xmas2019: update tree

xmas_2019/Makefile

@@ -6,11 +6,22 @@ PNG_TO_40x48D = ../gr-utils/png_to_40x48d
 
 all:	xmas2019.dsk
 
-xmas2019.dsk:	SNOW HELLO
+xmas2019.dsk:	SNOW TREE HELLO
 	cp empty.dsk xmas2019.dsk
 	$(DOS33) -y xmas2019.dsk BSAVE -a 0x1000 SNOW
+	$(DOS33) -y xmas2019.dsk BSAVE -a 0x1000 TREE
 	$(DOS33) -y xmas2019.dsk SAVE A HELLO
 
+####
+
+TREE:	tree.o
+	ld65 -o TREE tree.o -C ../linker_scripts/apple2_1000.inc
+
+tree.o:	tree.s
+#gr_copy.s random16.s fw.s hgr.s delay_a.s \
+#		vapor_lock.s gr_hline.s state_machine.s move_letters.s \
+#		background_final.inc
+	ca65 -o tree.o tree.s -l tree.lst
 
 ####
 

xmas_2019/tree.s

@@ -0,0 +1,144 @@
+; Display awesome tree
+
+; by deater (Vince Weaver) <vince@deater.net>
+
+; Zero Page
+CH		= $24
+CV		= $25
+GBASL		= $26
+GBASH		= $27
+BASL		= $28
+BASH		= $29
+HGR_COLOR	= $E4
+SNOWX		= $F0
+COLOR		= $F1
+
+HGR		= $F3E2
+
+.include	"hardware.inc"
+
+
+	;==================================
+	;==================================
+
+	bit	SET_GR
+	bit	FULLGR
+	bit	LORES
+	bit	PAGE0
+
+
+display_loop:
+
+	;=========================
+	; erase old line
+
+	ldx	#0
+	ldy	which_line_y,X
+	lda	sine_table,Y
+	tay
+	ldx	#0
+	jsr	draw_line
+
+	;==========================
+	; move line
+
+	inc	which_line_y
+	lda	which_line_y
+	and	#$7f
+	sta	which_line_y
+
+
+	;=========================
+	; draw new line
+
+	ldx	#0
+	ldy	which_line_y,X
+	lda	sine_table,Y
+	tay
+	ldx	#$44
+	jsr	draw_line
+
+	lda	#100
+	jsr	WAIT
+
+	jmp	display_loop				; 3
+
+
+	;=================================
+	; draw line
+
+draw_line:
+	tya
+	and	#$1
+	bne	draw_line_odd
+
+draw_line_even:
+	lda	gr_offsets,Y
+	clc
+	adc	#10
+	sta	GBASL
+
+	lda	gr_offsets+1,Y
+	sta	GBASH
+
+	ldy	#0
+	txa
+	and	#$0f
+	sta	COLOR
+line_loop:
+	lda	(GBASL),Y
+	and	#$f0
+	ora	COLOR
+	sta	(GBASL),Y
+	iny
+	cpy	#20
+	bne	line_loop
+
+	rts
+
+
+draw_line_odd:
+	tya
+	and	#$fe
+	tay
+	lda	gr_offsets,Y
+	clc
+	adc	#10
+	sta	GBASL
+
+	lda	gr_offsets+1,Y
+	sta	GBASH
+
+	ldy	#0
+	txa
+	and	#$f0
+	sta	COLOR
+line_loop_odd:
+	lda	(GBASL),Y
+	and	#$0f
+	ora	COLOR
+	sta	(GBASL),Y
+	iny
+	cpy	#20
+	bne	line_loop_odd
+
+	rts
+
+
+gr_offsets:
+	.word	$400,$480,$500,$580,$600,$680,$700,$780
+	.word	$428,$4a8,$528,$5a8,$628,$6a8,$728,$7a8
+	.word	$450,$4d0,$550,$5d0,$650,$6d0,$750,$7d0
+
+which_line_y:
+	.byte 0
+
+sine_table:
+	.byte 23,23,24,25,25,26,27,28,28,29,30,30,31,31,32,33
+	.byte 33,34,34,35,35,35,36,36,36,37,37,37,37,37,37,37
+	.byte 37,37,37,37,37,37,37,37,36,36,36,35,35,35,34,34
+	.byte 33,33,32,31,31,30,30,29,28,28,27,26,25,25,24,23
+	.byte 23,23,22,21,21,20,19,18,18,17,16,16,15,15,14,13
+	.byte 13,12,12,11,11,11,10,10,10, 9, 9, 9, 9, 9, 9, 9
+	.byte  9, 9, 9, 9, 9, 9, 9, 9,10,10,10,11,11,11,12,12
+	.byte 13,13,14,15,15,16,16,17,18,18,19,20,21,21,22,23