic=0; pic<2; pic++) {
		.for (var xPos=0; xPos<40; xPos++) {
			.if (importMode == C64_MODE) {
				.by c64Pics.get(pic).getBitmap([yPos>>3]*$140 + [yPos&7] + xPos*8)
			}
			.if (importMode == PNG_MODE) {
				.by bitmapData.get([yPos>>3]*$140 + [yPos&7] + xPos*8 + pic*8000)
			}
		}
	}
}

.pc = screenLut "screenLut"
.for (var yPos=0; yPos<25; yPos++) {
	.for (var pic=0; pic<2; pic++) {
		.for (var xPos=0; xPos<40; xPos++) {
			.if (importMode == C64_MODE) {
				.by c64Pics.get(pic).getScreen(yPos*40 + xPos)
			}
			.if (importMode == PNG_MODE) {
				.by screenData.get(yPos*40 + xPos + pic*1000)
			}
		}
	}
}

.if (multiColorMode) {
.pc = d800Lut "d800Lut"
.for (var yPos=0; yPos<25; yPos++) {
	.for (var pic=0; pic<2; pic++) {
		.for (var xPos=0; xPos<40; xPos++) {
			.if (importMode == C64_MODE) {
				.by c64Pics.get(pic).getD800(yPos*40 + xPos)
			}
			.if (importMode == PNG_MODE) {
				.by d800Data.get(yPos*40 + xPos + pic*1000)
			}
		}
	}
}
}
//---------------------------------------------------------------------------------------------------------------------
.pc = basic "basic"
:BasicUpstart(main)

.var sineValues = List()
.for (var i=0; i<sineLength; i++) {
	.var val = sineAmp/2 * sin(i/[sineLength/2/PI])
	.eval val = sineAmp/2 + val * 0.999999999
	.eval sineValues.add(floor(val))
}

.pc = sineLo "sineLo"
	.var d016mc = $00
	.if (multiColorMode) .eval d016mc = $10
	.fill sineLength, [sineValues.get(i) & 7] | d016mc

.pc = sineHi "sineHi"
	.fill sineLength, sineValues.get(i) >> 3
//---------------------------------------------------------------------------------------------------------------------
.pc = main "main"
	sei
	cld
	ldx #$ff
	txs
	jsr init
	cli
//---------------------------------------------------------------------------------------------------------------------
{
mainLoop:
!:	lda topIRQDone
	beq !-
	:mb #0; topIRQDone
	
	lda $d011
	bpl *-3
	inc border

	jsr setScrollParams
	.if (multiColorMode) jsr updateD800
	jsr updateBitmap
	jsr incCnt
	
	:mb #0; border
	jmp mainLoop
}
//---------------------------------------------------------------------------------------------------------------------
.align $100
topIrq:
	//stabilize raster with double irq
	
	//@ line 45
	pha
	txa
	pha
	tya
	pha

	inc topIRQDone

	:mw #irq2; $fffe
	inc $d012
	
	:mb #1; VIC2InteruptStatus	//ack raster interupt

	tsx
	cli
	//these nops never really finish due to the raster IRQ triggering again
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
//---------------------------------------------------------------------------------------------------------------------
irq2:
	//@ line 46
	txs

	ldx #9
!:	dex
	bne !-

	//final cycle wobble check
	lda #irqLine+1
	cmp $d012
	beq *+2

	//the raster is now stable! \o/

	//@ line 47
	:mb #$31; $d011

	//waste more cycles
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop

	//still @ line 47
	
	lda dmaDelay
	lsr 	//divide by 2 to get the number of nops to skip
	sta branch+1
	clv 	//force branch always

	//@ line 48

	bcc branch	//1 cycle extra delay depending on the least significant bit of the x offset
branch:	bvc *	//branch somewhere into the nops depending on the x offset position
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop
	nop

	//show raster position
	inc border
	dec border

	//do the VSP by tweaking d011 at the correct time
	lda #$3b
	dec $d011
	inc $d011
	sta $d011

	ldx extraScreenOn
	:mb d018s,x; $d018
	:mb dd00s,x; $dd00
	:mb d16; $d016
		
	//restart the IRQ chain
	:mw #topIrq; $fffe
	:mb #irqLine; $d012
	:mb #1; VIC2InteruptStatus	//ack raster interupt

	pla
	tay
	pla
	tax
	pla
interruptReturn:
	rti

d018s:	.by $38,$80
dd00s:	.by $95,$94
extraScreenOn:	.by 1,1
topIRQDone:	.by 0
//---------------------------------------------------------------------------------------------------------------------
incCnt:
	inc cnt+0
	bne !+
	inc cnt+1
!:	lda cnt+0
	cmp #<sineLength
	bne !+
	lda cnt+1
	cmp #>sineLength
	bne !+
	:mw #0; cnt
!:	rts

