background colors
This commit is contained in:
Tyrel Souza
parent
e58a6330d9
commit
db9827a299
11
helloppu/consts.inc
Executable file
11
helloppu/consts.inc
Executable file
@ -0,0 +1,11 @@
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Constants for PPU registers mapped from addresses $2000 to $2007
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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PPU_CTRL = $2000
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PPU_MASK = $2001
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PPU_STATUS = $2002
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OAM_ADDR = $2003
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OAM_DATA = $2004
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PPU_SCROLL = $2005
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PPU_ADDR = $2006
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PPU_DATA = $2007
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13
helloppu/header.inc
Normal file
13
helloppu/header.inc
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; The iNES header (contains a total of 16 bytes with the header flags)
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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.segment "HEADER"
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.byte $4E,$45,$53,$1A ; 4 bytes with the characters 'N','E','S','\n'
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.byte $02 ; How many 16KB of PRG-ROM we'll use (=32KB)
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.byte $01 ; How many 8KB of CHR-ROM we'll use (=8KB)
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.byte %00000000 ; Horz mirroring, no battery, mapper 0
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.byte %00000000 ; mapper 0, playchoice, NES 2.0
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.byte $00 ; No PRG-RAM
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.byte $00 ; NTSC TV format
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.byte $00 ; Extra flags for TV format and PRG-RAM
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.byte $00,$00,$00,$00,$00 ; Unused padding to complete 16 bytes of header
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@ -1,83 +1,42 @@
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Constants for PPU registers mapped from addresses $2000 to $2007
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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PPU_CTRL = $2000
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PPU_MASK = $2001
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PPU_STATUS = $2002
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OAM_ADDR = $2003
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OAM_DATA = $2004
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PPU_SCROLL = $2005
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PPU_ADDR = $2006
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PPU_DATA = $2007
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; The iNES header (contains a total of 16 bytes with the flags at $7F00)
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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.segment "HEADER"
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.byte $4E,$45,$53,$1A ; 4 bytes with the characters 'N','E','S','\n'
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.byte $02 ; How many 16KB of PRG-ROM we'll use (=32KB)
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.byte $01 ; How many 8KB of CHR-ROM we'll use (=8KB)
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.byte %00000000 ; Horz mirroring, no battery, mapper 0
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.byte %00000000 ; mapper 0, playchoice, NES 2.0
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.byte $00 ; No PRG-RAM
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.byte $00 ; NTSC TV format
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.byte $00 ; Extra flags for TV format and PRG-RAM
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.byte $00,$00,$00,$00,$00 ; Unused padding to complete 16 bytes of header
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.include "consts.inc"
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.include "header.inc"
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.include "reset.inc"
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; PRG-ROM code located at $8000
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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.segment "CODE"
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.proc LoadPalette
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ldy #0
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LoopPalette: ;unnamed label
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lda PaletteData,y ; lookup byte in ROM
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sta PPU_DATA ; set the value to send to PPU_DATA,
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; will auto increment PPU_ADDR
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iny
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cpy #32
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bne LoopPalette ; loop to previous label
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rts ;return from subroutine
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.endproc
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Reset handler (called when the NES resets or powers on)
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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Reset:
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sei ; Disable all IRQ interrupts
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cld ; Clear decimal mode (not supported by the NES)
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ldx #$FF
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txs ; Initialize the stack pointer at address $FF
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inx ; Increment X, causing a rolloff from $FF to $00
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stx PPU_CTRL ; disable NMI
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stx PPU_MASK ; disable rendering
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stx $4010 ; disable DMC IRQs
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lda #$40
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sta $4017 ; disable APU frame IRQ
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Wait1stVBlank:
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bit PPU_STATUS
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bpl Wait1stVBlank
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txa ; A = 0
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ClearRAM:
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sta $0000,x ; Zero RAM addresses from $0000 to $00FF
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sta $0100,x ; Zero RAM addresses from $0100 to $01FF
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sta $0200,x ; Zero RAM addresses from $0200 to $02FF
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sta $0300,x ; Zero RAM addresses from $0300 to $03FF
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sta $0400,x ; Zero RAM addresses from $0400 to $04FF
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sta $0500,x ; Zero RAM addresses from $0500 to $05FF
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sta $0600,x ; Zero RAM addresses from $0600 to $06FF
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sta $0700,x ; Zero RAM addresses from $0700 to $07FF
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inx
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bne ClearRAM
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Wait2ndVBlank:
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bit PPU_STATUS
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bpl Wait2ndVBlank ; bit-7 is 1
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INIT_NES
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Main:
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bit PPU_STATUS ; reset the latch
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ldx #$3F
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stx PPU_ADDR
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ldx #$00
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stx PPU_ADDR
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lda #$25
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sta PPU_DATA
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jsr LoadPalette ;jump to subroutine
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lda %00011110
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lda #%00011110
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sta PPU_MASK
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LoopForever:
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@ -95,6 +54,10 @@ NMI:
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IRQ:
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rti ; Return from interrupt
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PaletteData:
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.byte $0F,$2A,$0C,$3A, $0F,$2A,$0C,$3A, $0F,$2A,$0C,$3A, $0F,$2A,$0C,$3A ; background
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.byte $0F,$10,$00,$26, $0F,$10,$00,$26, $0F,$10,$00,$26, $0F,$10,$00,$26 ; sprite
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Vectors with the addresses of the handlers that we always add at $FFFA
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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38
helloppu/reset.inc
Normal file
38
helloppu/reset.inc
Normal file
@ -0,0 +1,38 @@
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.macro INIT_NES
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sei ; Disable all IRQ interrupts
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cld ; Clear decimal mode (not supported by the NES)
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ldx #$FF
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txs ; Initialize the stack pointer at address $FF
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inx ; Increment X, causing a rolloff from $FF to $00
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stx PPU_CTRL ; disable NMI
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stx PPU_MASK ; disable rendering
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stx $4010 ; disable DMC IRQs
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lda #$40
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sta $4017 ; disable APU frame IRQ
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Wait1stVBlank:
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bit PPU_STATUS
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bpl Wait1stVBlank
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txa ; A = 0
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ClearRAM:
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sta $0000,x ; Zero RAM addresses from $0000 to $00FF
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sta $0100,x ; Zero RAM addresses from $0100 to $01FF
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sta $0200,x ; Zero RAM addresses from $0200 to $02FF
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sta $0300,x ; Zero RAM addresses from $0300 to $03FF
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sta $0400,x ; Zero RAM addresses from $0400 to $04FF
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sta $0500,x ; Zero RAM addresses from $0500 to $05FF
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sta $0600,x ; Zero RAM addresses from $0600 to $06FF
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sta $0700,x ; Zero RAM addresses from $0700 to $07FF
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inx
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bne ClearRAM
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Wait2ndVBlank:
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bit PPU_STATUS
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bpl Wait2ndVBlank ; bit-7 is 1
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.endmacro
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