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video.asm
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video.asm
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PALETTE_CACHE .rs 32 ; temporary memory for palette, for dimming
; cursors target coordinates
SPRITE_0_X_TARGET .rs 1
SPRITE_1_X_TARGET .rs 1
SPRITE_Y_TARGET .rs 1
; variables for game name drawing
TEXT_DRAW_GAME .rs 2
TEXT_DRAW_ROW .rs 1
SCROLL_LINES .rs 2 ; current scroll line
SCROLL_LINES_MODULO .rs 1 ; current scroll line % 30
LAST_LINE_MODULO .rs 1
LAST_LINE_GAME .rs 2
SCROLL_FINE .rs 1 ; fine scroll position
SCROLL_LINES_TARGET .rs 2 ; scrolling target
STAR_SPAWN_TIMER .rs 1 ; stars spawn timer
STAR_SPAWN_COUNTER .rs 1 ; stars spawn counter
; for build info
CHR_RAM_SIZE .rs 1 ; CHR RAM size 8*2^xKB
LAST_ATTRIBUTE_ADDRESS .rs 1 ; to prevent duplicate writes
SCHEDULE_PRINT_FIRST .rs 1
SCHEDULE_PRINT_LAST .rs 1
; flag to lock scrolling at zero
SCROLL_LOCK .rs 1
; flag that save warning message is active
SAVE_WARNED .rs 1
; constants
CHARS_PER_LINE .equ 32
LINES_PER_SCREEN .equ 15
SPRITE_0_Y .equ SPRITES + 0
SPRITE_0_TILE .equ SPRITES + 1
SPRITE_0_ATTR .equ SPRITES + 2
SPRITE_0_X .equ SPRITES + 3
SPRITE_1_Y .equ SPRITES + 4
SPRITE_1_TILE .equ SPRITES + 5
SPRITE_1_ATTR .equ SPRITES + 6
SPRITE_1_X .equ SPRITES + 7
waitblank:
pha
tya
pha
txa
pha
bit PPUSTATUS ; reset vblank bit
.loop:
lda PPUSTATUS ; load A with value at location PPUSTATUS
bpl .loop ; if bit 7 is not set (not VBlank) keep checking
; updating sprites
jsr sprite_dma_copy
lda <SCHEDULE_PRINT_FIRST
beq .first_not_scheduled
jsr print_first_name
lda #0
sta <SCHEDULE_PRINT_FIRST
.first_not_scheduled:
lda <SCHEDULE_PRINT_LAST
beq .last_not_scheduled
jsr print_last_name
lda #0
sta <SCHEDULE_PRINT_LAST
.last_not_scheduled:
jsr scroll_fix
; scrolling
lda <SCROLL_LOCK
bne .skip_scrolling
jsr move_scrolling
.skip_scrolling:
; moving cursors
jsr move_cursors
; reading controller
jsr read_controller
; stars on the background
.if STARS!=0
jsr stars
.endif
pla
tax
pla
tay
pla
rts
waitblank_simple:
pha
bit PPUSTATUS
.loop:
lda PPUSTATUS ; load A with value at location PPUSTATUS
bpl .loop ; if bit 7 is not set (not VBlank) keep checking
pla
rts
waitblank_x:
; for for v-blank X times
cpy #0
bne .loop
rts
.loop:
jsr waitblank
dex
bne .loop
rts
scroll_fix:
pha
tya
pha
; scrolling reset
bit PPUSTATUS
; X coordinate always 0
lda #0
sta PPUSCROLL
ldy <SCROLL_LOCK
beq .need_to_scroll
; scolling is locked
sta PPUSCROLL
ldy #%00001000 ; first nametable
sty PPUCTRL ; set base nametable
jmp .scroll_done
.need_to_scroll:
lda <SCROLL_LINES_MODULO
cmp #LINES_PER_SCREEN
bcc .first_screen
sec
sbc #LINES_PER_SCREEN ; substracting otherwise
ldy #%00001010 ; second nametable
jmp .set_nametable
.first_screen:
ldy #%00001000 ; first nametable
.set_nametable:
sty PPUCTRL ; set base nametable
; calculating Y coordinate
asl A
