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◆ main openmsx / src / laserdisc / PioneerLDControl.cc
5.1 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
e8555c89 Andy McCall 1 
#include "PioneerLDControl.hh"
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#include "CacheLine.hh"
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#include "MSXException.hh"
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#include "MSXPPI.hh"
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#include "VDP.hh"
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#include "serialize.hh"
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namespace openmsx {
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/*
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 * Laserdisc Control: there are three bits involved here. There are three
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 * bits/connections involved.
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 * - EXTACK (from Laserdisc -> MSX) will remain low for a while to acknowledge
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 *   it has received a command and is executing
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 * - EXTCONTROL (from MSX -> Laserdisc) one bit information which is used for
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 *   sending commands
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 * - PULSE (internal to MSX) 8175.5hz signal which used by software to
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 *   create the right pulses for communicating with the Laserdisc over
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 *   EXTCONTROL.
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 *
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 * Sound Muting: left and right audio channels from Laserdisc input can
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 * be muted independently. After reset or startup both channels are muted.
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 * The left muting is controlled by bit 7 of 0x7fff; set is not muted,
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 * cleared is muted. If this bit changed from 0->1 (rising edge triggered
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 * and inverted) then bit 4 of register C of PPI switches L muting; set
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 * for muting disabled, clear for muting enabled.
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 *
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 * Cassette Input: If the motor relay is OFF then audio on the R channel
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 * ends up in the PSG (regardless of muting); if the motor relay is ON
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 * then normal tape input is used.
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 */
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PioneerLDControl::PioneerLDControl(DeviceConfig& config)
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	: MSXDevice(config)
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	, rom(getName() + " ROM", "rom", config)
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	, irq(getMotherBoard(), "PioneerLDControl.IRQdisplayoff")
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{
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	if (config.getChildDataAsBool("laserdisc", true)) {
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		laserdisc.emplace(getHardwareConfig(), *this);
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	}
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}
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void PioneerLDControl::init()
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{
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	MSXDevice::init();
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	const auto& refs = getReferences();
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	ppi = !refs.empty() ? dynamic_cast<MSXPPI*>(refs[0]) : nullptr;
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	if (!ppi) {
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		throw MSXException("Invalid PioneerLDControl configuration: "
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		                   "need reference to PPI device.");
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	}
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	vdp = refs.size() == 2 ? dynamic_cast<VDP*>(refs[1]) : nullptr;
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	if (!vdp) {
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		throw MSXException("Invalid PioneerLDControl configuration: "
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		                   "need reference to VDP device.");
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	}
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	reset(getCurrentTime());
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}
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PioneerLDControl::~PioneerLDControl() = default;
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void PioneerLDControl::reset(EmuTime time)
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{
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	muteL = muteR = true;
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	superimposing = false;
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	extInt = false;
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	irq.reset();
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	if (laserdisc) laserdisc->setMuting(muteL, muteR, time);
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}
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byte PioneerLDControl::readMem(uint16_t address, EmuTime time)
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{
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	byte val = PioneerLDControl::peekMem(address, time);
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	if (address == 0x7fff) {
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		extInt = false;
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		irq.reset();
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	}
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	return val;
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}
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byte PioneerLDControl::peekMem(uint16_t address, EmuTime time) const
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{
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	byte val = 0xff;
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	if (address == 0x7fff) {
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		if (videoEnabled) {
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			val &= 0x7f;
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		}
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		if (!extInt) {
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			val &= 0xfe;
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		}
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	} else if (address == 0x7ffe) {
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		if (clock.getTicksTill(time) & 1) {
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			val &= 0xfe;
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		}
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		if (laserdisc && laserdisc->extAck(time)) {
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			val &= 0x7f;
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		}
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	} else if (0x4000 <= address && address < 0x6000) {
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		val = rom[address & 0x1fff];
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	}
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	return val;
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}
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const byte* PioneerLDControl::getReadCacheLine(uint16_t address) const
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{
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	if ((address & CacheLine::HIGH) == (0x7FFE & CacheLine::HIGH)) {
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		return nullptr;
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	} else if (0x4000 <= address && address < 0x6000) {
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		return &rom[address & 0x1fff];
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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 PioneerLDControl::writeMem(uint16_t address, byte value, EmuTime time)
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{
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	if (address == 0x7fff) {
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		// superimpose
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		superimposing = !(value & 1);
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		irq.set(superimposing && extInt);
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		updateVideoSource();
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		// Muting
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		if (!muteL && !(value & 0x80)) {
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			muteR = !(ppi->peekIO(2, time) & 0x10);
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		}
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		muteL = !(value & 0x80);
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		if (laserdisc) laserdisc->setMuting(muteL, muteR, time);
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	} else if (address == 0x7ffe) {
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		if (laserdisc) laserdisc->extControl(value & 1, time);
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	}
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}
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byte* PioneerLDControl::getWriteCacheLine(uint16_t address)
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{
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	if ((address & CacheLine::HIGH) == (0x7FFE & CacheLine::HIGH)) {
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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 PioneerLDControl::videoIn(bool enabled)
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{
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	if (videoEnabled && !enabled) {
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		// raise an interrupt when external video goes off
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		extInt = true;
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		if (superimposing) irq.set();
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	}
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	videoEnabled = enabled;
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	updateVideoSource();
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}
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void PioneerLDControl::updateVideoSource()
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{
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	const auto* videoSource = (videoEnabled && superimposing && laserdisc)
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	                        ? laserdisc->getRawFrame()
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	                        : nullptr;
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	vdp->setExternalVideoSource(videoSource);
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}
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template<typename Archive>
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void PioneerLDControl::serialize(Archive& ar, unsigned /*version*/)
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{
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	ar.serialize("clock", clock,
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	             "mutel", muteL,
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	             "muter", muteR);
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	// videoEnabled is restored from LaserdiscPlayer. Set to false
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	// for now so that the irq does not get changed during load
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	if constexpr (Archive::IS_LOADER) {
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		videoEnabled = false;
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	}
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	ar.serialize("superimposing", superimposing,
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	             "extint",        extInt,
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	             "irq",           irq);
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	if (laserdisc) ar.serialize("laserdisc", *laserdisc);
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	if constexpr (Archive::IS_LOADER) {
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		updateVideoSource();
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		if (laserdisc) {
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			laserdisc->setMuting(muteL, muteR, getCurrentTime());
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		}
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	}
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}
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REGISTER_MSXDEVICE(PioneerLDControl, "PBASIC");
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INSTANTIATE_SERIALIZE_METHODS(PioneerLDControl);
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} // namespace openmsx