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◆ main openmsx / src / memory / RomAscii16X.cc
2.3 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
e8555c89 Andy McCall 1 
// ASCII-X 16kB cartridges
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//
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// Banks:
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//  first  16kB: 0x4000 - 0x7FFF and 0xC000 - 0xFFFF
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//  second 16kB: 0x8000 - 0xBFFF and 0x0000 - 0x3FFF
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//
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// Address to change banks:
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//  first  16kB: 0x6000 - 0x6FFF, 0xA000 - 0xAFFF, 0xE000 - 0xEFFF, 0x2000 - 0x2FFF
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//  second 16kB: 0x7000 - 0x7FFF, 0xB000 - 0xBFFF, 0xF000 - 0xFFFF, 0x3000 - 0x3FFF
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//
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// 12-bit bank number is composed by address bits 8-11 and the data bits.
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//
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// Backed by FlashROM.
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#include "RomAscii16X.hh"
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#include "narrow.hh"
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#include "outer.hh"
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#include "serialize.hh"
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namespace openmsx {
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RomAscii16X::RomAscii16X(DeviceConfig& config, Rom&& rom_)
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	: MSXRom(config, std::move(rom_))
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	, debuggable(*this)
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	, flash(rom, AmdFlashChip::S29GL064S70TFI040, {}, config)
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{
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	reset(EmuTime::dummy());
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}
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void RomAscii16X::reset(EmuTime /*time*/)
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{
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	ranges::iota(bankRegs, uint16_t(0));
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	flash.reset();
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	invalidateDeviceRCache(); // flush all to be sure
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}
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unsigned RomAscii16X::getFlashAddr(uint16_t addr) const
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{
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	uint16_t bank = bankRegs[((addr >> 14) & 1) ^ 1];
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	return (bank << 14) | (addr & 0x3FFF);
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}
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byte RomAscii16X::readMem(uint16_t addr, EmuTime time)
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{
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	return flash.read(getFlashAddr(addr), time);
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}
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byte RomAscii16X::peekMem(uint16_t addr, EmuTime time) const
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{
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	return flash.peek(getFlashAddr(addr), time);
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}
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const byte* RomAscii16X::getReadCacheLine(uint16_t addr) const
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{
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	return flash.getReadCacheLine(getFlashAddr(addr));
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}
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void RomAscii16X::writeMem(uint16_t addr, byte value, EmuTime time)
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{
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	flash.write(getFlashAddr(addr), value, time);
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	if ((addr & 0x3FFF) >= 0x2000) {
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		const uint16_t index = (addr >> 12) & 1;
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		bankRegs[index] = (addr & 0x0F00) | value;
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		invalidateDeviceRCache(0x4000 ^ (index << 14), 0x4000);
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		invalidateDeviceRCache(0xC000 ^ (index << 14), 0x4000);
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	}
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}
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byte* RomAscii16X::getWriteCacheLine(uint16_t /* addr */)
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{
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	return nullptr; // not cacheable
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}
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unsigned RomAscii16X::Debuggable::readExt(unsigned address)
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{
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	auto& outer = OUTER(RomAscii16X, debuggable);
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	return outer.bankRegs[((address >> 14) & 1) ^ 1];
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}
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template<typename Archive>
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void RomAscii16X::serialize(Archive& ar, unsigned /*version*/)
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{
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	// skip MSXRom base class
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	ar.template serializeBase<MSXDevice>(*this);
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	ar.serialize("flash",       flash,
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	             "bankRegs",    bankRegs);
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}
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INSTANTIATE_SERIALIZE_METHODS(RomAscii16X);
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REGISTER_MSXDEVICE(RomAscii16X, "RomAscii16X");
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} // namespace openmsx