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GSCats/graphics.s
blondie7575 06527a3f61 Added help screen
2023-08-06 15:55:42 -07:00

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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; colorFill
; Fills the screen with a color (or two). Pretty fast, but not fastest possible
; X = 4:4:4:4 = Palette entries to fill
; Y = Scanline count (fills backwards to 0)
;
; Trashes A,Y,PARAML0,PARAML1
colorFill:
; Calculate end of VRAM we're going to touch
sty PARAML0
lda #160 ; Bytes per row in VRAM
sta PARAML1
phx
jsr mult16
clc
adc #$2000
dec ; A now holds address of highest byte we'll touch (e.g. $9d00-1 for full screen fill)
sta PARAML0 ; Cache values for highspeed zone
sty PARAML1
plx
FASTGRAPHICS
lda PARAML0
tcs
ldy PARAML1
colorFillLoop:
; 80 PHXs, for 1 line
; We could do the entire screen with PHXs, but this is a
; balance between speed and code size
.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 colorFillLoop
SLOWGRAPHICS
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; 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
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; initSCBs
; Initialize all scanline control bytes
;
; Trashes A,X
initSCBs:
lda #0
ldx #200 ;set all 200 scbs to A
initSCBsLoop:
dex
dex
sta $e19d00,x
bne initSCBsLoop
jsr setScanLineInterruptVector
jsr setVBLInterruptVector
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; setScanLineInterruptVector
;
; Install scanline interrupt handler
;
setScanLineInterruptVector:
; Save current handler
lda $e10029
sta scanlineHandlerCache
BITS8A
lda $e1002b
sta scanlineHandlerCache+2
BITS16
; Set our handler
lda #scanLineInterruptHandler
sta $e10029
BITS8A
lda #2 ; This code bank
sta $e1002b
BITS16
rts
scanlineHandlerCache:
.byte 0,0,0
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; unsetScanLineInterruptVector
;
; Remove scanline interrupt handler
;
unsetScanLineInterruptVector:
; Turn off scanline interrupts
BITS8A
lda $e0c023 ; Disable scaline interrupts
and #%11111101
sta $e0c023
BITS16
; Restore saved handler
lda scanlineHandlerCache
sta $e10029
BITS8A
lda scanlineHandlerCache+2
sta $e1002b
BITS16
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; setVBLInterruptVector
;
; Install VBL interrupt handler
;
setVBLInterruptVector:
; Save current handler
lda $e10031
sta vblHandlerCache
BITS8A
lda $e10033
sta vblHandlerCache+2
BITS16
; Set our handler
lda #vblInterruptHandler
sta $e10031
BITS8A
lda #2 ; This code bank
sta $e10033
BITS16
; Enable VBL interrupts
lda $e0c041
ora #%00001000
sta $e0c041
rts
vblHandlerCache:
.byte 0,0,0
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; unsetVBLInterruptVector
;
; Remove VBL handler
;
unsetVBLInterruptVector:
; Turn off VBL interrupts
BITS8A
lda $e0c041 ; Disable VBL interrupts
and #%11110111
sta $e0c041
BITS16
; Restore saved handler
lda vblHandlerCache
sta $e10031
BITS8A
lda vblHandlerCache+2
sta $e10033
BITS16
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; vblInterruptHandler
;
; Handler for IRQ.VBL (vector E1/0030-0033)
;
vblInterruptHandler:
OP8
lda #0 ; Clear scanline interrupt source
sta $e0c047
; lda BORDERCOLOR
; and #$f0
; ora #$7 ; Set to sky at bottom of screen
; sta BORDERCOLOR
clc
rtl
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; setBorderAtScanLine
;
; Trashes A
;
setBorderAtScanLine:
BITS8A
lda $e19d92 ; Enable interrupt on scanline 146
ora #%01000000
sta $e19d92
lda $e19dc7 ; Enable interrupt on scanline 199
ora #%01000000
sta $e19dc7
lda $e0c023 ; Enable scaline interrupts, if needed
ora #%00000010
sta $e0c023
BITS16
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; scanLineInterruptHandler
;
; Handler for IRQ.SCAN (vector E1/0028-002B)
;
scanLineInterruptHandler:
OP8
lda $e0c032 ; Clear scanline interrupt source
and #%11011111
sta $e0c032
lda $e0C02f
asl ; VA is now in the Carry flag
lda $e0C02e
rol ; Roll Carry into bit 0. A now contains line number
cmp #155
bcc scanLineInterruptHandler0
lda BORDERCOLOR ; Set border color
and #$f0
ora #$7 ; Set to sky at bottom of screen
sta BORDERCOLOR
bra scanLineInterruptHandlerDone
scanLineInterruptHandler0:
lda BORDERCOLOR ; Set border color to grass at given scanline
and #$f0
ora #$4
sta BORDERCOLOR
scanLineInterruptHandlerDone:
clc
rtl
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; setScanlinePalette
; Set the palette for a given scan line
;
; PARAML0 = Palette index
; X = Start scan line
; Y = Count
setScanlinePalette:
pha
setScanlinePaletteLoop:
lda $e19d00,x
ora PARAML0
sta $e19d00,x
inx
dey
bne setScanlinePaletteLoop
pla
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; enableFillMode
; Enables fill mode for a given scanline
;
; X = Scan line
;
enableFillMode:
SAVE_AXY
BITS8
lda $e19d00,x
ora #%00100000
sta $e19d00,x
BITS16
RESTORE_AXY
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; disableFillMode
; Disables fill mode for a given scanline
;
; X = Scan line
;
; Trashes A
disableFillMode:
SAVE_AXY
BITS8
lda $e19d00,x
and #%11011111
sta $e19d00,x
BITS16
RESTORE_AXY
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; drawNumber
;
; A = Number to render
; X = VRAM position to render at
;
; Trashes PARAML0
;
drawNumber:
SAVE_AXY
sta PARAML0
jsr intToString
lda #intToStringResult
sta PARAML0
txy
lda #1
jsl renderStringFar
RESTORE_AXY
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; drawSpriteBankSafe
;
; A slightly slower version of Mr Sprite's DrawSpriteBank that
; preserves all registers and requires no secret flag clearing
;
; Y = VRAM position at which to draw
; A = Sprite Index
;
drawSpriteBankSafe:
SAVE_AXY
clc
jsr DrawSpriteBank
RESTORE_AXY
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; syncOverscanBottom
;
; Waits for the bottom edge of the overscan region (give or take)
syncOverscanBottom:
BITS8
syncOverscanBottom0:
ldaA $C02f
asl ; VA is now in the Carry flag
ldaA $C02e
rol ; Roll Carry into bit 0
cmp #215 ; A now contains line number
blt syncOverscanBottom0
BITS16
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Alternate vertical blank checkers
;
; The Apple version, taken from GS Tech Note 039
;
syncVBL:
;sei
BITS8
syncVBL0:
ldaA $C02f
asl ; VA is now in the Carry flag
ldaA $C02e
rol ; Roll Carry into bit 0
cmp #200 ; A now contains line number
blt syncVBL0
BITS16
;cli
rts
; The old style //e version
;
vblSync:
BITS8
waitVBLToFinish:
lda $E0C019
bmi waitVBLToFinish
waitVBLToStart:
lda $E0C019
bpl waitVBLToStart
BITS16
rts
.include "spritebank.s"
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