mirror of https://github.com/bsnes-emu/bsnes.git
118 lines
4.1 KiB
C++
118 lines
4.1 KiB
C++
auto VDP::Background::run(uint8 hoffset, uint9 voffset) -> void {
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output = {};
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switch(vdp.io.mode) {
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case 0b0000: return graphics1(hoffset, voffset);
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case 0b0001: return;
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case 0b0010: return graphics2(hoffset, voffset);
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case 0b0011: return;
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case 0b0100: return;
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case 0b0101: return;
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case 0b0110: return;
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case 0b0111: return;
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case 0b1000: return graphics3(hoffset, voffset, 192);
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case 0b1001: return;
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case 0b1010: return graphics3(hoffset, voffset, 192);
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case 0b1011: return graphics3(hoffset, voffset, 224);
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case 0b1100: return graphics3(hoffset, voffset, 192);
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case 0b1101: return;
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case 0b1110: return graphics3(hoffset, voffset, 240);
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case 0b1111: return graphics3(hoffset, voffset, 192);
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}
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}
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auto VDP::Background::graphics1(uint8 hoffset, uint9 voffset) -> void {
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uint14 nameTableAddress;
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nameTableAddress.bits( 0, 4) = hoffset.bits(3,7);
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nameTableAddress.bits( 5, 9) = voffset.bits(3,7);
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nameTableAddress.bits(10,13) = vdp.io.nameTableAddress;
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uint8 pattern = vdp.vram[nameTableAddress];
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uint14 patternAddress;
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patternAddress.bits( 0, 2) = voffset.bits(0,2);
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patternAddress.bits( 3,10) = pattern;
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patternAddress.bits(11,13) = vdp.io.patternTableAddress;
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uint14 colorAddress; //d5 = 0
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colorAddress.bits(0, 4) = pattern.bits(3,7);
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colorAddress.bits(6,13) = vdp.io.colorTableAddress;
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uint8 color = vdp.vram[colorAddress];
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uint3 index = hoffset ^ 7;
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if(!vdp.vram[patternAddress].bit(index)) {
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output.color = color.bits(0,3);
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} else {
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output.color = color.bits(4,7);
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}
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}
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auto VDP::Background::graphics2(uint8 hoffset, uint9 voffset) -> void {
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uint14 nameTableAddress;
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nameTableAddress.bits( 0, 4) = hoffset.bits(3,7);
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nameTableAddress.bits( 5, 9) = voffset.bits(3,7);
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nameTableAddress.bits(10,13) = vdp.io.nameTableAddress;
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uint8 pattern = vdp.vram[nameTableAddress];
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uint14 patternAddress;
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patternAddress.bits(0, 2) = voffset.bits(0,2);
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patternAddress.bits(3,10) = pattern;
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if(voffset >= 64 && voffset <= 127) patternAddress.bit(11) = vdp.io.patternTableAddress.bit(0);
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if(voffset >= 128 && voffset <= 191) patternAddress.bit(12) = vdp.io.patternTableAddress.bit(1);
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uint14 colorAddress = patternAddress;
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patternAddress.bit(13) = vdp.io.patternTableAddress.bit(2);
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colorAddress.bit(13) = vdp.io.colorTableAddress.bit(7);
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uint8 colorMask = vdp.io.colorTableAddress.bits(0,6) << 1 | 1;
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uint8 color = vdp.vram[colorAddress];
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uint3 index = hoffset ^ 7;
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if(!vdp.vram[patternAddress].bit(index)) {
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output.color = color.bits(0,3);
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} else {
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output.color = color.bits(4,7);
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}
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}
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auto VDP::Background::graphics3(uint8 hoffset, uint9 voffset, uint vlines) -> void {
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if(hoffset < vdp.io.hscroll.bits(0,2)) return;
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if(!vdp.io.horizontalScrollLock || voffset >= 16) hoffset -= vdp.io.hscroll;
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if(!vdp.io.verticalScrollLock || hoffset <= 191) voffset += vdp.io.vscroll;
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uint14 nameTableAddress;
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if(vlines == 192) {
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if(voffset >= 224) voffset -= 224;
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nameTableAddress.bits( 1, 5) = hoffset.bits(3,7);
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nameTableAddress.bits( 6,10) = voffset.bits(3,7);
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nameTableAddress.bits(11,13) = vdp.io.nameTableAddress.bits(1,3);
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} else {
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voffset += 224;
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nameTableAddress.bits( 1, 5) = hoffset.bits(3,7);
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nameTableAddress.bits( 6,11) = voffset.bits(3,8);
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nameTableAddress.bits(12,13) = vdp.io.nameTableAddress.bits(2,3);
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}
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uint16 pattern;
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pattern.byte(0) = vdp.vram[nameTableAddress | 0];
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pattern.byte(1) = vdp.vram[nameTableAddress | 1];
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if(pattern.bit( 9)) hoffset ^= 7; //hflip
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if(pattern.bit(10)) voffset ^= 7; //vflip
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output.palette = pattern.bit(11);
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output.priority = pattern.bit(12);
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uint14 patternAddress;
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patternAddress.bits(2, 4) = voffset.bits(0,2);
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patternAddress.bits(5,13) = pattern.bits(0,8);
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uint3 index = hoffset ^ 7;
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output.color.bit(0) = vdp.vram[patternAddress | 0].bit(index);
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output.color.bit(1) = vdp.vram[patternAddress | 1].bit(index);
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output.color.bit(2) = vdp.vram[patternAddress | 2].bit(index);
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output.color.bit(3) = vdp.vram[patternAddress | 3].bit(index);
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if(output.color == 0) output.priority = 0;
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}
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auto VDP::Background::power() -> void {
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output = {};
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}
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