Colin McMillen
9 years ago
2 changed files with 69 additions and 26 deletions
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49pewpew.asm
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46registers.asm
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; Definitions of commonly-used special memory addresses. |
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; |
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; These are commonly called "registers" in online documentation, even though |
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; that feels like a misnomer; these aren't necessarily hardware registers in |
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; the same sense as PC, A, X, Y, and so on. Despite that, I call them |
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; "registers" too, since that's what everyone else calls them. |
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; |
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; Where possible, I have named these register definitions in the same way that |
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; they're named in Yoshi's venerable snes.txt document. |
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; $2100: Screen display register [INIDISP] |
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; Format: x000bbbb |
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; x: 0 = screen on, 1 = screen off, bbbb: Brightness ($0-$F) |
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.define INIDISP $2100 |
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; $2121: Color palette selection register [CGADD] |
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; Entry 0 corresponds to the SNES background color. |
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.define CGADD $2121 |
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; $2122: Color data register [CGDATA] |
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; The palette color format is 15-bit: [0bbbbbgg][gggrrrrr]. |
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; You will typically write to this register twice in a row: first for the |
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; low-order byte (containing green and red) and then for the high-order byte |
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; (containing blue and green). |
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.define CGDATA $2122 |
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; $4200: Counter enable [NMITIMEN] |
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; n-vh---j n: NMI interrupt enable v: vertical counter enable |
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; h: horizontal counter enable j: joypad enable |
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.define NMITIMEN $4200 |
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; $4218: Joypad #1 status [JOY1L] |
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; Format: AXLR0000 |
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.define JOY1L $4218 |
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; $4219: Joypad #1 status [JOY1H] |
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; Format: BYsSudlr (s=select, S=start, udlr = joypad) |
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.define JOY1H $4219 |
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; $421A: Joypad #2 status [JOY2L] |
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; Format: AXLR0000 |
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.define JOY2L $421A |
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; $421B: Joypad #2 status [JOY2H] |
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; Format: BYsSudlr (s=select, S=start, udlr = joypad) |
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.define JOY2H $421B |
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