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◆ main openmsx / src / memory / RomWonderKid.cc
1.9 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
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#include "RomWonderKid.hh"
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// Mapper reverse engineered by Omar Cornut.
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// Based on the Wonder Kid game for Game Gear, that is fully MSX compatible.
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//
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// Only 1 register works and reacts to the whole $8000..BFFF address range
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//
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// reg $0000 mem $0000..$3fff -- return page 0
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// reg $0001 mem $0000..$3fff -- "
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//
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// reg $4000 mem $4000..$7fff -- return page 0
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// reg $7fff mem $4000..$7fff -- "
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//
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// reg $7fff mem $8000..$bfff --
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// reg $8000 mem $8000..$bfff ok
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// reg $8001 mem $8000..$bfff ok
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// reg $BFFF mem $8000..$bfff ok
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// reg $C000 mem $8000..$bfff --
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//
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//
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// Restating more simply: Actual Wonder Kid mapper only has a single register
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// which is mirrored across all of 0x8000-0xbfff, and writing to any of the
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// mirrors remaps all of 0x8000-0xbfff. Writing in 0x0000-0x7fff, and
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// 0xc000-... has no effect.
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// 0x0000-0x3fff always shows page 0, as does 0x4000-0x7fff
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// The mapper does not respond to reads in 0xc000-0xffff
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namespace openmsx {
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RomWonderKid::RomWonderKid(const DeviceConfig& config, Rom&& rom_)
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	: Rom16kBBlocks(config, std::move(rom_))
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{
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	reset(EmuTime::dummy());
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}
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void RomWonderKid::reset(EmuTime /*time*/)
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{
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	setRom(0, 0); // fixed
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	setRom(1, 0); // fixed
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	setRom(2, 2); // actually confirmed by Omar
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	setUnmapped(3);
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}
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byte RomWonderKid::peekMem(uint16_t address, EmuTime time) const
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{
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	if (address < 0xC000) {
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		return Rom16kBBlocks::peekMem(address, time);
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	}
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	return 0xff;
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}
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byte RomWonderKid::readMem(uint16_t address, EmuTime time)
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{
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	return peekMem(address, time);
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}
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void RomWonderKid::writeMem(uint16_t address, byte value, EmuTime /*time*/)
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{
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	if ((0x8000 <= address) && (address < 0xC000)) {
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		setRom(2, value);
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	}
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}
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byte* RomWonderKid::getWriteCacheLine(uint16_t address)
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{
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	if ((0x8000 <= 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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REGISTER_MSXDEVICE(RomWonderKid, "RomWonderKid");
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} // namespace openmsx