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◆ main openmsx / src / memory / MSXPac.cc
2.2 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
e8555c89 Andy McCall 1 
#include "MSXPac.hh"
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#include "CacheLine.hh"
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#include "serialize.hh"
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namespace openmsx {
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static constexpr const char* const PAC_Header = "PAC2 BACKUP DATA";
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MSXPac::MSXPac(const DeviceConfig& config)
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	: MSXDevice(config)
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	, sram(getName() + " SRAM", 0x1FFE, config, PAC_Header)
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{
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	reset(EmuTime::dummy());
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}
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void MSXPac::reset(EmuTime /*time*/)
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{
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	sramEnabled = false;
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	r1ffe = r1fff = 0xFF; // TODO check
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}
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byte MSXPac::readMem(uint16_t address, EmuTime /*time*/)
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{
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	address &= 0x3FFF;
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	if (sramEnabled) {
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		if (address < 0x1FFE) {
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			return sram[address];
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		} else if (address == 0x1FFE) {
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			return r1ffe;
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		} else if (address == 0x1FFF) {
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			return r1fff;
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		} else {
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			return 0xFF;
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		}
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	} else {
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		return 0xFF;
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	}
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}
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const byte* MSXPac::getReadCacheLine(uint16_t address) const
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{
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	address &= 0x3FFF;
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	if (sramEnabled) {
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		if (address < (0x1FFE & CacheLine::HIGH)) {
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			return &sram[address];
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		} else if (address == (0x1FFE & CacheLine::HIGH)) {
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			return nullptr;
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		} else {
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			return unmappedRead.data();
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		}
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	} else {
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		return unmappedRead.data();
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	}
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}
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void MSXPac::writeMem(uint16_t address, byte value, EmuTime /*time*/)
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{
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	address &= 0x3FFF;
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	switch (address) {
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		case 0x1FFE:
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			r1ffe = value;
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			checkSramEnable();
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			break;
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		case 0x1FFF:
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			r1fff = value;
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			checkSramEnable();
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			break;
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		default:
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			if (sramEnabled && (address < 0x1FFE)) {
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				sram.write(address, value);
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			}
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	}
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}
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byte* MSXPac::getWriteCacheLine(uint16_t address)
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{
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	address &= 0x3FFF;
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	if (address == (0x1FFE & CacheLine::HIGH)) {
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		return nullptr;
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	}
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	if (sramEnabled && (address < 0x1FFE)) {
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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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void MSXPac::checkSramEnable()
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{
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	bool newEnabled = (r1ffe == 0x4D) && (r1fff == 0x69);
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	if (sramEnabled != newEnabled) {
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		sramEnabled = newEnabled;
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		invalidateDeviceRWCache();
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	}
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}
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template<typename Archive>
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void MSXPac::serialize(Archive& ar, unsigned /*version*/)
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{
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	ar.template serializeBase<MSXDevice>(*this);
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	ar.serialize("SRAM",  sram,
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	             "r1ffe", r1ffe,
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	             "r1fff", r1fff);
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	if constexpr (Archive::IS_LOADER) {
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		checkSramEnable();
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	}
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}
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INSTANTIATE_SERIALIZE_METHODS(MSXPac);
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REGISTER_MSXDEVICE(MSXPac, "PAC");
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} // namespace openmsx