mirror of https://github.com/bsnes-emu/bsnes.git
93 lines
2.5 KiB
C++
93 lines
2.5 KiB
C++
//MMC2
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struct NES_PxROM : Board {
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NES_PxROM(Markup::Node& document) : Board(document) {
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revision = Revision::PNROM;
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}
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auto readPRG(uint addr) -> uint8 {
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if(addr < 0x6000) return cpu.mdr();
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if(addr < 0x8000) return prgram.read(addr);
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uint bank = 0;
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switch((addr / 0x2000) & 3) {
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case 0: bank = prgBank; break;
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case 1: bank = 0x0d; break;
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case 2: bank = 0x0e; break;
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case 3: bank = 0x0f; break;
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}
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return prgrom.read((bank * 0x2000) | (addr & 0x1fff));
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}
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auto writePRG(uint addr, uint8 data) -> void {
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if(addr < 0x6000) return;
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if(addr < 0x8000) return prgram.write(addr, data);
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switch(addr & 0xf000) {
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case 0xa000: prgBank = data & 0x0f; break;
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case 0xb000: chrBank[0][0] = data & 0x1f; break;
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case 0xc000: chrBank[0][1] = data & 0x1f; break;
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case 0xd000: chrBank[1][0] = data & 0x1f; break;
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case 0xe000: chrBank[1][1] = data & 0x1f; break;
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case 0xf000: mirror = data & 0x01; break;
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}
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}
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auto addrCIRAM(uint addr) const -> uint {
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switch(mirror) {
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case 0: return ((addr & 0x0400) >> 0) | (addr & 0x03ff); //vertical mirroring
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case 1: return ((addr & 0x0800) >> 1) | (addr & 0x03ff); //horizontal mirroring
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}
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}
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auto readCHR(uint addr) -> uint8 {
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if(addr & 0x2000) return ppu.readCIRAM(addrCIRAM(addr));
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bool region = addr & 0x1000;
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uint bank = chrBank[region][latch[region]];
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if((addr & 0x0ff8) == 0x0fd8) latch[region] = 0;
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if((addr & 0x0ff8) == 0x0fe8) latch[region] = 1;
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return Board::readCHR((bank * 0x1000) | (addr & 0x0fff));
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}
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auto writeCHR(uint addr, uint8 data) -> void {
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if(addr & 0x2000) return ppu.writeCIRAM(addrCIRAM(addr), data);
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bool region = addr & 0x1000;
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uint bank = chrBank[region][latch[region]];
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if((addr & 0x0ff8) == 0x0fd8) latch[region] = 0;
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if((addr & 0x0ff8) == 0x0fe8) latch[region] = 1;
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return Board::writeCHR((bank * 0x1000) | (addr & 0x0fff), data);
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}
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auto power() -> void {
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prgBank = 0;
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chrBank[0][0] = 0;
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chrBank[0][1] = 0;
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chrBank[1][0] = 0;
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chrBank[1][1] = 0;
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mirror = 0;
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latch[0] = 0;
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latch[1] = 0;
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}
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auto serialize(serializer& s) -> void {
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Board::serialize(s);
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s.integer(prgBank);
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s.integer(chrBank[0][0]);
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s.integer(chrBank[0][1]);
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s.integer(chrBank[1][0]);
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s.integer(chrBank[1][1]);
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s.integer(mirror);
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s.array(latch);
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}
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enum Revision : uint {
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PEEOROM,
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PNROM,
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} revision;
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uint4 prgBank;
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uint5 chrBank[2][2];
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bool mirror;
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bool latch[2];
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};
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