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;
; Written by Groepaz/Hitmen <groepaz@gmx.net>
; Cleanup by Ullrich von Bassewitz <uz@cc65.org>
;
.export ppuinit
.export paletteinit, paldata
.include "nes.inc"
;+---------+----------------------------------------------------------+
;| $2000 | PPU Control Register #1 (W) |
;| | |
;| | D7: Execute NMI on VBlank |
;| | 0 = Disabled |
;| | 1 = Enabled |
;| | D6: PPU Master/Slave Selection --+ |
;| | 0 = Master +-- UNUSED |
;| | 1 = Slave --+ |
;| | D5: Sprite Size |
;| | 0 = 8x8 |
;| | 1 = 8x16 |
;| | D4: Background Pattern Table Address |
;| | 0 = $0000 (VRAM) |
;| | 1 = $1000 (VRAM) |
;| | D3: Sprite Pattern Table Address |
;| | 0 = $0000 (VRAM) |
;| | 1 = $1000 (VRAM) |
;| | D2: PPU Address Increment |
;| | 0 = Increment by 1 |
;| | 1 = Increment by 32 |
;| | D1-D0: Name Table Address |
;| | 00 = $2000 (VRAM) |
;| | 01 = $2400 (VRAM) |
;| | 10 = $2800 (VRAM) |
;| | 11 = $2C00 (VRAM) |
;+---------+----------------------------------------------------------+
;+---------+----------------------------------------------------------+
;| $2001 | PPU Control Register #2 (W) |
;| | |
;| | D7-D5: Full Background Colour (when D0 == 1) |
;| | 000 = None +------------+ |
;| | 001 = Green | NOTE: Do not use more |
;| | 010 = Blue | than one type |
;| | 100 = Red +------------+ |
;| | D7-D5: Colour Intensity (when D0 == 0) |
;| | 000 = None +--+ |
;| | 001 = Intensify green | NOTE: Do not use more |
;| | 010 = Intensify blue | than one type |
;| | 100 = Intensify red +--+ |
;| | D4: Sprite Visibility |
;| | 0 = Sprites not displayed |
;| | 1 = Sprites visible |
;| | D3: Background Visibility |
;| | 0 = Background not displayed |
;| | 1 = Background visible |
;| | D2: Sprite Clipping |
;| | 0 = Sprites invisible in left 8-pixel column |
;| | 1 = No clipping |
;| | D1: Background Clipping |
;| | 0 = BG invisible in left 8-pixel column |
;| | 1 = No clipping |
;| | D0: Display Type |
;| | 0 = Colour display |
;| | 1 = Monochrome display |
;+---------+----------------------------------------------------------+
;-----------------------------------------------------------------------------
.segment "ONCE"
.proc ppuinit
lda #%10101000
sta PPU_CTRL1
lda #%00011110
sta PPU_CTRL2
; Wait for vblank
@wait: lda PPU_STATUS
bpl @wait
; reset scrolling
lda #0
sta PPU_VRAM_ADDR1
sta PPU_VRAM_ADDR1
; Make all sprites invisible
lda #$00
ldy #$f0
sta PPU_SPR_ADDR
ldx #$40
@loop: sty PPU_SPR_IO
sta PPU_SPR_IO
sta PPU_SPR_IO
sty PPU_SPR_IO
dex
bne @loop
rts
.endproc
;-----------------------------------------------------------------------------
.proc paletteinit
; Wait for v-blank
@wait: lda PPU_STATUS
bpl @wait
lda #$3F
sta PPU_VRAM_ADDR2
lda #$00
sta PPU_VRAM_ADDR2
ldx #0
@loop: lda paldata,x
sta PPU_VRAM_IO
inx
cpx #(16*2)
bne @loop
rts
.endproc
;-----------------------------------------------------------------------------
.rodata
paldata:
.repeat 2
.byte $0f ; 0 black
.byte $14 ; 4 violett
.byte $3b ; 3 cyan
.byte $3d ; 1 white
.byte $38 ; 7 yellow
.byte $2d ; b dark grey
.byte $22 ; e light blue
.byte $04 ; 2 red
.byte $18 ; 8 orange
.byte $08 ; 9 brown
.byte $35 ; a light red
.byte $01 ; 6 blue
.byte $10 ; c middle grey
.byte $2b ; d light green
.byte $3d ; f light gray
.byte $1a ; 5 green
.endrepeat
|
