OXYGENHUB
◆ main openmsx / src / memory / RomMatraCompilation.cc
2.0 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
e8555c89 Andy McCall 1 
#include "RomMatraCompilation.hh"
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#include "serialize.hh"
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#include "one_of.hh"
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#include "xrange.hh"
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// This is basically a generic 8kB mapper (Konami like, but without fixed page
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// at 0x4000), with an extra offset register accessible at 0xBA00.
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// The software only writes to 0x5000, 0x6000, 0x8000, 0xA000 to switch mapper
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// page. I took these as unique switching addresses, as some of the compilation
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// software would write to others, causing crashes.
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// It seems that a write of 1 (and probably 0, but the software doesn't do
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// that) to the offset register should be ignored and will disable the mapper
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// switch addresses. Values of 2 or larger written there must be lowered by 2
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// to get the actual offset to use.
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namespace openmsx {
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RomMatraCompilation::RomMatraCompilation(const DeviceConfig& config, Rom&& rom_)
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	: Rom8kBBlocks(config, std::move(rom_))
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{
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	reset(EmuTime::dummy());
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}
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void RomMatraCompilation::reset(EmuTime /*time*/)
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{
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	setUnmapped(0);
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	setUnmapped(1);
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	for (auto i : xrange(2, 6)) {
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		setRom(i, i - 2);
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	}
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	setUnmapped(6);
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	setUnmapped(7);
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	blockOffset = 2;
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}
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void RomMatraCompilation::writeMem(uint16_t address, byte value, EmuTime /*time*/)
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{
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	if (address == 0xBA00) {
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		// write of block offset
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		blockOffset = value;
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		// retro-actively select the blocks for this offset
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		if (blockOffset >= 2) {
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			for (auto i : xrange(2, 6)) {
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				setRom(i, blockNr[i] + blockOffset - 2);
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			}
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		}
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	} else if ((blockOffset >= 2) &&
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		   (address == one_of(0x5000, 0x6000, 0x8000, 0xA000))) {
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		setRom(address >> 13, value + blockOffset - 2);
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	}
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}
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byte* RomMatraCompilation::getWriteCacheLine(uint16_t address)
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{
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	if ((0x5000 <= address) && (address < 0xC000)) {
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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 RomMatraCompilation::serialize(Archive& ar, unsigned /*version*/)
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{
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	ar.template serializeBase<Rom8kBBlocks>(*this);
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	ar.serialize("blockOffset", blockOffset);
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}
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INSTANTIATE_SERIALIZE_METHODS(RomMatraCompilation);
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REGISTER_MSXDEVICE(RomMatraCompilation, "RomMatraCompilation");
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} // namespace openmsx