User:Banshaku/CA65 Constants

; NES registers: PPU releated
;--------------------------------------------------------
; PPU Controler (write)
; Various flags controlling PPU operation
;
;Input:
;========
;76543210
;||||||||
;||||||++- Base nametable address
;||||||    (0 = $2000; 1 = $2400; 2 = $2800; 3 = $2C00)
;|||||+--- VRAM address increment per CPU read/write of PPUDATA
;|||||     (0: increment by 1, going across; 1: increment by 32, going down)
;||||+---- Sprite pattern table address for 8x8 sprites (0: $0000; 1: $1000)
;|||+----- Background pattern table address (0: $0000; 1: $1000)
;||+------ Sprite size (0: 8x8; 1: 8x16)
;|+------- PPU master/slave select (has no effect on the NES)
;+-------- Generate an NMI at the start of the vertical blanking interval (0: off; 1: on)
;--------------------------------------------------------
PPU_CTRL   = $2000

; Flags for PPU
PPU_CTRL_ADR_NT0    = %00000000 ; Select name table 0
PPU_CTRL_ADR_NT1    = %00000001 ; Select name table 1
PPU_CTRL_ADR_NT2    = %00000010 ; Select name table 2
PPU_CTRL_ADR_NT3    = %00000011 ; Select name table 3
PPU_CTRL_INC32      = %00000100 ; Increment PPU address by 32 bytes, going down
PPU_CTRL_SPR_PT1    = %00001000 ; Sprite pattern table 1
PPU_CTRL_BG_PT1     = %00010000 ; Background pattern table 1
PPU_CTRL_SPR_8x16   = %00100000 ; Sprites are 8x16
PPU_CTRL_NMI        = %10000000 ; write this value to PPUCTRL to enable NMI

;--------------------------------------------------------
; PPU Mask (write)
; Screen enable, masking, and intensity 
;
;Input:
;========
;76543210
;||||||||
;|||||||+- Grayscale (0: normal color; 1: AND all palette entries
;|||||||   with 0x30, effectively producing a monochrome display;
;|||||||   note that colour emphasis STILL works when this is on!)
;||||||+-- Enable background in leftmost 8 pixels of screen (0: clip; 1: display)
;|||||+--- Enable sprite in leftmost 8 pixels of screen (0: clip; 1: display)
;||||+---- Enable background rendering
;|||+----- Enable sprite rendering
;||+------ Intensify reds (and darken other colors)
;|+------- Intensify greens (and darken other colors)
;+-------- Intensify blues (and darken other colors)
;--------------------------------------------------------
PPU_MASK    = $2001

PPU_MASK_GREYSCALE  = %00000001 ; All colors becomes grey scales
PPU_MASK_BG_NOCLIP  = %00000010 ; enables background no clip
PPU_MASK_SPR_NOCLIP = %00000100 ; enables sprite no clip
PPU_MASK_BG_ON      = %00001000 ; enables background rendering
PPU_MASK_SPR_ON     = %00010000 ; enables sprite rendering
PPU_MASK_INT_RED    = %00100000 ; Intensify red
PPU_MASK_INT_GREEN  = %01000000 ; Intensify green
PPU_MASK_INT_BLUE   = %10000000 ; Intensify blue


;--------------------------------------------------------
; PPU status (read)
; 
;
; Caution: Reading PPUSTATUS at the exact start of vertical blank will return a 0 
;          in D7 but clear the latch anyway, causing the program to miss frames. See 
;          NMI for details.
;
;output:
;========
;76543210
;||||||||
;|||+++++- Unimplemented
;||+------ Sprite overflow. The PPU can handle only eight sprites on one
;||        scanline and sets this bit if it starts dropping sprites.
;||        Normally, this triggers when there are 9 sprites on a scanline,
;||        but the actual behavior is significantly more complicated.
;|+------- Sprite 0 Hit.  Set when a nonzero pixel of sprite 0 'hits'
;|         a nonzero background pixel.  Used for raster timing.
;+-------- Vertical blank has started (0: not in VBLANK; 1: in VBLANK)
;--------------------------------------------------------
PPU_STATUS = $2002 ; Can be read to get current PPU status

PPU_STATUS_SPR_OVERFLOW = %00100000 ; More than 8 sprites per scanline
PPU_STATUS_SPRITE0      = %01000000 ; Sprite 0 was hit
PPU_STATUS_IN_VBLANK    = %10000000 ; The vlbank as started

;--------------------------------------------------------
; OAM address (write)
;
; Write the address of OAM you want to access here. Most games just 
; write $00 here and then use OAM_DMA ($4014).
;
; This register also seems to affect Sprite 0 Hit, though it is not
; yet understood exactly how it does. The upper 5 bits of this register 
; seem to select which SPR-RAM data is used for sprites 0 and 1 (instead 
; of the first 8 bytes of SPR-RAM), though actual behavior varies between resets. 
;--------------------------------------------------------
PPU_OAM_ADDR  = $2003 ; OAM address. Rarerly used (why?)


