;r0 = VDP address
	;r1 = current color
	;r2 = color increment
	;r3 = target line
	;r4 = screen bottom
	;r5 = scratch
	;r6 = right edge
	;r7 = counter
	ldim 248, r4
	ldimh 0, r4
	;320 == $140
	ldim $40, r6
	ldimh 1, r6
top
	ldim 0, r0
	ldimh $FF, r0
	ldim 0, r1
	ldim 1, r2
	ldim 8, r3
	ldim 16, r7
	
linestart
	outi 14, r0
waitline
	ini $C, r5
	cmp r5, r3
	bne waitline
	
waithblank
	ini $D, r5
	cmp r5, r6
	bgr waithblank
	
	outi 15, r1
	add r2, r1, r1
	addi 4, r3
	
	addi -1, r7
	bne normal
	ldim 16, r7
	;TODO: replace with lsli once it works in the assembler
	add r2, r2, r2
	add r2, r2, r2
	add r2, r2, r2
	add r2, r2, r2
	ldim 0, r1
	
normal
	
	cmp r3, r4
	beq top
	bra linestart