asl A
asl A
asl A
clc
adc <SCROLL_FINE
sta PPUSCROLL
.scroll_done
pla
tay
pla
rts
scroll_line_down:
lda <SCROLL_LINES
clc
adc #1
sta <SCROLL_LINES
lda <SCROLL_LINES+1
adc #0
sta <SCROLL_LINES+1
inc <SCROLL_LINES_MODULO
lda <SCROLL_LINES_MODULO
cmp #LINES_PER_SCREEN * 2
bcc .modulo_ok
lda #0
sta <SCROLL_LINES_MODULO
.modulo_ok:
lda <LAST_LINE_GAME
clc
adc #1
sta <LAST_LINE_GAME
lda <LAST_LINE_GAME+1
adc #0
sta <LAST_LINE_GAME+1
inc <LAST_LINE_MODULO
lda <LAST_LINE_MODULO
cmp #LINES_PER_SCREEN * 2
bcc .modulo_ok2
lda #0
sta <LAST_LINE_MODULO
.modulo_ok2:
;jsr print_last_name
inc SCHEDULE_PRINT_LAST
rts
scroll_line_up:
lda <SCROLL_LINES
sec
sbc #1
sta <SCROLL_LINES
lda <SCROLL_LINES+1
sbc #0
sta <SCROLL_LINES+1
dec <SCROLL_LINES_MODULO
bpl .modulo_ok
lda #LINES_PER_SCREEN * 2 - 1
sta <SCROLL_LINES_MODULO
.modulo_ok:
lda <LAST_LINE_GAME
sec
sbc #1
sta <LAST_LINE_GAME
lda <LAST_LINE_GAME+1
sbc #0
sta <LAST_LINE_GAME+1
dec <LAST_LINE_MODULO
bpl .modulo_ok2
lda #LINES_PER_SCREEN * 2 - 1
sta <LAST_LINE_MODULO
.modulo_ok2:
;jsr print_first_name
inc SCHEDULE_PRINT_FIRST
rts
screen_wrap_down:
jsr wait_scroll_done
lda #0
sta <SELECTED_GAME
sta <SELECTED_GAME+1
lda #0
sta <SCROLL_LINES_TARGET
sta <SCROLL_LINES_TARGET+1
sta <SCROLL_LINES
sta <SCROLL_LINES+1
sta <LAST_LINE_GAME
sta <LAST_LINE_GAME+1
jsr set_cursor_targets
ldx #LINES_PER_SCREEN
.lines_loop
; draw lines and update screen
jsr waitblank_simple
jsr print_last_name
jsr sprite_dma_copy
jsr scroll_fix
jsr move_cursors
.if STARS!=0
jsr stars
.endif
cpx #0
beq .end
; increment everything
inc <SCROLL_LINES_MODULO
lda <SCROLL_LINES_MODULO
cmp #LINES_PER_SCREEN * 2
bcc .modulo_ok
lda #0
sta <SCROLL_LINES_MODULO
.modulo_ok:
inc <LAST_LINE_MODULO
lda <LAST_LINE_MODULO
cmp #LINES_PER_SCREEN * 2
bcc .modulo_ok2
lda #0
sta <LAST_LINE_MODULO
.modulo_ok2:
inc <LAST_LINE_GAME
; next line?
dex
jmp .lines_loop
.end:
rts
screen_wrap_up:
jsr wait_scroll_done
; some weird math
lda #LOW(GAMES_COUNT - 1)
sta <SELECTED_GAME
lda #HIGH(GAMES_COUNT - 1)
sta <SELECTED_GAME+1
lda #LOW(GAMES_COUNT + 4)
sta <SCROLL_LINES
lda #HIGH(GAMES_COUNT + 4)
sta <SCROLL_LINES+1
lda #LOW(GAMES_COUNT - 11)
sta <SCROLL_LINES_TARGET
lda #HIGH(GAMES_COUNT - 11)
sta <SCROLL_LINES_TARGET+1
lda #LOW(GAMES_COUNT + 4)
sta <LAST_LINE_GAME
lda #HIGH(GAMES_COUNT + 4)
sta <LAST_LINE_GAME+1
jsr set_cursor_targets
ldx #LINES_PER_SCREEN
.lines_loop:
; decrement everything
dec <SCROLL_LINES_MODULO
bpl .modulo_ok
lda #LINES_PER_SCREEN * 2 - 1
sta <SCROLL_LINES_MODULO
.modulo_ok:
dec <LAST_LINE_MODULO
bpl .modulo_ok2
lda #LINES_PER_SCREEN * 2 - 1
sta <LAST_LINE_MODULO
.modulo_ok2:
lda <SCROLL_LINES
sec
sbc #1
sta <SCROLL_LINES
lda <SCROLL_LINES+1
sbc #0
sta <SCROLL_LINES+1
; draw lines and update screen
jsr waitblank_simple
jsr print_first_name
jsr sprite_dma_copy
jsr scroll_fix
jsr move_cursors
.if STARS!=0
jsr stars
.endif
; next line?