cnt:	.wo sineLength/4  //start to the left
//---------------------------------------------------------------------------------------------------------------------
setScrollParams:
	:mb #0; pnt0+0
	lda cnt+1
	clc
	adc #>sineLo
	sta pnt0+1
	
	ldy cnt+0
	:mb (pnt0),y; d16
	
	lda cnt+1
	clc
	adc #>sineHi
	sta pnt0+1
	
	ldx #0
	lda (pnt0),y
	cmp xPosChr
	beq !+
	ldx #1
	cmp xPosChr
	bpl !+
	ldx #-1
!:	sta xPosChr
	stx dir

	ldy #0
	lda #39
	sec
	sbc xPosChr
	bcs !+
	adc #40
	iny
!:	sta dmaDelay
	sty extraScreenOn
	
	rts
//---------------------------------------------------------------------------------------------------------------------
updateD800:
.if (multiColorMode) {
	ldy extraScreenOn
	cpy extraScreenOn+1
	beq !+
	cpy #1
	beq extra
	jsr moveD800Normal
	jmp !+
extra:	jsr moveD800Extra
!:
	:mb extraScreenOn; extraScreenOn+1
	rts
}
//---------------------------------------------------------------------------------------------------------------------
updateBitmap:
{	
	lda dir
	bne !+
	//no char-pos change
	rts
!:
	lda extraScreenOn
	beq !+
	//no bitmap update needed for extra screen
	rts
!:
	lda xPosChr
	ldx dir
	bmi !+
	clc
	adc #39
!:	sta srcPos

	lda #81
	sec
	sbc srcPos
	sta srcPos
	tax
	
	lda #40
	ldy dir
	bpl !+
	lda #79
!:	sec
	sbc xPosChr
	sta destPos
	tay

.for (var i=0; i<24; i++) {
	lda screenLut-1 + i*80,x
	sta screen + i*40,y
	lda d800Lut-1 + i*80,x
	sta $d800 + i*40,y
}

	//special case for lowest line, which needs to wrap to top of screen when it scrolls far enough
	cpy #64
	bpl wrap
normal:
	lda screenLut-1 + 24*80,x
	sta screen + 24*40,y
	lda d800Lut-1 + 24*80,x
	sta $d800 + 24*40,y
	jmp done
wrap:	
	lda screenLut-1 + 24*80,x
	sta screen-$400 + 24*40,y
	lda d800Lut-1 + 24*80,x
	sta $d800-$400 + 24*40,y
done:	
	
	:mb destPos; destPosBitmap+0
	lda #0
	asl destPosBitmap+0
	rol
	asl destPosBitmap+0
	rol
	asl destPosBitmap+0
	rol
	sta destPosBitmap+1
	
	ldy destPosBitmap+0
	lda destPosBitmap+1
	bne !+
	jmp storeBitmap0
!:	cmp #1
	bne !+
	jmp storeBitmap1
!:	jmp storeBitmap2
}
//---------------------------------------------------------------------------------------------------------------------
.macro storeBitmap(offset) {
	.for (var i=0; i<200; i++) {
		lda bitmapLut - 1 + i*80,x
		.var target = bitmap + offset + [i&7] + [[i>>3]*$140]
		.if (offset == $200 && i >= 192) .eval target = target - $2000 //wrapping
		sta target,y
	}
	rts
}
storeBitmap0:	:storeBitmap($000)
storeBitmap1:	:storeBitmap($100)
storeBitmap2:	:storeBitmap($200)
//---------------------------------------------------------------------------------------------------------------------
//move d800 data when switching between normal/special bitmap screen...
.macro moveD800(srcOffset, tarOffset) {
	.for (var yPos=0; yPos<25; yPos++) {
		.if (yPos < 24) {
				ldx #9
			!:
			.for (var xPos=0; xPos<40; xPos=xPos+10) {
				lda d800Lut + xPos + yPos*80 + srcOffset,x
				sta $d800 + [[xPos + yPos*40 + tarOffset] & $3ff],x
			}
				dex
				bpl !-
		} else {
			//avoid loops for lowest line to make it wrappable...
			.for (var xPos=0; xPos<40; xPos++) {
				lda d800Lut + xPos + yPos*80 + srcOffset
				sta $d800 + [[xPos + yPos*40 + tarOffset] & $3ff]
			}
		}
	}
	rts
}
moveD800Normal:	.if (multiColorMode) :moveD800($02,$01)
moveD800Extra:	.if (multiColorMode) :moveD800($00,$27)
//---------------------------------------------------------------------------------------------------------------------
init:
	:mb #$0b; $d011
	:mb #$00; $d015
	:mb #borderColor; $d020
	:mb #bgColor; $d021
	
