;

; Chart EFF

;

__CHARTSIMPORT = 1

.include "build/tetris.inc"

.include "ips.inc"

.include "tetris-tbl.inc"

.include "chart.inc"

.export levelEffs

.export drawChartBackground

.export drawChartSprites

.export chartEffConvert

; The chart consists of 20 bars within the playfield. The bottom of each bar is

; drawn using the nametable. The nametable tiles are coarse, so are only used

; for each full 8 pixels of bar height. This uses 4 tiles (although we could

; reuse 2 tiles). The topmost pixel of the bar is purposefully excluded since

; it is a different color. The top of the bar (1-8 pixels) is drawn using a

; sprite, which can be placed precisely in the proper position. We make sure

; to always have 8 pixels-worth of sprite height, since that is the maximum that

; can be missed from the nametable. The nametable handles gridlines, so the

; sprite is placed behind the nametable to let the gridline show on top of the

; bars. The gridlines require a duplicate of each nametable tile, which uses 4

; more tiles.

;

; We go well out of our way to reduce the number of sprites per scanline. For

; every two bars (8 pixels of width) we "reserve" 1 sprite per scanline. Since

; there is a maximum of 20 bars to display, this can reach the 8

; sprite-per-scanline limit after 16 bars. But that's only in the worst-case.

; Generally we can hope to "luck out" since games of 200 lines are uncommon

; and are unlikely to have consistent enough EFF to cause 9+ sprites to share a

; scanline.

;

; If we weren't concerned with the 8 sprite limit, we would only need one tile

; for the sprite. However, we choose to use 9 more tiles to reduce the sprite

; load per scanline. Eight of the tiles are for a relative difference between

; the two bars, but they may only provide 1 pixel of bar height. So we have

; another tile that provides 7 more pixels of height to both bars. Note that it

; is important to only add 7 pixels, because any more would increase the

; smallest bar size we could display.

.segment "GAMEBSS"

levelEffs:

.res chartBarCount

.segment "CODE"

; Playfield is unused once curtain starts falling

barScratch := playfield

barOffset = 0

barLength = $06 ; 300/chartValuePerPixel/8, rounded up

drawChartBackground:

; We can't draw anything less than 8 pixels high

ldx #$00

@checkRange:

lda levelEffs,x

beq @rangeOkay

cmp #$08

bpl @rangeOkay

lda #$08

sta levelEffs,x

@rangeOkay:

inx

cpx #chartBarCount

bne @checkRange

ldx #playfieldLiteralSize

@copyLiteral:

lda playfieldLiteral-1,x

sta playfieldLiteralDest-1,x

dex

bne @copyLiteral

ldx #chartBarCount/2

stx tmp1

@drawBar:

dec tmp1

ldx #barLength

lda #full_bar_none

@clearCell:

dex

sta barScratch,x

bne @clearCell

lda tmp1

asl

tax

ldy levelEffs,x

beq @skipFirst

dey

tya

lsr

lsr

lsr

tax

beq @skipFirst

lda #full_bar_left

@setFirst:

dex

sta barScratch,x

bne @setFirst

@skipFirst:

lda tmp1

asl

tax

ldy levelEffs+1,x

beq @skipSecond

dey

tya

lsr

lsr

lsr

tax

beq @skipSecond

@setSecond:

inc barScratch-1,x

dex

bne @setSecond

@skipSecond:

lda barScratch+1

clc

adc #full_bar_none_gridline-full_bar_none

sta barScratch+1

lda barScratch+3

adc #full_bar_none_gridline-full_bar_none

sta barScratch+3

lda barScratch+5

adc #full_bar_none_gridline-full_bar_none

sta barScratch+5

lda #(20-barLength)*10+barOffset

clc

adc tmp1

ldx #barLength

tay

@cellToPpu:

lda barScratch-1,x

sta playfield,y

tya

adc #10

tay

dex

bne @cellToPpu

lda tmp1

bne @drawBar

rts

; We always use two sprites per pair of columns. If the columns are close in

; size, then we use an offset double endcap plus a sprite of 7 pixels of bar.

; If the columns have over a 7 pixel difference, then we use one lone endcap

; per bar.

drawChartSprites:

ldx #$00

@barEndcap:

lda levelEffs,x

beq @skip

lda #$22 ; behind background; sprite palette 2

sta tmp2

txa

asl a

asl a

sta spriteXOffset

lda levelEffs+1,x

beq @diffTooLarge

sec

sbc levelEffs,x

bmi @negative

cmp #$08

bmi @positive

@diffTooLarge:

; Draw the two bars separately

lda #endcap

sta tmp1

lda levelEffs,x

sta spriteYOffset

jsr stageChartSprite

lda levelEffs+1,x

beq @skip

sta spriteYOffset

lda #$62 ; behind background; sprite palette 2; flip horiz

sta tmp2

jsr stageChartSprite

jmp @skip

@positive:

sta tmp1

lda levelEffs,x

sta spriteYOffset

bne @computedDiff ; unconditional

@negative:

cmp #<(-$07)

bmi @diffTooLarge

eor #$FF

clc

adc #$01

sta tmp1

lda levelEffs+1,x

sta spriteYOffset

lda #$62 ; behind background; sprite palette 2; flip horiz

sta tmp2

@computedDiff:

lda #$07

clc

adc spriteYOffset

sta spriteYOffset

lda #endcap_diff_0

clc

adc tmp1

sta tmp1

jsr stageChartSprite

lda #sevenpx_bar_both

sta tmp1

lda spriteYOffset

sec

sbc #$08

sta spriteYOffset

jsr stageChartSprite

@skip:

inx

inx

cpx #chartBarCount

bne @barEndcap

rts

; Stage sprite for chart. Does not use reg x.