dex
bne .lines_loop
rts
load_base_chr:
; loading CHR
lda #BANK(chr_data) / 2 ; bank with CHR
jsr select_prg_bank
lda #LOW(chr_data)
sta COPY_SOURCE_ADDR
lda #HIGH(chr_data)
sta COPY_SOURCE_ADDR+1
jsr load_chr
rts
preload_palette:
; loading palette into palette cache
ldy #0
.loop:
lda [COPY_SOURCE_ADDR], y
sta PALETTE_CACHE, y
iny
cpy #32
bne .loop
rts
preload_base_palette:
; loading palette into palette cache
lda #BANK(tilepal) / 2 ; bank with palette
jsr select_prg_bank
lda #LOW(tilepal)
sta COPY_SOURCE_ADDR
lda #HIGH(tilepal)
sta COPY_SOURCE_ADDR+1
jsr preload_palette
rts
; loading palette from cache to PPU
load_palette:
jsr waitblank_simple
lda #LOW(PALETTE_CACHE)
sta <COPY_SOURCE_ADDR
lda #HIGH(PALETTE_CACHE)
sta <COPY_SOURCE_ADDR+1
lda #$3F
sta $2006
lda #$00
sta $2006
ldy #$00
ldx #32
.loop:
lda [COPY_SOURCE_ADDR], y
sta $2007
iny
dex
bne .loop
jsr scroll_fix
rts
;load_base_pal:
; loading palette into $3F00 of PPU
;lda #$3F
;sta PPUADDR
;lda #$00
;sta PPUADDR
;ldx #$00
;.loop:
;lda tilepal, x
;sta PPUDATA
;inx
;cpx #32
;bne .loop
;rts
dim:
; dimming preloaded palette
ldx #0
.loop:
lda PALETTE_CACHE, x
sec
sbc #$10
bpl .not_minus
lda #$1D
.not_minus:
cmp #$0D
bne .not_very_black
lda #$1D
.not_very_black:
sta PALETTE_CACHE, x
inx
cpx #32
bne .loop
rts
; dimming base palette in
dim_base_palette_in:
;lda BUTTONS
;bne .done ; skip if any button pressed
.if ENABLE_DIM_IN!=0
.if DIM_IN_DELAY <= 0
.fail DIM_IN_DELAY must be > 0
.endif
jsr preload_base_palette
jsr dim
jsr dim
jsr dim
jsr load_palette
ldx #DIM_IN_DELAY
jsr waitblank_x
;lda BUTTONS
;bne .done ; skip if any button pressed
jsr preload_base_palette
jsr dim
jsr dim
jsr load_palette
ldx #DIM_IN_DELAY
jsr waitblank_x
;lda BUTTONS
;bne .done ; skip if any button pressed
jsr preload_base_palette
jsr dim
jsr load_palette
ldx #DIM_IN_DELAY
jsr waitblank_x
.endif
.done:
jsr preload_base_palette
jsr load_palette
jsr waitblank
rts
; dimming base palette out in
dim_base_palette_out:
.if ENABLE_DIM_OUT!=0
.if DIM_OUT_DELAY <= 0
.fail DIM_OUT_DELAY must be > 0
.endif
jsr preload_base_palette
jsr dim
jsr load_palette
ldx #DIM_OUT_DELAY
jsr waitblank_x
jsr preload_base_palette
jsr dim
jsr dim
jsr load_palette
ldx #DIM_OUT_DELAY
jsr waitblank_x
jsr preload_base_palette
jsr dim
jsr dim
jsr dim
jsr load_palette
ldx #DIM_OUT_DELAY
jsr waitblank_x
.endif
jsr load_black
jsr waitblank
rts
; loading empty black palette into $3F00 of PPU
load_black:
; waiting for vblank
; need even if rendering is disabled
; to prevent lines on black screen
jsr waitblank_simple
lda #$3F
sta PPUADDR
lda #$00