;--------------------------------------------------------
; OAM data port (r/w)
;
; Write OAM data here. Writes will increment OAMADDR; reads won't.
;
; Most games access this register through $4014 instead. Reading 
; OAMDATA while the PPU is rendering will expose internal OAM accesses 
; during sprite evaluation and loading; Micro Machines does this. 
;--------------------------------------------------------
PPU_OAM_DATA = $2004 ; OAM data port


;--------------------------------------------------------
; Scroll register (2x write)
;
; After reading PPUSTATUS to reset the address latch, write the horizontal
; and vertical scroll offsets here just before turning on the screen:
;
; Example:
; 	bit PPUSTATUS
; 	; possibly other code goes here
; 	lda cam_position_x
; 	sta PPUSCROLL
; 	lda cam_position_y
; 	sta PPUSCROLL
;
; Horizontal offsets range from 0 to 255. "Normal" vertical offsets range from
; 0 to 239. (Values of 240 to 255 are treated as -16 through -1 in a way, pulling 
; tile data from the attribute table.)
;--------------------------------------------------------
PPU_SCROLL = $2005 ; Sets X/Y scrolling of background


;--------------------------------------------------------
; VRAM address register (2x write)
;
; After reading PPUSTATUS to reset the address latch, write the 
; 16-bit address of VRAM you want to access here, upper byte first. 
; Valid addresses are $0000-$3FFF.
;
; Access to PPUSCROLL and PPUADDR during screen refresh produces 
; interesting raster effects; the starting position of each scanline 
; can be set to any pixel position in nametable memory. For more information, 
; see "The Skinny on NES Scrolling" by loopy, available from the main site. 
;--------------------------------------------------------
PPU_ADDR   = $2006 ; Sets VRAM address in PPU


;--------------------------------------------------------
; VRAM data register (r/w)
;
; When the screen is turned off in PPUMASK or during vertical blank, 
; read or write data from VRAM through this port.
;
; Reads are delayed by one cycle; discard the first byte read. Do not 
; attempt to access this register while the PPU is rendering; if you do, 
; Bad Things^(TM) will happen (i.e. graphical glitches and RAM corruption). 
;--------------------------------------------------------
PPU_DATA   = $2007 ; Writes data to current VRAM address

;--------------------------------------------------------
; MMC3 registers
;
; No doc yet, must check wiki
;--------------------------------------------------------
MMC3_CTRL        = $8000
MMC3_PAGE        = $8001
MMC3_MIRROR      = $A000
MMC3_SRAM        = $A001
MMC3_IRQ_COUNTER = $C000
MMC3_IRQ_RELOAD  = $C001
MMC3_IRQ_DISABLE = $E000
MMC3_IRQ_ENABLE  = $E001

MMC3_MIRROR_V =	0
MMC3_MIRROR_H =	1

MMC3_SRAM_DISABLE = 0
MMC3_SRAM_ENABLE  = 1

;------------------------
; Common memory addresses
OAM               = $0400

; Sprite DMA
SPR_DMA           = $4014

; Joypads related
JOYPAD_PORT1      = $4016
JOYPAD_PORT2      = $4017

BTN_A             = %10000000
BTN_B             = %01000000
BTN_SELECT        = %00100000
BTN_START         = %00010000
BTN_UP            = %00001000
BTN_DOWN          = %00000100
BTN_LEFT          = %00000010
BTN_RIGHT         = %00000001

; Sound related
APU_REGISTER      = $4000
APU_SQUARE1       = $4000
APU_SQUARE2       = $4004
APU_TRIANGLE      = $4008
APU_NOISE         = $400C
APU_DELTA         = $4010
APU_MASTERCTRL    = $4015
APU_FRAMECOUNTER  = $4017   ; Note: same as joy 2

; flags
APU_FRAMECOUNTER_IRQ_CLEAR = %01000000


;--------------------------------------------------------
; Sprites attributes:
;76543210
;||||||||
;||||||++- Palette (4 to 7) of sprite
;|||+++--- Unimplemented, reads back as 0
;||+------ Priority (0: in front of background; 1: behind background)
;|+------- Flip sprite horizontally
;+-------- Flip sprite vertically
;--------------------------------------------------------
SPR_PRIORITY_BACK   = %00100000 ; The sprite priority is behind background
SPR_PRIORITY_FRONT  = %00000000 ; The sprite priority is in front of background
SPR_FLIP_HORIZONTAL = %01000000 ; The sprite is flipped horizontally
SPR_FLIP_VERTIAL    = %10000000 ; The sprite is flipped vertically