mirror of https://github.com/bsnes-emu/bsnes.git
88 lines
2.0 KiB
C++
88 lines
2.0 KiB
C++
auto VDP::Sprite::write(uint9 address, uint16 data) -> void {
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if(address > 320) return;
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auto& object = oam[address >> 2];
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switch(address.bits(0,1)) {
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case 0: {
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object.y = data.bits(0,8);
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break;
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}
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case 1: {
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object.link = data.bits(0,6);
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object.height = 1 + data.bits(8,9) << 3;
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object.width = 1 + data.bits(10,11) << 3;
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break;
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}
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case 2: {
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object.address = data.bits(0,10) << 4;
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object.horizontalFlip = data.bit(11);
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object.verticalFlip = data.bit(12);
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object.palette = data.bits(13,14);
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object.priority = data.bit(15);
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break;
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}
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case 3: {
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object.x = data.bits(0,8);
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break;
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}
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}
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}
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auto VDP::Sprite::scanline(uint y) -> void {
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objects.reset();
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uint7 link = 0;
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uint tiles = 0;
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do {
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auto& object = oam[link];
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link = object.link;
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if(128 + y < object.y) continue;
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if(128 + y >= object.y + object.height) continue;
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if(object.x == 0) break;
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objects.append(object);
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tiles += object.width >> 3;
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} while(link && link < 80 && objects.size() < 20 && tiles < 40);
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}
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auto VDP::Sprite::run(uint x, uint y) -> void {
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output.priority = 0;
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output.color = 0;
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for(auto& o : objects) {
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if(128 + x < o.x) continue;
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if(128 + x >= o.x + o.width) continue;
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uint objectX = 128 + x - o.x;
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uint objectY = 128 + y - o.y;
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if(o.horizontalFlip) objectX = (o.width - 1) - objectX;
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if(o.verticalFlip) objectY = (o.height - 1) - objectY;
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uint tileX = objectX >> 3;
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uint tileY = objectY >> 3;
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uint tileNumber = tileX * (o.height >> 3) + tileY;
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uint15 tileAddress = o.address + (tileNumber << 4);
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uint pixelX = objectX & 7;
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uint pixelY = objectY & 7;
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tileAddress += pixelY << 1 | pixelX >> 2;
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uint16 tileData = vdp.vram.read(tileAddress);
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uint4 color = tileData >> (((pixelX & 3) ^ 3) << 2);
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if(color) {
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output.color = o.palette << 4 | color;
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output.priority = o.priority;
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break;
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}
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}
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}
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auto VDP::Sprite::power() -> void {
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memory::fill(&io, sizeof(IO));
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}
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