#include "ppu.h" /* Copyright (c) 2021 Devine Lu Linvega Copyright (c) 2021 Andrew Alderwick Permission to use, copy, modify, and distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies. THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE. */ static Uint8 blending[5][16] = { {0, 0, 0, 0, 1, 0, 1, 1, 2, 2, 0, 2, 3, 3, 3, 0}, {0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3}, {1, 2, 3, 1, 1, 2, 3, 1, 1, 2, 3, 1, 1, 2, 3, 1}, {2, 3, 1, 2, 2, 3, 1, 2, 2, 3, 1, 2, 2, 3, 1, 2}, {1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0}}; static void ppu_clear(Ppu *p) { int x, y; for(y = 0; y < p->height; ++y) { for(x = 0; x < p->width; ++x) { ppu_pixel(p, p->bg, x, y, 0); ppu_pixel(p, p->fg, x, y, 0); } } } int ppu_pixel(Ppu *p, Uint8 *layer, Uint16 x, Uint16 y, Uint8 color) { int row = (y % 8) + ((x / 8 + y / 8 * p->width / 8) * 16), col = x % 8, ret; Uint8 w; if(x >= p->width || y >= p->height) return 0; w = layer[row]; if(color == 0 || color == 2) layer[row] &= ~(1UL << (7 - col)); else layer[row] |= 1UL << (7 - col); ret = w ^ layer[row]; w = layer[row + 8]; if(color == 0 || color == 1) layer[row + 8] &= ~(1UL << (7 - col)); else layer[row + 8] |= 1UL << (7 - col); return ret | (w ^ layer[row + 8]); } int ppu_1bpp(Ppu *p, Uint8 *layer, Uint16 x, Uint16 y, Uint8 *sprite, Uint8 color, Uint8 flipx, Uint8 flipy) { Uint16 v, h; int ret = 0; for(v = 0; v < 8; v++) for(h = 0; h < 8; h++) { Uint8 ch1 = (sprite[v] >> (7 - h)) & 0x1; if(ch1 || blending[4][color]) ret |= ppu_pixel(p, layer, x + (flipx ? 7 - h : h), y + (flipy ? 7 - v : v), blending[ch1][color]); } return ret; } int ppu_2bpp(Ppu *p, Uint8 *layer, Uint16 x, Uint16 y, Uint8 *sprite, Uint8 color, Uint8 flipx, Uint8 flipy) { Uint16 v, h; int ret = 0; for(v = 0; v < 8; v++) for(h = 0; h < 8; h++) { Uint8 ch1 = ((sprite[v] >> (7 - h)) & 0x1); Uint8 ch2 = ((sprite[v + 8] >> (7 - h)) & 0x1); Uint8 ch = ch1 + ch2 * 2; if(ch || blending[4][color]) ret |= ppu_pixel(p, layer, x + (flipx ? 7 - h : h), y + (flipy ? 7 - v : v), blending[ch][color]); } return ret; } /* output */ int ppu_set_size(Ppu *p, Uint16 width, Uint16 height) { /* round width and height up to nearest multiple of 8 */ width = ((width - 1) | 0x7) + 1; height = ((height - 1) | 0x7) + 1; p->width = width; p->height = height; p->bg = realloc(p->bg, p->width / 4 * p->height * sizeof(Uint8)); p->fg = realloc(p->fg, p->width / 4 * p->height * sizeof(Uint8)); ppu_clear(p); return p->bg && p->fg; }