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; Definitions of commonly-used special memory addresses.;; These are commonly called "registers" in online documentation, even though; that feels like a misnomer; these aren't necessarily hardware registers in; the same sense as PC, A, X, Y, and so on. Despite that, I call them; "registers" too, since that's what everyone else calls them.;; I've often named these register definitions in the same way that they're; named in Yoshi's venerable snes.txt document. In some cases (where the; mnemonic is too obscure) I've invented a different name. In particular,; I've changed "ADD" to "ADDR" to reduce possible confusion between "addresses"; and "addition". The original name from Yoshi's doc is still listed in; brackets, like [CGADD], for easy cross-referencing.;; I've also heavily borrowed from Yoshi's descriptions of what these registers; do, though in many cases I've clarified / simplified the descriptions based; on my own understanding, or simply reformatted them a bit.
; $2100: Screen display initialization [INIDISP]; Format: x000bbbb ; x: 0 = screen on, 1 = screen off, bbbb: Brightness ($0-$F).define INIDISP $2100
; $2105: Screen mode register [BGMODE]; abcdefff a: BG4 tile size (0=8x8, 1=16x16).; b: BG3 tile size (0=8x8, 1=16x16).; c: BG2 tile size (0=8x8, 1=16x16).; d: BG1 tile size (0=8x8, 1=16x16).; e: Highest priority for BG3 in MODE 1.; f: MODE definition..define BGMODE $2105
; $2107-210A: BG1-4 VRAM location registers [BGxSC]; xxxxxxab x: Base address; ab: SC size .define BG1SC $2107.define BG2SC $2108.define BG3SC $2109.define BG4SC $210A
; $210B: BG1 & BG2 VRAM location register [BG12NBA]; $210C: BG3 & BG4 VRAM location register [BG34NBA]; aaaabbbb a: Base address for BG2 (or BG4).; b: Base address for BG1 (or BG3)..define BG12NBA $210B.define BG34NBA $210C
; BG1 horizontal scroll offset. [BG1HOFS]; BG1 vertical scroll offset. [BG1VOFS]; ... and similar registers for BG2-4.; Write to all of these twice, as they want 2 bytes of data.; mmmmmaaa aaaaaaaa a: Horizontal offset.; m: Only set with MODE 7..define BG1HOFS $210D.define BG1VOFS $210E.define BG2HOFS $210F.define BG2VOFS $2110.define BG3HOFS $2111.define BG3VOFS $2112.define BG4HOFS $2113.define BG4VOFS $2114
; $2115: Video port control [VMAIN]; i000abcd i: 0 = Address increment after writing to $2118 or reading; from $2139.; 1 = Address increment after writing to $2119 or reading; from $213A.; ab: Full graphic (see table below).; cd: SC increment (see table below).;; abcd Result; 0100 Increment by 8 for 32 times (2-bit formation).; 1000 Increment by 8 for 64 times (4-bit formation).; 1100 Increment by 8 for 128 times (8-bit formation).; 0000 Address increments 1x1.; 0001 Address increments 32x32.; 0010 Address increments 64x64.; 0011 Address increments 128x128..define VMAIN $2115
; $2116-$2117: Video port address. 2 bytes. [VMADDL/VMADDH].define VMADDR $2116
; $2118-$2119: Video port data. 2 bytes. [VMDATAL/VMDATAH]; According to bit 7 of VMAIN, the data can be stored as:; Bit 7; 0 Write to $2118 only. Lower 8-bits written then; address is increased.; 0 Write to $2119 then $2118. Address increased when both; are written to (in order).; 1 Write to $2119 only. Upper 8-bits written, then; address is increased.; 1 Write to $2118 then $2119. Address increased when both; are written to (in order)..define VMDATA $2118
; $2121: Color palette selection register [CGADD]; Entry 0 corresponds to the SNES background color..define CGADDR $2121
; $2122: Color data register [CGDATA]; The palette color format is 15-bit: [0bbbbbgg][gggrrrrr].; You will typically write to this register twice in a row: first for the; low-order byte (containing green and red) and then for the high-order byte; (containing blue and green)..define CGDATA $2122
; $212C: Main screen designation [TM]; 000abcde a: OBJ/OAM disable/enable.; b: Disable/enable BG4.; c: Disable/enable BG3.; d: Disable/enable BG2.; e: Disable/enable BG1..define MSENABLE $212C
; $4200: Counter enable [NMITIMEN]; n-vh---j n: NMI interrupt enable v: vertical counter enable; h: horizontal counter enable j: joypad enable.define NMITIMEN $4200
; $420B: DMA enable [MDMAEN]; Each bit that's set enables one channel: 76543210.define DMAENABLE $420B
; $4218: Joypad #1 status [JOY1L]; Format: AXLR0000.define JOY1L $4218
; $4219: Joypad #1 status [JOY1H]; Format: BYsSudlr (s=select, S=start, udlr = joypad).define JOY1H $4219
; $421A: Joypad #2 status [JOY2L]; Format: AXLR0000.define JOY2L $421A
; $421B: Joypad #2 status [JOY2H]; Format: BYsSudlr (s=select, S=start, udlr = joypad).define JOY2H $421B
; $43x0: DMA control for channel x. [DMAPX]; vh0cbaaa v: 0 = CPU memory -> PPU.; 1 = PPU -> CPU memory.; h: For HDMA only:; 0 = Absolute addressing.; 1 = Indirect addressing.; c: 0 = Auto address inc/decrement.; 1 = Fixed address (for VRAM, etc.).; b: 0 = Automatic increment.; 1 = Automatic decrement.; a: Transfer type:; 000 = 1 address write twice: LH.; 001 = 2 addresses: LH.; 010 = 1 address write once.; 011 = 2 addresses write twice: LLHH; 100 = 4 addresses: LHLH.define DMA0CTRL $4300
; $43x1: DMA destination for channel x. [BBADX]; The upper byte is assumed to be $21, so the possible destinations are; $2100-$21FF..define DMA0DST $4301
; $43x2-$43x3: DMA source address for channel x. 2 bytes. [AITXL/AITXH].define DMA0SRC $4302
; $43x4: DMA source bank for channel x [AIBX].define DMA0SRCBANK $4304
; $43x5: DMA transfer size & HDMA address. 2 bytes. [DASXL/DASXH]; When using DMA, $43x5 defines the # of bytes to be transferred via DMA; itself. When using HDMA, $43x5 defines the data address ($43x5 = low byte,; $43x6 = hi byte)..define DMA0SIZE $4305
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