PioneerLDControl.cc

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#include "PioneerLDControl.hh"
#include "CacheLine.hh"
#include "serialize.hh"
#include "LaserdiscPlayer.hh"
#include "MSXPPI.hh"
#include "MSXException.hh"
#include "VDP.hh"
#include "memory.hh"

namespace openmsx {

/*
 * Laserdisc Control: there are three bits involved here. There are three
 * bits/connections involved.
 * - EXTACK (from Laserdisc -> MSX) will remain low for a while to acknowledge
 *   it has received a command and is executing
 * - EXTCONTROL (from MSX -> Laserdisc) one bit information which is used for
 *   sending commands
 * - PULSE (internal to MSX) 8175.5hz signal which used by software to
 *   create the right pulses for communicating with the Laserdisc over
 *   EXTCONTROL.
 *
 * Sound Muting: left and right audio channels from Laserdisc input can
 * be muted independently. After reset or startup both channels are muted.
 * The left muting is controlled by bit 7 of 0x7fff; set is not muted,
 * cleared is muted. If this bit changed from 0->1 (rising edge triggered
 * and inverted) then bit 4 of register C of PPI switches L muting; set
 * for muting disabled, clear for muting enabled.
 *
 * Cassette Input: If the motor relay is OFF then audio on the R channel
 * ends up in the PSG (regardless of muting); if the motor relay is ON
 * then normal tape input is used.
 */
PioneerLDControl::PioneerLDControl(const DeviceConfig& config)
        : MSXDevice(config)
        , rom(getName() + " ROM", "rom", config)
        , clock(EmuTime::zero)
        , irq(getMotherBoard(), "PioneerLDControl.IRQdisplayoff")
        , videoEnabled(false)
{
        if (config.getChildDataAsBool("laserdisc", true)) {
                laserdisc = make_unique<LaserdiscPlayer>(
                        getHardwareConfig(), *this);
        }
        reset(getCurrentTime());
}

void PioneerLDControl::init()
{
        MSXDevice::init();

        const auto& refs = getReferences();
        ppi = refs.size() >= 1 ? dynamic_cast<MSXPPI*>(refs[0]) : nullptr;
        if (!ppi) {
                throw MSXException("Invalid PioneerLDControl configuration: "
                                   "need reference to PPI device.");
        }

        vdp = refs.size() == 2 ? dynamic_cast<VDP*>(refs[1]) : nullptr;
        if (!vdp) {
                throw MSXException("Invalid PioneerLDControl configuration: "
                                   "need reference to VDP device.");
        }
}

PioneerLDControl::~PioneerLDControl() = default;

void PioneerLDControl::reset(EmuTime::param time)
{
        mutel = muter = true;
        superimposing = false;
        extint = false;

        irq.reset();
        if (laserdisc) laserdisc->setMuting(mutel, muter, time);
}

byte PioneerLDControl::readMem(word address, EmuTime::param time)
{
        byte val = PioneerLDControl::peekMem(address, time);
        if (address == 0x7fff) {
                extint = false;
                irq.reset();
        }
        return val;
}

byte PioneerLDControl::peekMem(word address, EmuTime::param time) const
{
        byte val = 0xff;

        if (address == 0x7fff) {
                if (videoEnabled) {
                        val &= 0x7f;
                }
                if (!extint) {
                        val &= 0xfe;
                }
        } else if (address == 0x7ffe) {
                if (clock.getTicksTill(time) & 1) {
                        val &= 0xfe;
                }
                if (laserdisc && laserdisc->extAck(time)) {
                        val &= 0x7f;
                }
        } else if (0x4000 <= address && address < 0x6000) {
                val = rom[address & 0x1fff];
        }
        return val;
}

const byte* PioneerLDControl::getReadCacheLine(word start) const
{
        if ((start & CacheLine::HIGH) == (0x7FFE & CacheLine::HIGH)) {
                return nullptr;
        } else if (0x4000 <= start && start < 0x6000) {
                return &rom[start & 0x1fff];
        } else {
                return unmappedRead;
        }
}

void PioneerLDControl::writeMem(word address, byte value, EmuTime::param time)
{
        if (address == 0x7fff) {
                // superimpose
                superimposing = !(value & 1);
                irq.set(superimposing && extint);

                updateVideoSource();

                // Muting
                if (!mutel && !(value & 0x80)) {
                        muter = !(ppi->peekIO(2, time) & 0x10);
                }
                mutel = !(value & 0x80);
                if (laserdisc) laserdisc->setMuting(mutel, muter, time);

        } else if (address == 0x7ffe) {
                if (laserdisc) laserdisc->extControl(value & 1, time);
        }
}

byte* PioneerLDControl::getWriteCacheLine(word start) const
{
        if ((start & CacheLine::HIGH) == (0x7FFE & CacheLine::HIGH)) {
                return nullptr;
        } else {
                return unmappedWrite;
        }
}

void PioneerLDControl::videoIn(bool enabled)
{
        if (videoEnabled && !enabled) {
                // raise an interrupt when external video goes off
                extint = true;
                if (superimposing) irq.set();
        }
        videoEnabled = enabled;
        updateVideoSource();
}

void PioneerLDControl::updateVideoSource()
{
        auto* videoSource = (videoEnabled && superimposing && laserdisc)
                          ? laserdisc->getRawFrame()
                          : nullptr;
        vdp->setExternalVideoSource(videoSource);
}

template<typename Archive>
void PioneerLDControl::serialize(Archive& ar, unsigned /*version*/)
{
        ar.serialize("clock", clock);
        ar.serialize("mutel", mutel);
        ar.serialize("muter", muter);
        // videoEnabled is restored from LaserdiscPlayer. Set to false
        // for now so that the irq does not get changed during load
        if (ar.isLoader()) {
                videoEnabled = false;
        }
        ar.serialize("superimposing", superimposing);
        ar.serialize("extint", extint);
        ar.serialize("irq", irq);
        if (laserdisc) ar.serialize("laserdisc", *laserdisc);

        if (ar.isLoader()) {
                updateVideoSource();
                if (laserdisc) {
                        laserdisc->setMuting(mutel, muter, getCurrentTime());
                }
        }
}

REGISTER_MSXDEVICE(PioneerLDControl, "PBASIC");
INSTANTIATE_SERIALIZE_METHODS(PioneerLDControl);

} // namespace openmsx