sta PPUADDR
ldx #$00
lda #$3F ; color
.loop:
sta PPUDATA
inx
cpx #32
bne .loop
rts
; nametable cleanup
clear_screen:
lda #$20
sta PPUADDR
lda #$00
sta PPUADDR
lda #$00
ldx #0
ldy #$10
.loop:
sta PPUDATA
inx
bne .loop
dey
bne .loop
rts
; clear all sprites data
clear_sprites:
lda #$FF
ldx #0
.loop:
sta SPRITES, x
inx
bne .loop
rts
; DMA sprites loading
sprite_dma_copy:
pha
lda #0
sta OAMADDR
lda #HIGH(SPRITES)
sta OAMDMA
pla
rts
; loading header (image on the top), first part
draw_header1:
lda #BANK(nametable_header) / 2 ; bank with header
jsr select_prg_bank
ldx #0
ldy #$40
.loop:
lda nametable_header, x
sta PPUDATA
inx
dey
bne .loop
rts
; loading header (image on the top), second part
draw_header2:
lda #BANK(nametable_header) / 2 ; bank with header
jsr select_prg_bank
ldx #$40
ldy #$40
.loop:
lda nametable_header, x
sta PPUDATA
inx
dey
bne .loop
rts
; loading footer (image on the bottom), first part
draw_footer1:
lda #$06
jsr select_prg_bank
ldx #0
ldy #$40
.loop:
lda nametable_footer, x
sta PPUDATA
inx
dey
bne .loop
rts
; loading footer (image on the bottom), second part
draw_footer2:
lda #$06
jsr select_prg_bank
ldx #$40
ldy #$40
.loop:
lda nametable_footer, x
sta PPUDATA
inx
dey
bne .loop
rts
; printing game name on the top
print_first_name:
pha
lda <SCROLL_LINES
sta <TEXT_DRAW_GAME
lda <SCROLL_LINES+1
sta <TEXT_DRAW_GAME+1
lda <SCROLL_LINES_MODULO
sta <TEXT_DRAW_ROW
jsr print_name
pla
rts
; printing game name on the bottom
print_last_name:
pha
lda <LAST_LINE_GAME
sta <TEXT_DRAW_GAME
lda <LAST_LINE_GAME+1
sta <TEXT_DRAW_GAME+1
lda <LAST_LINE_MODULO
sta <TEXT_DRAW_ROW
jsr print_name
pla
rts
print_name:
pha
tya
pha
txa
pha
; when there are not so many games we need offset
.if GAMES_COUNT <= 10
lda TEXT_DRAW_GAME
cmp #2
bcc .padding_end
cmp #(GAMES_COUNT + 2)
beq .padding_footer_1
cmp #(GAMES_COUNT + 3)
beq .padding_footer_2
lda <TEXT_DRAW_ROW
clc
adc #(6 - GAMES_COUNT / 2 - GAMES_COUNT % 2)
sta <TEXT_DRAW_ROW
jmp .padding_end
.padding_footer_1:
lda #13
sta <TEXT_DRAW_ROW
jmp .padding_end
.padding_footer_2:
lda #14
sta <TEXT_DRAW_ROW
.padding_end:
.endif
lda <TEXT_DRAW_ROW
; detecting target nametable and PPU address
cmp #LINES_PER_SCREEN
bcc .first_screen
; second
sec
sbc #LINES_PER_SCREEN
lsr A
lsr A
clc
adc #$2C
bit PPUSTATUS
sta PPUADDR
lda <TEXT_DRAW_ROW
sec
sbc #LINES_PER_SCREEN
asl A
asl A
asl A
asl A
asl A
asl A
sta PPUADDR
jmp .print_start
; first
.first_screen:
lsr A
lsr A
clc
adc #$20
bit PPUSTATUS
sta PPUADDR
lda <TEXT_DRAW_ROW
asl A
asl A
asl A
asl A
asl A
asl A
sta PPUADDR
.print_start:
; is it header lines?
