mirror of https://github.com/bsnes-emu/bsnes.git
135 lines
3.5 KiB
C++
135 lines
3.5 KiB
C++
#ifdef PPU_CPP
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//OB attributes:
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//0x80: 0 = OBJ above BG, 1 = BG above OBJ
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//0x40: vertical flip
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//0x20: horizontal flip
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//0x10: palette#
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void PPU::dmg_read_tile(bool select, unsigned x, unsigned y, unsigned& data) {
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unsigned tmaddr = 0x1800 + (select << 10), tdaddr;
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tmaddr += (((y >> 3) << 5) + (x >> 3)) & 0x03ff;
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if(status.bg_tiledata_select == 0) {
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tdaddr = 0x1000 + ((int8)vram[tmaddr] << 4);
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} else {
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tdaddr = 0x0000 + (vram[tmaddr] << 4);
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}
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tdaddr += (y & 7) << 1;
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data = vram[tdaddr + 0] << 0;
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data |= vram[tdaddr + 1] << 8;
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}
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void PPU::dmg_scanline() {
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px = 0;
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const unsigned Height = (status.ob_size == 0 ? 8 : 16);
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sprites = 0;
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//find first ten sprites on this scanline
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for(unsigned n = 0; n < 40 * 4; n += 4) {
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Sprite& s = sprite[sprites];
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s.y = oam[n + 0] - 16;
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s.x = oam[n + 1] - 8;
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s.tile = oam[n + 2] & ~status.ob_size;
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s.attr = oam[n + 3];
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s.y = status.ly - s.y;
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if(s.y >= Height) continue;
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if(s.attr & 0x40) s.y ^= (Height - 1);
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unsigned tdaddr = (s.tile << 4) + (s.y << 1);
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s.data = vram[tdaddr + 0] << 0;
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s.data |= vram[tdaddr + 1] << 8;
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if(s.attr & 0x20) s.data = hflip(s.data);
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if(++sprites == 10) break;
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}
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//sort by X-coordinate
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for(unsigned lo = 0; lo < sprites; lo++) {
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for(unsigned hi = lo + 1; hi < sprites; hi++) {
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if(sprite[hi].x < sprite[lo].x) std::swap(sprite[lo], sprite[hi]);
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}
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}
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}
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void PPU::dmg_run() {
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bg.color = 0;
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bg.palette = 0;
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ob.color = 0;
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ob.palette = 0;
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unsigned color = 0;
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if(status.display_enable) {
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if(status.bg_enable) dmg_run_bg();
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if(status.window_display_enable) dmg_run_window();
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if(status.ob_enable) dmg_run_ob();
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if(ob.palette == 0) {
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color = bg.color;
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} else if(bg.palette == 0) {
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color = ob.color;
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} else if(ob.priority) {
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color = ob.color;
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} else {
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color = bg.color;
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}
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}
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uint32* output = screen + status.ly * 160 + px++;
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*output = color;
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interface->lcdOutput(color); //Super Game Boy notification
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}
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void PPU::dmg_run_bg() {
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unsigned scrolly = (status.ly + status.scy) & 255;
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unsigned scrollx = (px + status.scx) & 255;
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unsigned tx = scrollx & 7;
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if(tx == 0 || px == 0) dmg_read_tile(status.bg_tilemap_select, scrollx, scrolly, background.data);
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unsigned index = 0;
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index |= (background.data & (0x0080 >> tx)) ? 1 : 0;
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index |= (background.data & (0x8000 >> tx)) ? 2 : 0;
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bg.color = bgp[index];
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bg.palette = index;
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}
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void PPU::dmg_run_window() {
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unsigned scrolly = status.ly - status.wy;
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unsigned scrollx = px + 7 - status.wx;
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if(scrolly >= 144u) return; //also matches underflow (scrolly < 0)
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if(scrollx >= 160u) return; //also matches underflow (scrollx < 0)
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unsigned tx = scrollx & 7;
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if(tx == 0 || px == 0) dmg_read_tile(status.window_tilemap_select, scrollx, scrolly, window.data);
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unsigned index = 0;
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index |= (window.data & (0x0080 >> tx)) ? 1 : 0;
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index |= (window.data & (0x8000 >> tx)) ? 2 : 0;
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bg.color = bgp[index];
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bg.palette = index;
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}
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void PPU::dmg_run_ob() {
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//render backwards, so that first sprite has priority
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for(signed n = sprites - 1; n >= 0; n--) {
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Sprite& s = sprite[n];
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signed tx = px - s.x;
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if(tx < 0 || tx > 7) continue;
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unsigned index = 0;
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index |= (s.data & (0x0080 >> tx)) ? 1 : 0;
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index |= (s.data & (0x8000 >> tx)) ? 2 : 0;
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if(index == 0) continue;
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ob.color = obp[(bool)(s.attr & 0x10)][index];
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ob.palette = index;
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ob.priority = !(s.attr & 0x80);
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}
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}
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#endif
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