keen: make more things use tilemap lookup

only saves handful of cycles it seems
This commit is contained in:
Vince Weaver 2024-04-14 22:35:37 -04:00
parent ed5053bb1e
commit 0ec8efc1be
3 changed files with 69 additions and 51 deletions

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@ -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

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@ -4,62 +4,64 @@
; tilemap is 20x12 grid with 2x4 (well, 2x2) tiles
draw_tilemap:
ldy #0 ; current screen Ypos to draw at
sty TILEY ; (we draw two at a time as lores
ldx #0 ; offset in current tilemap ; 2
stx TILEMAP_OFFSET ; ; 3
; ldy #0 ; current screen Ypos to draw at ; 2
stx TILEY ; (we draw two at a time as lores ; 3
; is two blocks per byte)
ldx #0 ; offset in current tilemap
stx TILEMAP_OFFSET ;
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
sta GBASL
lda gr_offsets+1,Y
clc
adc DRAW_PAGE ; adjust for page
sta GBASH
lda gr_offsets,Y ; get address of start of row ; 4+
sta GBASL ; 3
lda gr_offsets+1,Y ; 4+
clc ; 2
adc DRAW_PAGE ; adjust for page ; 3
sta GBASH ; 3
ldy #0 ; draw row from 0..39
ldy #0 ; draw row from 0..39 ; 2
; might be faster to count backwards
; but would have to adjust a lot
tilemap_loop:
ldx TILEMAP_OFFSET ; get actual tile number
lda small_tilemap,X ; from tilemap
ldx TILEMAP_OFFSET ; get actual tile number ; 3
lda small_tilemap,X ; from tilemap ; 4
asl ; *4 ; point to tile to draw (4 bytes each)
asl
tax
asl ; *4 ; point to tile to draw (4 bytes each) ; 2
asl ; 2
tax ; 2
lda TILE_ODD ; check to see if top or bottom
beq not_odd_line
inx ; point to bottom half of tile
inx
lda TILE_ODD ; check to see if top or bottom ; 3
beq not_odd_line ; 2/3
inx ; point to bottom half of tile ; 2
inx ; 2
not_odd_line:
; draw two blocks
; note we don't handle transparency in the keen engine
lda tiles,X
sta (GBASL),Y ; draw upper right
lda tiles,X ; 4
sta (GBASL),Y ; draw upper right ; 6
iny
iny ; 2
lda tiles+1,X
sta (GBASL),Y ; draw upper left
lda tiles+1,X ; 4
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
bne tilemap_loop
cpy #40 ; until done ; 2
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
bcc skip_odd_row
ldx #$80
skip_odd_row:
stx cptl1_smc+1
; ldx #0 ; 2
; bcc skip_odd_row ; 2/3
; ldx #$80 ; 2
;skip_odd_row:
; stx cptl1_smc+1 ; 4
clc ; set start
adc #>big_tilemap ; each even row is a page, so adding
; clc ; set start ; 2
; adc #>big_tilemap ; each even row is a page, so adding ; 2
; Y to top byte is indexing to row
sta cptl1_smc+2 ; set proper row in big tilemap
; sta cptl1_smc+2 ; set proper row in big tilemap ; 4
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
iny
inx
sta $BC00,Y ; 5
iny ; 2
inx ; 2
cpy #TILEMAP_X_COPY_SIZE
bne cp_tilemap_inner_loop

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