org $800

REG_NEWVID = $c029
FB_BASE	= $e12000

	clc
	xce

	lda #$c1
	sta REG_NEWVID

	rep #$30	; accum/index 16bit
	lda #$0000
	ldx #$0000
fillrest
	stal $e19d00,x
	inx
	inx
	cpx #$100
	bne fillrest
	
	lda #$0000
cmap	pha
	sta 0
	asl
	tax	; offset = i * 2
	asl
	asl
	asl
	ora 0
	sta 0
	xba
	ora 0
	stal $e19e00,x
	pla
	inc
	cmp #$000f
	bne cmap

YVAL	= 0
TMPVAL	= 1

	sep #$20	; accum 8bit
	ldx #0		; fb index
	stz YVAL
yloop	ldy #0000	; column/2 on Y reg
xloop	tya
	asl
	and #$0f
	sta TMPVAL	; save first pixel X coordinate
	inc		; increment by 1 for the next pixel
	eor YVAL
	asl		; move next pixel value to high nibble
	asl
	asl
	asl
	ora TMPVAL	; first pixel X -> low nibble
	eor YVAL

	stal FB_BASE, x	; write the pixel pair
	inx
	iny
	cpy #160
	bne xloop
	inc YVAL
	lda YVAL
	cmp #200
	bne yloop

infloop	bra infloop

	; vi:ft=asm_ca65