GSCats/graphics.s

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3.7 KiB
ArmAsm
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; colorFill
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; Fills the screen with a color (or two). Pretty fast, but not fastest possible
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; A 4:4:4:4 = Palette entries
; X = Color to fill (doubled)
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;
; Trashes Y
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colorFill:
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FASTGRAPHICS
lda #$9d00-1 ; Point stack to end of VRAM
tcs
ldy #200
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colorFillLoop:
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; 80 PHXs, for 1 line
; We could do the entire screen with PHXs, but this is a
; balance between speed and super-verbose code
.byte $da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da
.byte $da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da
.byte $da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da
.byte $da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da
dey
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bne colorFillLoop
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SLOWGRAPHICS
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rts
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; bottomFill
; Fills the bottom of the screen with a color (or two). Pretty fast, but not fastest possible
; A 4:4:4:4 = Palette entries
; X = Color to fill (doubled)
;
; Trashes Y
bottomFill:
FASTGRAPHICS
lda #$9d00-1 ; Point stack to end of VRAM
tcs
ldy #58
bottomFillLoop:
; 80 PHXs, for 1 line
; We could do the entire screen with PHXs, but this is a
; balance between speed and super-verbose code
.byte $da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da
.byte $da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da
.byte $da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da
.byte $da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da,$da
dey
bne bottomFillLoop
SLOWGRAPHICS
rts
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; initSCBs
; Initialize all scanline control bytes
;
; Trashes A,X
initSCBs:
lda #0
ldx #$0100 ;set all $100 scbs to A
initSCBsLoop:
dex
dex
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sta $e19d00,x
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bne initSCBsLoop
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; setPaletteColor
; Set a single color in a palette
; PARAML0 = 0:Color index
; PARAML1 = 0:R:G:B
; A = Palette index
;
; Trashes X
setPaletteColor:
asl
asl
asl
asl
asl
sta SCRATCHL
lda PARAML0
asl
clc
adc SCRATCHL
tax
lda PARAML1
sta $e19e00,x
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; setPalette
; Set a single color in a palette
; PARAML0 = Pointer to 32 color bytes
; A = Palette index
;
setPalette:
SAVE_XY
asl
asl
asl
asl
asl
tax
ldy #0
setPaletteLoop:
lda (PARAML0),y
sta $e19e00,x
iny
iny
inx
inx
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cpx #32
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bne setPaletteLoop
RESTORE_XY
rts
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; drawNumber
;
; A = Number to render
; X = VRAM position to render at
;
; Trashes PARAML0
;
drawNumber:
sta PARAML0
jsr intToString
lda #intToStringResult
jsr DrawString
rts
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Vertical blank checkers
;
; The Brutal Deluxe version, taken from LemminGS
;
nextVBL:
lda #75
pha
nextVBL0:
lda $e0c02e
and #$7f
cmp 1,s
blt nextVBL0
cmp #100
bge nextVBL0
pla
waitVBL:
lda $e0c018
bpl waitVBL
rts
; The Apple version, taken from GS Tech Note 039
;
syncVBL:
BITS8
syncVBL0:
lda $E0C02F
asl ; VA is now in the Carry flag
lda $E0C02E
rol ; Roll Carry into bit 0
cmp #200 ; A now contains line number
bne syncVBL0
BITS16
rts
; The old style //e version
;
vblSync:
BITS8
waitVBLToFinish:
lda $E0C019
bmi waitVBLToFinish
waitVBLToStart:
lda $E0C019
bpl waitVBLToStart
BITS16
rts
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; caches
shadowRegister:
.byte 0
stackRegister:
.byte 0
stackPtr:
.word 0