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◆ main openmsx / src / memory / RomKonamiSCC.cc
4.0 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
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// KONAMI 8kB cartridges with SCC
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//
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// this type is used by Konami cartridges that do have an SCC and some others
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// examples of cartridges: Nemesis 2, Nemesis 3, King's Valley 2, Space Manbow
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// Solid Snake, Quarth, Ashguine 1, Animal, Arkanoid 2, ...
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// Those last 3 were probably modified ROM images, they should be ASCII8
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//
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// The address to change banks:
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//  bank 1: 0x5000 - 0x57ff (0x5000 used)
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//  bank 2: 0x7000 - 0x77ff (0x7000 used)
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//  bank 3: 0x9000 - 0x97ff (0x9000 used)
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//  bank 4: 0xB000 - 0xB7ff (0xB000 used)
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#include "RomKonamiSCC.hh"
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#include "CacheLine.hh"
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#include "MSXCliComm.hh"
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#include "MSXMotherBoard.hh"
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#include "serialize.hh"
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#include "xrange.hh"
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namespace openmsx {
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RomKonamiSCC::RomKonamiSCC(const DeviceConfig& config, Rom&& rom_)
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	: Rom8kBBlocks(config, std::move(rom_))
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	, scc(getName() + " SCC", config, getCurrentTime())
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{
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	// warn if a ROM is used that would not work on a real KonamiSCC mapper
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	if (rom.size() > 512 * 1024) {
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		getMotherBoard().getMSXCliComm().printWarning(
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			"The size of this ROM image is larger than 512kB, "
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			"which is not supported on real Konami SCC mapper "
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			"chips!");
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	}
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	powerUp(getCurrentTime());
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}
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void RomKonamiSCC::powerUp(EmuTime time)
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{
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	scc.powerUp(time);
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	reset(time);
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}
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void RomKonamiSCC::bankSwitch(unsigned page, unsigned block)
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{
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	setRom(page, block);
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	// Note: the mirror behavior is different from RomKonami !
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	if (page == 2 || page == 3) {
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		// [0x4000-0x8000), mirrored in [0xC000-0x10000)
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		setRom(page + 4, block);
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	} else if (page == 4 || page == 5) {
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		// [0x8000-0xC000), mirrored in [0x0000-0x4000)
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		setRom(page - 4, block);
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	} else {
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		assert(false);
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	}
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}
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void RomKonamiSCC::reset(EmuTime time)
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{
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	for (auto i : xrange(2, 6)) {
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		bankSwitch(i, i - 2);
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	}
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	sccEnabled = false;
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	scc.reset(time);
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}
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byte RomKonamiSCC::peekMem(uint16_t address, EmuTime time) const
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{
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	if (sccEnabled && (0x9800 <= address) && (address < 0xA000)) {
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		return scc.peekMem(narrow_cast<uint8_t>(address & 0xFF), time);
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	} else {
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		return Rom8kBBlocks::peekMem(address, time);
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	}
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}
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byte RomKonamiSCC::readMem(uint16_t address, EmuTime time)
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{
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	if (sccEnabled && (0x9800 <= address) && (address < 0xA000)) {
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		return scc.readMem(narrow_cast<uint8_t>(address & 0xFF), time);
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	} else {
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		return Rom8kBBlocks::readMem(address, time);
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	}
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}
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const byte* RomKonamiSCC::getReadCacheLine(uint16_t address) const
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{
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	if (sccEnabled && (0x9800 <= address) && (address < 0xA000)) {
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		// don't cache SCC
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		return nullptr;
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	} else {
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		return Rom8kBBlocks::getReadCacheLine(address);
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	}
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}
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void RomKonamiSCC::writeMem(uint16_t address, byte value, EmuTime time)
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{
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	if ((address < 0x5000) || (address >= 0xC000)) {
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		return;
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	}
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	if (sccEnabled && (0x9800 <= address) && (address < 0xA000)) {
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		// write to SCC
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		scc.writeMem(narrow_cast<uint8_t>(address & 0xFF), value, time);
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		return;
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	}
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	if ((address & 0xF800) == 0x9000) {
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		// SCC enable/disable
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		bool newSccEnabled = ((value & 0x3F) == 0x3F);
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		if (newSccEnabled != sccEnabled) {
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			sccEnabled = newSccEnabled;
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			invalidateDeviceRWCache(0x9800, 0x0800);
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		}
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	}
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	if ((address & 0x1800) == 0x1000) {
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		// page selection
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		auto region = address >> 13;
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		bankSwitch(region, value);
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		if ((region == 4) && sccEnabled) {
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			invalidateDeviceRCache(0x9800, 0x0800);
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		}
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	}
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}
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byte* RomKonamiSCC::getWriteCacheLine(uint16_t address)
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{
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	if ((address < 0x5000) || (address >= 0xC000)) {
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		return unmappedWrite.data();
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	} else if (sccEnabled && (0x9800 <= address) && (address < 0xA000)) {
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		// write to SCC
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		return nullptr;
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	} else if ((address & 0xF800) == (0x9000 & CacheLine::HIGH)) {
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		// SCC enable/disable
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		return nullptr;
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	} else if ((address & 0x1800) == (0x1000 & CacheLine::HIGH)) {
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		// page selection
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		return nullptr;
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	} else {
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		return unmappedWrite.data();
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	}
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}
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template<typename Archive>
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void RomKonamiSCC::serialize(Archive& ar, unsigned /*version*/)
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{
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	ar.template serializeBase<Rom8kBBlocks>(*this);
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	ar.serialize("scc",        scc,
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	             "sccEnabled", sccEnabled);
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}
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INSTANTIATE_SERIALIZE_METHODS(RomKonamiSCC);
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REGISTER_MSXDEVICE(RomKonamiSCC, "RomKonamiSCC");
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} // namespace openmsx