lda <TEXT_DRAW_GAME+1
bne .not_header ; no
lda <TEXT_DRAW_GAME
beq .header1
cmp #1
beq .header2
jmp .not_header
.header1:
jsr draw_header1
jsr set_line_attributes
jmp .end
.header2:
jsr draw_header2
jsr set_line_attributes
jmp .end
.not_header:
; we need to substract 2 from game number
lda <TEXT_DRAW_GAME
sec
sbc #2
; store game number to TMP and TMP+1
sta <TMP
lda <TEXT_DRAW_GAME+1
sbc #0
sta <TMP+1
; is it footer?
lda <TMP+1
cmp #HIGH(GAMES_COUNT)
bne .not_footer_1
lda <TMP
cmp #LOW(GAMES_COUNT)
bne .not_footer_1
jsr draw_footer1
jsr set_line_attributes
jmp .end
.not_footer_1:
lda <TMP+1
cmp #HIGH(GAMES_COUNT + 1)
bne .not_footer_2
lda <TMP
cmp #LOW(GAMES_COUNT + 1)
bne .not_footer_2
jsr draw_footer2
jsr set_line_attributes
jmp .end
.not_footer_2:
lda <TMP
sec
sbc #LOW(GAMES_COUNT)
lda <TMP+1
sbc #HIGH(GAMES_COUNT)
bcs .end
lda <TMP+1
jsr select_prg_bank
lda #LOW(game_names)
clc
adc <TMP
sta <COPY_SOURCE_ADDR
lda #HIGH(game_names)
adc #0
sta <COPY_SOURCE_ADDR+1
; x2 (because address two bytes length)
lda <COPY_SOURCE_ADDR
clc
adc <TMP
sta <COPY_SOURCE_ADDR
lda <COPY_SOURCE_ADDR+1
adc #0
sta <COPY_SOURCE_ADDR+1
ldy #0
lda [COPY_SOURCE_ADDR], y
sta <TMP
iny
lda [COPY_SOURCE_ADDR], y
sta <COPY_SOURCE_ADDR+1
lda <TMP
sta <COPY_SOURCE_ADDR
; spaces on the left
ldx #GAME_NAMES_OFFSET+1
.print_blank:
lda #$00
sta PPUDATA
dex
bne .print_blank
; text
ldx #GAME_NAMES_OFFSET+1
ldy #0
lda #1
.next_char:
cmp #0 ; after zero we are not printing letters but printing spaces
beq .end_of_line
lda [COPY_SOURCE_ADDR], y
.end_of_line:
sta PPUDATA
iny
inx
cpx #CHARS_PER_LINE
bne .next_char
.print_name_end:
; clear second line
ldy #CHARS_PER_LINE
lda #0
.clear_2nd_line_loop:
sta PPUDATA
dey
bne .clear_2nd_line_loop
jsr set_line_attributes
.end:
pla
tax
pla
tay
pla
rts
set_line_attributes:
; maybe this line already drawned?