	jsr clearInterrupts
	jsr initGfx
	jsr setScrollParams
	jsr initInterrupts
	
	rts
//---------------------------------------------------------------------------------------------------------------------
clearInterrupts:
	:mb #ProcessorPortDDRDefault; $00
	:mb #ProcessorPortAllRAMWithIO; $01
	// Clear all CIA to known state, interrupts off.
	lda #$7f
	sta CIA1InterruptControl
	sta CIA2InterruptControl
	lda #0
	sta VIC2InteruptControl
	sta CIA1TimerAControl
	sta CIA1TimerBControl
	sta CIA2TimerAControl
	sta CIA2TimerBControl
	
	// Ack any interrupts that might have happened from the CIAs
	lda CIA1InterruptControl
	lda CIA2InterruptControl
	// Ack any interrupts that have happened from the VIC2
	:mb #$ff; VIC2InteruptStatus
	
	// Setup kernal and user mode IRQ vectors to point to a blank routine
	:mw #interruptReturn; $fffe
	:mw #interruptReturn; $fffa
	
	rts
//---------------------------------------------------------------------------------------------------------------------
initInterrupts:
	// Setup raster IRQ
	:mw #topIrq; $fffe
	:mb #1; VIC2InteruptControl
	:mb #irqLine; $d012
	:mb #$3b; $d011

	// Ack any interrupts that might have happened from the CIAs
	lda CIA1InterruptControl
	lda CIA2InterruptControl
	// Ack any interrupts that have happened from the VIC2
	:mb #$ff; VIC2InteruptStatus
	
	rts
//---------------------------------------------------------------------------------------------------------------------
initGfx:
	//init bitmap screens, color screens and d800
	
	:mw #bitmapLut+2; source
	:mw #$08; target
	:mb #>bitmap; target+2
	jsr initBitmap
	
	:mw #screenLut+2; source
	:mw #$01; target
	:mb #>screen; target+2
	jsr initScreen
	
	.if (multiColorMode) jsr moveD800Extra
	
	:mb #$34; $01
	
	:mw #bitmapLut; source
	:mw #$138; target
	:mb #>bitmap2; target+2
	jsr initBitmap
	
	:mw #screenLut; source
	:mw #$27; target
	:mb #>screen2; target+2
	jsr initScreen
	
	:mb #$35; $01
	
	rts
//---------------------------------------------------------------------------------------------------------------------
initBitmap:
{
	:mb #0; yPos
yLoop:
	:mw source; pnt0
	
	:mb target+0; pnt1+0
	lda target+1
	ora target+2
	sta pnt1+1
	
	:mb #0; xPos
xLoop:
	ldy #0
	:mb (pnt0),y; (pnt1),y
	
	inc pnt0+0
	bne !+
	inc pnt0+1
!:
	lda #8
	clc
	adc pnt1+0
	sta pnt1+0
	lda pnt1+1
	adc #$00
	and #$1f
	ora target+2
	sta pnt1+1

	inc xPos
	lda xPos
	cmp #40
	bne xLoop

	lda #80
	clc
	adc source+0
	sta source+0
	bcc !+
	inc source+1
!:	
	lda #1
	clc
	adc target+0
	sta target+0
	bcc !+
	inc target+1
!:	
	lda yPos
	and #$07
	cmp #$07
	bne !+
	
	lda #<$138
	clc
	adc target+0
	sta target+0
	lda #>$138
	adc target+1
	and #$1f
	sta target+1
!:
	inc yPos
	lda yPos
	cmp #200
	beq !+
	jmp yLoop
!:
	rts
}
//---------------------------------------------------------------------------------------------------------------------
initScreen:
{
	:mb #0; yPos
yLoop:
	:mw source; pnt0
	
	:mb target+0; pnt1+0
	lda target+1
	ora target+2
	sta pnt1+1
	
	:mb #0; xPos
xLoop:
	ldy #0
	:mb (pnt0),y; (pnt1),y
	
	inc pnt0+0
	bne !+
	inc pnt0+1
!:
	lda #1
	clc
	adc pnt1+0
	sta pnt1+0
	lda pnt1+1
	adc #$00
	and #$03
	ora target+2
	sta pnt1+1

	inc xPos
	lda xPos
	cmp #40
	bne xLoop

	lda #80
	clc
	adc source+0
	sta source+0
	bcc !+
	inc source+1
!:	
	lda #40
	clc
	adc target+0
	sta target+0
	bcc !+
	inc target+1
!:
	inc yPos
	lda yPos
	cmp #25
	beq !+
	jmp yLoop
!:
	rts
}
//---------------------------------------------------------------------------------------------------------------------
</code>