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◆ main openmsx / src / sound / MSXMoonSound.cc
4.2 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
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#include "MSXMoonSound.hh"
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#include "serialize.hh"
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#include "one_of.hh"
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#include <type_traits>
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namespace openmsx {
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static size_t getRamSize(const DeviceConfig& config)
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{
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	int ramSizeInKb = config.getChildDataAsInt("sampleram", 512);
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	if (ramSizeInKb != one_of(
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		   0,     //
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		 128,     // 128kB
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		 256,     // 128kB  128kB
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		 512,     // 512kB
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		 640,     // 512kB  128kB
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		1024,     // 512kB  512kB
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		2048)) {  // 512kB  512kB  512kB  512kB
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		throw MSXException(
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			"Wrong sample RAM size for MoonSound's YMF278. "
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			"Got ", ramSizeInKb, ", but must be one of "
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			"0, 128, 256, 512, 640, 1024 or 2048.");
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	}
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	return size_t(ramSizeInKb) * 1024; // kilo-bytes -> bytes
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}
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static void setupMemPtrs(bool mode0, std::span<const uint8_t> rom, std::span<const uint8_t> ram,
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                         std::span<YMF278::Block128, 32> memPtrs)
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{
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	// /MCS0: connected to a 2MB ROM chip
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	// For RAM there are multiple possibilities (but they all use /MCS6../MCS9)
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	// * 128kB:
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	//   1 SRAM chip of 128kB, chip enable (/CE) of this SRAM chip is connected to
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	//   the 1Y0 output of a 74LS139 (2-to-4 decoder). The enable input of the
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	//   74LS139 is connected to YMF278 pin /MCS6 and the 74LS139 1B:1A inputs are
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	//   connected to YMF278 pins MA18:MA17. So the SRAM is selected when /MC6 is
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	//   active and MA18:MA17 == 0:0.
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	// * 256kB:
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	//   2 SRAM chips of 128kB. First one connected as above. Second one has /CE
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	//   connected to 74LS139 pin 1Y1. So SRAM2 is selected when /MSC6 is active
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	//   and MA18:MA17 == 0:1.
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	// * 512kB:
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	//   1 SRAM chip of 512kB, /CE connected to /MCS6
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	// * 640kB:
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	//   1 SRAM chip of 512kB, /CE connected to /MCS6
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	//   1 SRAM chip of 128kB, /CE connected to /MCS7.
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	//     (This means SRAM2 is mirrored over a 512kB region)
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	// * 1024kB:
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	//   1 SRAM chip of 512kB, /CE connected to /MCS6
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	//   1 SRAM chip of 512kB, /CE connected to /MCS7
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	// * 2048kB:
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	//   1 SRAM chip of 512kB, /CE connected to /MCS6
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	//   1 SRAM chip of 512kB, /CE connected to /MCS7
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	//   1 SRAM chip of 512kB, /CE connected to /MCS8
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	//   1 SRAM chip of 512kB, /CE connected to /MCS9
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	//   This configuration is not so easy to create on the v2.0 PCB. So it's
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	//   very rare.
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	// /MCS1../MCS5: unused
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	static constexpr auto k128 = YMF278::k128;
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	// first 2MB, ROM, both mode0 and mode1
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	for (auto i : xrange(16)) {
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		memPtrs[i] = subspan<k128>(rom, i * k128);
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	}
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	auto ramPart = [&](int i) {
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		return (ram.size() >= (i + 1) * k128)
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			? subspan<k128>(ram, i * k128)
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			: YMF278::Block128{};
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	};
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	if (mode0) [[likely]] {
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		// second 2MB, RAM, as much as if available, upto 2MB
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		for (auto i : xrange(16)) {
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			memPtrs[i + 16] = ramPart(i);
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		}
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	} else {
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		// mode1, normally this shouldn't be used on MoonSound
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		for (auto i : xrange(12)) {
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			memPtrs[i + 16] = YMF278::Block128{};
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		}
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		for (auto i : xrange(4)) {
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			memPtrs[i + 28] = ramPart(i);
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		}
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	}
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}
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MSXMoonSound::MSXMoonSound(DeviceConfig& config)
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	: MSXDevice(config)
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	, ymf278b(getName(), getRamSize(config), config, setupMemPtrs, getCurrentTime())
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{
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	powerUp(getCurrentTime());
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}
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void MSXMoonSound::powerUp(EmuTime time)
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{
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	ymf278b.powerUp(time);
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}
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void MSXMoonSound::reset(EmuTime time)
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{
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	ymf278b.reset(time);
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}
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byte MSXMoonSound::readIO(uint16_t port, EmuTime time)
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{
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	return ymf278b.readIO(port, time);
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}
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byte MSXMoonSound::peekIO(uint16_t port, EmuTime time) const
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{
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	return ymf278b.peekIO(port, time);
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}
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void MSXMoonSound::writeIO(uint16_t port, byte value, EmuTime time)
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{
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	ymf278b.writeIO(port, value, time);
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}
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// version 1: initial version
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// version 2: added alreadyReadID
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// version 3: moved loadTime and busyTime from YMF278 to here
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//            removed alreadyReadID
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// version 4: moved (most) state to YMF278B
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template<typename Archive>
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void MSXMoonSound::serialize(Archive& ar, unsigned version)
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{
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	ar.template serializeBase<MSXDevice>(*this);
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	if (ar.versionAtLeast(version, 4)) {
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		ar.serialize("ymf278b", ymf278b);
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	} else {
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		assert(Archive::IS_LOADER);
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		if constexpr (std::is_same_v<Archive, XmlInputArchive>) {
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			ymf278b.serialize_bw_compat(
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				static_cast<XmlInputArchive&>(ar), version, getCurrentTime());
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		} else {
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			assert(false);
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		}
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	}
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}
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INSTANTIATE_SERIALIZE_METHODS(MSXMoonSound);
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REGISTER_MSXDEVICE(MSXMoonSound, "MoonSound");
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} // namespace openmsx