keen: make more things use tilemap lookup

only saves handful of cycles it seems

games/keen/Makefile

@@ -69,7 +69,7 @@ level1.o:	level1.s zp.inc hardware.inc \
 	graphics/keen_graphics.inc sprites/keen_sprites.inc \
 	maps/level1_map.lzsa \
 	status_bar.s draw_keen.s move_keen.s gr_putsprite_crop.s \
-	draw_tilemap.s \
+	draw_tilemap.s tilemap_lookup.s \
 	level1_sfx.s longer_sound.s \
 	keyboard.s handle_laser.s
 	ca65 -o level1.o level1.s -l level1.lst

games/keen/draw_tilemap.s

@@ -4,62 +4,64 @@
 	; tilemap is 20x12 grid with 2x4 (well, 2x2) tiles
 
 draw_tilemap:
-	ldy	#0			; current screen Ypos to draw at
+	ldx	#0		; offset in current tilemap		; 2
-	sty	TILEY			; (we draw two at a time as lores
+	stx	TILEMAP_OFFSET	;					; 3
-					;	is two blocks per byte)
 
-	ldx	#0			; offset in current tilemap
+;	ldy	#0		; current screen Ypos to draw at	; 2
-	stx	TILEMAP_OFFSET		;
+	stx	TILEY		; (we draw two at a time as lores	; 3
+				;	is two blocks per byte)
 
-	lda	#0			; init odd/even
+
-	sta	TILE_ODD		; (tiles are two rows tall)
+
+;	lda	#0		; init odd/even				; 2
+	stx	TILE_ODD	; (tiles are two rows tall)		; 3
 
 tilemap_outer_loop:
-	ldy	TILEY			; setup output pointer to current Ypos
+	ldy	TILEY		; setup output pointer to current Ypos	; 3
 
-	lda	gr_offsets,Y		; get address of start of row
+	lda	gr_offsets,Y	; get address of start of row		; 4+
-	sta	GBASL
+	sta	GBASL							; 3
-	lda	gr_offsets+1,Y
+	lda	gr_offsets+1,Y						; 4+
-	clc
+	clc								; 2
-	adc	DRAW_PAGE		; adjust for page
+	adc	DRAW_PAGE	; adjust for page			; 3
-	sta	GBASH
+	sta	GBASH							; 3
 
 
-	ldy	#0			; draw row from 0..39
+	ldy	#0		; draw row from 0..39			; 2
-					; might be faster to count backwards
+				; might be faster to count backwards
-					; but would have to adjust a lot
+				; but would have to adjust a lot
 
 tilemap_loop:
-	ldx	TILEMAP_OFFSET		; get actual tile number
+	ldx	TILEMAP_OFFSET	; get actual tile number		; 3
-	lda	small_tilemap,X		; from tilemap
+	lda	small_tilemap,X	; from tilemap				; 4
 
-	asl			; *4	; point to tile to draw (4 bytes each)
+	asl		; *4	; point to tile to draw (4 bytes each)	; 2
-	asl
+	asl								; 2
-	tax
+	tax								; 2
 
-	lda	TILE_ODD		; check to see if top or bottom
+	lda	TILE_ODD	; check to see if top or bottom		; 3
-	beq	not_odd_line
+	beq	not_odd_line						; 2/3
-	inx				; point to bottom half of tile
+	inx			; point to bottom half of tile		; 2
-	inx
+	inx								; 2
 not_odd_line:
 
 	; draw two blocks
 	; note we don't handle transparency in the keen engine
 
-	lda	tiles,X
+	lda	tiles,X							; 4
-	sta	(GBASL),Y		; draw upper right
+	sta	(GBASL),Y	; draw upper right			; 6
 
-	iny
+	iny								; 2
 
-	lda	tiles+1,X
+	lda	tiles+1,X						; 4
-	sta	(GBASL),Y		; draw upper left
+	sta	(GBASL),Y		; draw upper left		; 6
 
-	iny
+	iny								; 2
 
-	inc	TILEMAP_OFFSET		; point to next tile
+	inc	TILEMAP_OFFSET		; point to next tile		; 5
 
-	cpy	#40			; until done
+	cpy	#40			; until done			; 2
-	bne	tilemap_loop
+	bne	tilemap_loop						; 2/3
 
 
 
@@ -126,22 +128,35 @@ copy_tilemap_subset:
 	lda	#0
 	sta	tilemap_count_smc+1
 
+	; original worse case: 23 cycles
+	; lookup table: 19 cycles
+
 	; set start
-	lda	TILEMAP_Y
+
-	lsr
+	ldx	TILEMAP_Y						; 3
+	lda	tilemap_lookup_high,X					; 4
+	sta	cptl1_smc+2	; set proper row in big tilemap		; 4
+	lda	tilemap_lookup_low,X					; 4
+	sta	cptl1_smc+1	; set proper row in big tilemap		; 4
+
+
+	; set start
+;	lda	TILEMAP_Y						; 3
+;	lsr								; 2
 
 	; set odd/even
-	ldx	#0
+;	ldx	#0							; 2
-	bcc	skip_odd_row
+;	bcc	skip_odd_row						; 2/3
-	ldx	#$80
+;	ldx	#$80							; 2
-skip_odd_row:
+;skip_odd_row:
-	stx	cptl1_smc+1
+;	stx	cptl1_smc+1						; 4
 
-	clc				; set start
+;	clc			; set start				; 2
-	adc	#>big_tilemap		; each even row is a page, so adding
+;	adc	#>big_tilemap	; each even row is a page, so adding	; 2
-					; Y to top byte is indexing to row
+				; Y to top byte is indexing to row
+
+;	sta	cptl1_smc+2	; set proper row in big tilemap		; 4
 
-	sta	cptl1_smc+2		; set proper row in big tilemap
 
 
 	lda	#<small_tilemap
@@ -153,14 +168,15 @@ cp_tilemap_outer_loop:
 	ldy	#0
 cp_tilemap_inner_loop:
 
+	; FIXME: make cptl1 take into account X offset and use one index?
 	; TODO: optimize, totally unroll?
 
 cptl1_smc:
-	lda	$9400,X
+	lda	$9400,X							; 4
 cptl2_smc:
-	sta	$BC00,Y
+	sta	$BC00,Y							; 5
-	iny
+	iny								; 2
-	inx
+	inx								; 2
 	cpy	#TILEMAP_X_COPY_SIZE
 	bne	cp_tilemap_inner_loop
 

games/keen/level1.s

@@ -302,5 +302,7 @@ level1_levelover:
 
 	.include	"random16.s"
 
+	.include	"tilemap_lookup.s"
+
 level1_data_zx02:
 	.incbin		"maps/level1_map.zx02"