lda <TEXT_DRAW_ROW
and #%11111110
cmp <LAST_ATTRIBUTE_ADDRESS
bne .set_attribute_address
rts
.set_attribute_address:
lda #BANK(header_attribute_table) / 2
jsr select_prg_bank
; calculating attributes address
lda <TEXT_DRAW_ROW
cmp #LINES_PER_SCREEN
bcc .first_screen
; second nametable
lda #1
sta TMP ; remember nametable #
lda #$2F
sta PPUADDR
lda <TEXT_DRAW_ROW
sec
sbc #LINES_PER_SCREEN
jmp .nametable_detect_end
; first nametable
.first_screen:
lda #0
sta TMP ; remember nametable #
lda #$23
sta PPUADDR
lda <TEXT_DRAW_ROW
.nametable_detect_end:
; one byte for 4 rows
and #%11111110
asl A
asl A
clc
adc #$C0
sta <LAST_ATTRIBUTE_ADDRESS
sta PPUADDR
; now writing attributes, need to calculate them too
ldx #8
ldy #0
lda <TEXT_DRAW_GAME+1
cmp #HIGH(GAMES_COUNT + 3)
bne .not_footer
lda <TEXT_DRAW_GAME
cmp #LOW(GAMES_COUNT + 3)
beq .footer
jmp .maybe_header_or_game_0
.not_footer:
cmp #0
bne .only_text_attributes
.maybe_header_or_game_0:
lda <TEXT_DRAW_GAME+1
bne .only_text_attributes
lda <TEXT_DRAW_GAME
cmp #0
beq .header_0
cmp #1
beq .header_1
cmp #2
beq .game_0
jmp .only_text_attributes
.header_0
lda TEXT_DRAW_ROW
eor TMP
lsr A
bcc .only_header_attributes
.header_0_loop:
lda header_attribute_table, y
asl A
asl A
asl A
asl A
ora #$0F
sta PPUDATA
iny
dex
bne .header_0_loop
rts
.header_1
lda TEXT_DRAW_ROW
eor TMP
lsr A
bcs .only_header_attributes
.header_1_loop:
lda header_attribute_table, y
lsr A
lsr A
lsr A
lsr A
ora #$F0
sta PPUDATA
iny
dex
bne .header_1_loop
rts
.game_0:
lda TEXT_DRAW_ROW
eor TMP
lsr A
bcc .only_text_attributes
jmp .header_1_loop
.footer:
lda TEXT_DRAW_ROW
eor TMP
lsr A
bcs .only_text_attributes
jmp .header_0_loop
.only_header_attributes:
lda header_attribute_table, y
sta PPUDATA
iny
dex
bne .only_header_attributes
rts
.only_text_attributes:
lda #$FF
.only_text_attributes_loop:
sta PPUDATA
dex
bne .only_text_attributes_loop
rts
move_cursors:
pha
; fine cursor scrolling
lda <SPRITE_1_X_TARGET
cmp SPRITE_1_X
beq .sprite_1x_target_end
bcs .sprite_1x_target_plus
lda SPRITE_1_X
sec
sbc #4
sta SPRITE_1_X
jmp .sprite_1x_target_end
.sprite_1x_target_plus:
lda SPRITE_1_X
clc
adc #4
sta SPRITE_1_X
.sprite_1x_target_end:
lda <SPRITE_Y_TARGET
cmp SPRITE_0_Y
beq .sprite_0y_target_end
bcs .sprite_0y_target_plus
lda SPRITE_0_Y
sec
sbc #4
sta SPRITE_0_Y
.if ENABLE_RIGHT_CURSOR!=0
sta SPRITE_1_Y
.endif
jmp .sprite_0y_target_end
.sprite_0y_target_plus:
lda SPRITE_0_Y
clc
adc #4
sta SPRITE_0_Y
.if ENABLE_RIGHT_CURSOR!=0
sta SPRITE_1_Y
.endif
.sprite_0y_target_end:
pla
rts
; fine scrolling to target line
move_scrolling:
; determining scroll speed
lda <SCROLL_LINES
clc
adc #2
sta <TMP
lda <SCROLL_LINES+1
adc #0
sta <TMP+1
lda <SCROLL_LINES_TARGET
sec
sbc <TMP
lda <SCROLL_LINES_TARGET+1
sbc <TMP+1
bcs .move_scrolling_fast_down
lda <SCROLL_LINES_TARGET
clc
adc #2
sta <TMP
lda <SCROLL_LINES_TARGET+1
adc #0
sta <TMP+1
lda <SCROLL_LINES
sec
sbc <TMP
lda <SCROLL_LINES+1
sbc <TMP+1
bcs .move_scrolling_fast_up
; slow scrolling
jsr .move_scrolling_real
rts
; fast scrolling
.move_scrolling_fast:
jsr .move_scrolling_real
jsr .move_scrolling_real
jsr .move_scrolling_real
jsr .move_scrolling_real
rts
.move_scrolling_fast_up:
jmp scroll_line_up
.move_scrolling_fast_down: