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Added .inc directive, and created a NES symbols include file
This commit is contained in:
Safiire
parent
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commit
6d3401b2a5
@ -1,4 +1,4 @@
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# Assembler6502 0.4
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# Assembler6502 0.5
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An NES assembler for the 6502 microprocessor written in Ruby
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@ -61,6 +61,8 @@ An NES assembler for the 6502 microprocessor written in Ruby
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# Some new additions:
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- added .inc directive, to include other .asm files.
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- nes.asm library include file created, naming popular NES addresses
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- C Style in memory structs using .scope and .space directives
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- Explicit usage of zero page instructions with the zp suffix
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- Split the Parser into its own class
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@ -90,8 +92,8 @@ An NES assembler for the 6502 microprocessor written in Ruby
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- Tested a ROM that changes background color
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# Some Todos:
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- Create some documentation.
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- Support binary %10101010 addresses and literals
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- Create a library which names important NES addresses
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- Make macros that can be used interchangably inline or as a subroutine
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- Create a library for common operations, DMA, sound, etc both inline and subroutine options
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- Give this project a better name.
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@ -9,10 +9,17 @@
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; Create an iNES header
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.ines {"prog": 1, "char": 1, "mapper": 0, "mirror": 0}
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;;;;
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; Include all the symbols in the nes scope
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.inc <nes.sym>
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;;;;
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; Open the prog section bank 0
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.segment prog 0
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;;;;
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; Here is a good spot to associate zero page memory addresses
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; to symbols that we can use throughout the program.
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@ -32,6 +39,7 @@
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.space x 1
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.
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;;;;
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; Setup the interrupt vectors
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.org $FFFA
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@ -50,24 +58,24 @@
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; Wait for 2 vblanks
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wait_vb1:
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lda $2002
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lda nes.ppu.status
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bpl wait_vb1
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wait_vb2:
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lda $2002
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lda nes.ppu.status
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bpl wait_vb2
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; Now we want to initialize the hardware to a known state
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lda #$00
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ldx #$00
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clear_segments:
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sta $00, X
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sta $0100, X
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sta $0200, X
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sta $0300, X
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sta $0400, X
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sta $0500, X
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sta $0600, X
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sta $0700, X
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sta $00, x
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sta $0100, x
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sta $0200, x
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sta $0300, x
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sta $0400, x
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sta $0500, x
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sta $0600, x
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sta $0700, x
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inx
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bne clear_segments
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@ -75,10 +83,10 @@
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ldx #$FF
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txs
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; Disable all graphics.
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; Disable all graphics and vblank nmi
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lda #$00
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sta $2000
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sta $2001
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sta nes.ppu.control1
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sta nes.ppu.control2
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jsr init_graphics
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jsr init_input
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@ -95,11 +103,12 @@
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;;;;
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; Set basic PPU registers. Load background from $0000,
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; sprites from $1000, and the name table from $2000.
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; These literals would make more sense in binary.
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.scope init_ppu
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lda #$88
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sta $2000
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sta nes.ppu.control1
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lda #$1E
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sta $2001
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sta nes.ppu.control2
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rts
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.
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@ -123,15 +132,16 @@
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rts
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.
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;;;;
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; Initialize the APU to known values
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.scope init_sound
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lda #$01
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sta $4015
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sta nes.apu.channel_enable
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lda #$00
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sta $4001
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sta nes.apu.square1.reg2
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lda #$40
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sta $4017
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sta nes.controller2 ; Why are we doing this to controller 2? Mistake?
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rts
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.
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@ -149,7 +159,7 @@
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bne sprite_clear1
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; initialize Sprite 0
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lda #$70
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lda #$70 ; Y Coordinate
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sta sprite.y ; Initialize the y value of sprite
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lda #$01
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sta sprite.pattern ; Pattern number 1
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@ -161,22 +171,24 @@
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rts
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.
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;;;;
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; Load palette into $3F00
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.scope load_palette
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lda #$3F
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ldx #$00
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sta $2006
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stx $2006
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sta nes.ppu.address
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stx nes.ppu.address
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loop:
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lda palette, X
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sta $2007
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lda palette, x
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sta nes.ppu.data
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inx
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cpx #$20
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bne loop
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rts
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.
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;;;;
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; Put the ASCII values from bg into the first name table, at $2400
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; The tile values are conveniently mapped to their ASCII values
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@ -184,16 +196,16 @@
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ldy #$00
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ldx #$04
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lda #<bg
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sta $10
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sta $10
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lda #>bg
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sta $11
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lda #$24
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sta $2006
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sta nes.ppu.address
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lda #$00
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sta $2006
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sta nes.ppu.address
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loop:
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lda ($10), Y
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sta $2007
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sta nes.ppu.data
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iny
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bne loop
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inc $11
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@ -205,9 +217,9 @@
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ldy #$00
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ldx #$04
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lda #$00
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.scope ; We can reuse loop, in an anonymous scope, if we want
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.scope
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loop:
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sta $2007
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sta nes.ppu.data
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iny
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bne loop
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dex
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@ -228,38 +240,41 @@
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;;;;
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; Update the sprite, I don't exactly understand this yet.
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; Update the sprite, I don't exactly understand the DMA call yet.
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update_sprite:
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lda #>sprite
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sta $4014 ; Jam page $200-$2FF into SPR-RAM
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sta nes.ppu.sprite_dma ; Jam page $200-$2FF into SPR-RAM, how do we get these numbers?
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lda sprite.x
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beq hit_left
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cmp #$F7
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bne edge_done
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bne edge_done ; Detect hitting either edge
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; Hit right
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ldx #$FF
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stx dx zp
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jsr high_c
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jsr high_c ; And play a high C note if we do
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jmp edge_done
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hit_left:
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ldx #$01
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stx dx zp
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jsr high_c
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hit_left:
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ldx #$01
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stx dx zp
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jsr high_c
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edge_done: ; update X and store it.
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clc
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adc dx zp
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sta sprite.x
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edge_done: ; update X and store it.
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clc
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adc dx zp
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sta sprite.x
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rts
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;;;;
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; Read the first controller, and handle input
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react_to_input:
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lda #$01 ; strobe joypad
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sta $4016
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sta nes.controller1
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lda #$00
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sta $4016
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sta nes.controller1
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lda $4016 ; Is the A button down?
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lda nes.controller1 ; Is the A button down?
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and #$01
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beq not_a
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ldx a_button zp
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@ -270,20 +285,20 @@ react_to_input:
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not_a:
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sta a_button zp ; A has been released, so put that zero into 'a'.
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a_done:
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lda $4016 ; B does nothing
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lda $4016 ; Select does nothing
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lda $4016 ; Start does nothing
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lda $4016 ; Up
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lda nes.controller1 ; B does nothing
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lda nes.controller1 ; Select does nothing
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lda nes.controller1 ; Start does nothing
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lda nes.controller1 ; Up
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and #$01
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beq not_up
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ldx sprite.y ; Load Y value
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ldx sprite.y ; Load Y value
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cpx #$07
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beq not_up ; No going past the top of the screen
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beq not_up ; No going past the top of the screen
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dex
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stx sprite.y
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not_up:
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lda $4016 ; Down
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lda nes.controller1 ; Down
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and #$01
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beq not_dn
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ldx sprite.y
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@ -292,59 +307,68 @@ react_to_input:
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inx
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stx sprite.y
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not_dn:
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rts ; Ignore left and right, we don't use 'em
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rts ; Ignore left and right
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;;;;
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; XORing with $ff toggles between 0x1 and 0xfe (-1)
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reverse_dx:
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lda #$FF
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eor dx zp ; dx Toggles between 0x1 and 0xfe (-1)
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eor dx zp
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clc
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adc #$01 ; add dx, and store to variable
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adc #$01 ; Add dx, and store to variable
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sta dx zp
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jsr low_c
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jsr low_c ; Play the reverse low C note
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rts
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scroll_screen:
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ldx #$00 ; Reset VRAM
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stx $2006
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stx $2006
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ldx scroll zp ; scroll ; Do we need to scroll at all?
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;;;;
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; Scroll the screen if we have to
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scroll_screen:
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ldx #$00 ; Reset VRAM Address to $0000
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stx nes.ppu.address
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stx nes.ppu.address
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ldx scroll zp ; Do we need to scroll at all?
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beq no_scroll
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dex
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stx scroll zp ; scroll
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stx scroll zp
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lda #$00
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sta $2005 ; Write 0 for Horiz. Scroll value
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stx $2005 ; Write the value of 'scroll' for Vert. Scroll value
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sta nes.ppu.scroll ; Write 0 for Horiz. Scroll value
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stx nes.ppu.scroll ; Write the value of 'scroll' for Vert. Scroll value
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no_scroll:
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rts
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;;;;
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; I am pretty sure this plays a low C note on the Square wave
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; Play a low C note on square 1
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low_c:
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pha
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lda #$84
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sta $4000
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sta nes.apu.square1.reg1
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lda #$AA
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sta $4002
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sta nes.apu.square1.reg3
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lda #$09
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sta $4003
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sta nes.apu.square1.reg4
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pla
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rts
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;;;;
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; I am pretty sure this plays a high C note on the Square wave
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; Play a high C note on square 1
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high_c:
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pha
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lda #$86
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sta $4000
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sta nes.apu.square1.reg1
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lda #$69
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sta $4002
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sta nes.apu.square1.reg3
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lda #$08
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sta $4003
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sta nes.apu.square1.reg4
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pla
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rts
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;;;;
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; Update everything on every vblank
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vblank:
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67
lib/directives/inc.rb
Normal file
67
lib/directives/inc.rb
Normal file
@ -0,0 +1,67 @@
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require_relative '../instruction_base'
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module Assembler6502
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####
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## This directive instruction can include another asm file
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class Inc < InstructionBase
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#### System include directory
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SystemInclude = File.dirname(__FILE__) + "/../../nes_lib"
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#### Custom Exceptions
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class FileNotFound < StandardError; end
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####
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## Try to parse an incbin directive
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def self.parse(line)
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## Do We have a system directory include?
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match_data = line.match(/^\.inc <([^>]+)>$/)
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unless match_data.nil?
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filename = File.join(SystemInclude, match_data[1])
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return Inc.new(filename)
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end
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## Do We have a project relative directory include?
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match_data = line.match(/^\.inc "([^"]+)"$/)
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unless match_data.nil?
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filename = File.join(Dir.pwd, match_data[1])
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return Inc.new(filename)
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end
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## Nope, not an inc directive
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nil
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end
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####
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## Initialize with filename
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def initialize(filename)
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@filename = filename
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end
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####
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## Execute on the assembler
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def exec(assembler)
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unless File.exists?(@filename)
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fail(FileNotFound, ".inc can't find #{@filename}")
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end
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File.read(@filename).split(/\n/).each do |line|
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assembler.assemble_one_line(line)
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end
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end
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####
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## Display
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def to_s
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".inc \"#{@filename}\""
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end
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end
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end
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@ -6,6 +6,7 @@ module Assembler6502
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require_relative 'directives/org'
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require_relative 'directives/segment'
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require_relative 'directives/incbin'
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require_relative 'directives/inc'
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require_relative 'directives/dw'
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require_relative 'directives/bytes'
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require_relative 'directives/ascii'
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@ -25,7 +26,7 @@ module Assembler6502
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class CannotParse < StandardError; end
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Directives = [INESHeader, Org, Segment, IncBin, DW, Bytes, ASCII, EnterScope, ExitScope, Space]
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Directives = [INESHeader, Org, Segment, IncBin, Inc, DW, Bytes, ASCII, EnterScope, ExitScope, Space]
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####
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## Parses a line of program source into an object
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65
nes_lib/nes.sym
Normal file
65
nes_lib/nes.sym
Normal file
@ -0,0 +1,65 @@
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; Let's start a little library for naming parts of memory in the NES
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; We can move this to a separate library file later.
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;
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; Including this file will not emit any instructions or data into your binary
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; It only defines symbols in the symbol table to name memory addresses
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;
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; Author: Saf Allen 2015
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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.org $0000
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.scope nes
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.scope ppu
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.org $2000
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.space control1 1 ; Control registers 1 and 2
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.space control2 1
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.space status 1 ; PPU status
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.space sprite_address 1 ; Sprite memory address
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.space sprite_data 1 ; Sprite memory data
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.space scroll 1 ; Background scroll
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.space address 1 ; Indexing into PPU memory address
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.space data 1 ; Read or write to PPU memory location through this register
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.org $4014
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.space sprite_dma 1 ; DMA access to sprite memory
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.
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.org $4000
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.scope apu
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.scope square1 ; Control of Square 1
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.space reg1 1
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.space reg2 1
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.space reg3 1
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.space reg4 1
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.
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.scope square2 ; Control of Square 2
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.space reg1 1
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.space reg2 1
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.space reg3 1
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.space reg4 1
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.
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.scope triangle ; Control of Triangle
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.space reg1 1
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.space reg2 1
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.space reg3 1
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.space reg4 1
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.
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.scope noise ; Control of Noise
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.space reg1 1
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.space reg2 1
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.space reg3 1
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.space reg4 1
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.
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.scope dmc ; Control of DMC
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.space reg1 1
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.space reg2 1
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.space reg3 1
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.space reg4 1
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.
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.org $4015
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.space channel_enable 1 ; Enable or disble channels
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.
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.org $4016
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.space controller1 1 ; Player 1 joystick
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.space controller2 1 ; Player 2 joystick
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.
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