; spriteYOffset: (input) relative to playfield; positive is up

; spriteXOffset: (input) relative to playfield

; tmp1: (input) tile index

; tmp2: (input) attributes

stageChartSprite:

lda #$2F+20*8

sec

sbc spriteYOffset

ldy oamStagingLength

sta oamStaging,y

inc oamStagingLength

iny

lda tmp1

sta oamStaging,y

inc oamStagingLength

iny

lda tmp2

sta oamStaging,y

inc oamStagingLength

iny

lda spriteXOffset

clc

adc #$60+barOffset*8

sta oamStaging,y

inc oamStagingLength

iny

rts

PRECISION = 1

; Divide 8 bit number by 3. Implemented via multiplying by a fixed-point 1/3.

; 1/3 is encoded as $55 in a binary byte, but since it is truncated the product

; may be too small. This produces results like 3/3 = 0 and 6/3 = 1. So instead,

; we use $56, which fixes the issue with numbers smaller than 128. To fix

; numbers up to 255, we compute two more bits of precision using $156.

;

; req a: (input) dividend

; (output) quotient

.if 0

div3:

sta tmp1

lsr

.ifdef PRECISION

clc

adc tmp1

ror

lsr

.endif

clc

adc tmp1

ror

lsr

clc

adc tmp1

ror

lsr

clc

adc tmp1

ror

lsr

rts

chartEffConvert := div3

.else

; Divide by 3.125. Implemented by multiplying by fixed-point 1/3.125=0.32.

; Encoded as binary it is $52. That produces quite acceptable results but

; for 6 numbers it rounds up, like with 128 (the smallest failure) it produces

; 41 when the precise answer is 40.96 (all the wrong answers are off by .04).

; To fix those cases requires adding 4 more bits to have $51F.

;

; req a: (input) dividend

; (output) quotient

div3125:

.ifndef PRECISION

sta tmp1

lsr

lsr

lsr

clc

adc tmp1

ror

lsr

clc

adc tmp1

ror

lsr

rts

.else

sta tmp1

lsr

clc

adc tmp1

ror

clc

adc tmp1

ror

clc

adc tmp1

ror

clc

adc tmp1

ror

lsr

lsr

lsr

clc

adc tmp1

ror

lsr

clc

adc tmp1

ror

lsr

rts

.endif

chartEffConvert := div3125

.endif

playfieldLiteralDest := playfield+(20-6-3)*10

playfieldLiteralSize = 30

playfieldLiteral:

set_tbl CHR01+CHR_RIGHT

.byte " "

.byte " EFF LOG "

.byte " "

.export chart_attributetable_patch

chart_attributetable_patch:

.byte $23,$E3,$03,$FA,$FA,$FE

.byte $FF

.segment "IPSCHR_40"

endcap_diff_0 = $40

ips_tile_segment "IPSCHR_40",CHR01+CHR_RIGHT,endcap_diff_0

; endcap difference = 0

.incbin "build/taus.chrs/10"

; endcap difference = 1

.incbin "build/taus.chrs/11"

; endcap difference = 2

.incbin "build/taus.chrs/12"

; endcap difference = 3

.incbin "build/taus.chrs/13"

; endcap difference = 4

.incbin "build/taus.chrs/14"

; endcap difference = 5

.incbin "build/taus.chrs/15"

; endcap difference = 6

.incbin "build/taus.chrs/16"

; endcap difference = 7

.incbin "build/taus.chrs/17"

full_bar_none = $48

; blank

.incbin "build/taus.chrs/20"

; |

.incbin "build/taus.chrs/21"

full_bar_left = $4A

; |

.incbin "build/taus.chrs/22"

; ||

.incbin "build/taus.chrs/23"

sevenpx_bar_both = $4C

; || 7 pixel high

.incbin "build/taus.chrs/19"

endcap = $4D

; endcap

.incbin "build/taus.chrs/18"

.segment "IPSCHR_50"

full_bar_none_gridline = $50

ips_tile_segment "IPSCHR_50",CHR01+CHR_RIGHT,full_bar_none_gridline

; blank, with gridline

.incbin "build/taus.chrs/24"

; |, with gridline

.incbin "build/taus.chrs/25"

; |, with gridline

.incbin "build/taus.chrs/26"

; ||, with gridline

.incbin "build/taus.chrs/27"