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72 lines
1.8 KiB
C
72 lines
1.8 KiB
C
#include "ppu.h"
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/*
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Copyright (c) 2021 Devine Lu Linvega
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Copyright (c) 2021 Andrew Alderwick
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Permission to use, copy, modify, and distribute this software for any
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purpose with or without fee is hereby granted, provided that the above
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copyright notice and this permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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WITH REGARD TO THIS SOFTWARE.
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*/
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static Uint8 blending[5][16] = {
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{0, 0, 0, 0, 1, 0, 1, 1, 2, 2, 0, 2, 3, 3, 3, 0},
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{0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3},
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{1, 2, 3, 1, 1, 2, 3, 1, 1, 2, 3, 1, 1, 2, 3, 1},
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{2, 3, 1, 2, 2, 3, 1, 2, 2, 3, 1, 2, 2, 3, 1, 2},
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{1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0}};
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void
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ppu_pixel(Ppu *p, Uint8 layer, Uint16 x, Uint16 y, Uint8 color)
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{
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Uint8 *pixel = &p->pixels[y * p->width + x], shift = layer * 2;
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if(x < p->width && y < p->height)
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*pixel = (*pixel & ~(0x3 << shift)) | (color << shift);
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}
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void
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ppu_1bpp(Ppu *p, Uint8 layer, Uint16 x, Uint16 y, Uint8 *sprite, Uint8 color, Uint8 flipx, Uint8 flipy)
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{
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Uint16 v, h;
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for(v = 0; v < 8; v++)
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for(h = 0; h < 8; h++) {
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Uint8 ch1 = (sprite[v] >> (7 - h)) & 0x1;
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if(ch1 || blending[4][color])
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ppu_pixel(p,
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layer,
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x + (flipx ? 7 - h : h),
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y + (flipy ? 7 - v : v),
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blending[ch1][color]);
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}
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}
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void
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ppu_2bpp(Ppu *p, Uint8 layer, Uint16 x, Uint16 y, Uint8 *sprite, Uint8 color, Uint8 flipx, Uint8 flipy)
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{
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Uint16 v, h;
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for(v = 0; v < 8; v++)
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for(h = 0; h < 8; h++) {
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Uint8 ch1 = ((sprite[v] >> (7 - h)) & 0x1);
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Uint8 ch2 = ((sprite[v + 8] >> (7 - h)) & 0x1);
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Uint8 ch = ch1 + ch2 * 2;
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if(ch || blending[4][color])
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ppu_pixel(p,
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layer,
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x + (flipx ? 7 - h : h),
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y + (flipy ? 7 - v : v),
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blending[ch][color]);
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}
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}
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/* output */
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int
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ppu_init(Ppu *p, Uint8 hor, Uint8 ver)
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{
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p->width = 8 * hor;
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p->height = 8 * ver;
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return 1;
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}
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