MSXMidi.cc

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#include "MSXMidi.hh"
#include "MidiInDevice.hh"
#include "MSXCPUInterface.hh"
#include "MSXException.hh"
#include "narrow.hh"
#include "outer.hh"
#include "serialize.hh"
#include "unreachable.hh"
#include "xrange.hh"
#include <cassert>
 
namespace openmsx {
 
// Documented in MSX-Datapack Vol. 3, section 4 (MSX-MIDI), from page 634
static constexpr byte LIMITED_RANGE_VALUE = 0x01; // b0 = "E8" => determines port range
static constexpr byte DISABLED_VALUE      = 0x80; // b7 = EN
 
MSXMidi::MSXMidi(const DeviceConfig& config)
        : MSXDevice(config)
        , MidiInConnector(MSXDevice::getPluggingController(), "MSX-MIDI-in")
        , timerIRQ(getMotherBoard(), MSXDevice::getName() + ".IRQtimer")
        , rxrdyIRQ(getMotherBoard(), MSXDevice::getName() + ".IRQrxrdy")
        , isExternalMSXMIDI(config.findChild("external") != nullptr)
        , isEnabled(!isExternalMSXMIDI)
        , outConnector(MSXDevice::getPluggingController(), "MSX-MIDI-out")
        , i8251(getScheduler(), interface, getCurrentTime())
        , i8254(getScheduler(), &cntr0, nullptr, &cntr2, getCurrentTime())
{
        EmuDuration total(1.0 / 4e6); // 4MHz
        EmuDuration hi   (1.0 / 8e6); // 8MHz half clock period
        EmuTime::param time = getCurrentTime();
        i8254.getClockPin(0).setPeriodicState(total, hi, time);
        i8254.getClockPin(1).setState(false, time);
        i8254.getClockPin(2).setPeriodicState(total, hi, time);
        i8254.getOutputPin(2).generateEdgeSignals(true, time);
        reset(time);
 
        if (isExternalMSXMIDI) {
                // Ports are dynamically registered.
                if (config.findChild("io")) {
                        throw MSXException(
                                "Bad MSX-MIDI configuration, when using "
                                "'external', you cannot specify I/O ports!");
                }
                // Out-port 0xE2 is always enabled.
                getCPUInterface().register_IO_Out(0xE2, this);
                // Not enabled, so no other ports need to be registered yet.
                assert(!isEnabled);
        } else {
                // Ports are statically registered (via the config file).
        }
}
 
MSXMidi::~MSXMidi()
{
        if (isExternalMSXMIDI) {
                registerIOports(DISABLED_VALUE | LIMITED_RANGE_VALUE); // disabled, unregisters ports
                getCPUInterface().unregister_IO_Out(0xE2, this);
        }
}
 
void MSXMidi::reset(EmuTime::param time)
{
        timerIRQlatch = false;
        timerIRQenabled = false;
        timerIRQ.reset();
        rxrdyIRQlatch = false;
        rxrdyIRQenabled = false;
        rxrdyIRQ.reset();
 
        if (isExternalMSXMIDI) {
                registerIOports(DISABLED_VALUE | LIMITED_RANGE_VALUE); // also resets state
        }
        i8251.reset(time);
}
 
byte MSXMidi::readIO(word port, EmuTime::param time)
{
        // If not enabled then no ports should have been registered.
        assert(isEnabled);
 
        // This handles both ports in range 0xE0-0xE1 and 0xE8-0xEF
        // Depending on the value written to 0xE2 they are active or not
        switch (port & 7) {
                case 0: // UART data register
                case 1: // UART status register
                        return i8251.readIO(port & 1, time);
                case 2: // timer interrupt flag off
                case 3: // no function
                        return 0xFF;
                case 4: // counter 0 data port
                case 5: // counter 1 data port
                case 6: // counter 2 data port
                case 7: // timer command register
                        return i8254.readIO(port & 3, time);
                default:
                        UNREACHABLE;
        }
}
 
byte MSXMidi::peekIO(word port, EmuTime::param time) const
{
        // If not enabled then no ports should have been registered.
        assert(isEnabled);
 
        // This handles both ports in range 0xE0-0xE1 and 0xE8-0xEF
        // Depending on the value written to 0xE2 they are active or not
        switch (port & 7) {
                case 0: // UART data register
                case 1: // UART status register
                        return i8251.peekIO(port & 1, time);
                case 2: // timer interrupt flag off
                case 3: // no function
                        return 0xFF;
                case 4: // counter 0 data port
                case 5: // counter 1 data port
                case 6: // counter 2 data port
                case 7: // timer command register
                        return i8254.peekIO(port & 3, time);
                default:
                        UNREACHABLE;
        }
}
 
void MSXMidi::writeIO(word port, byte value, EmuTime::param time)
{
        if (isExternalMSXMIDI && ((port & 0xFF) == 0xE2)) {
                // control register
                registerIOports(value);
                return;
        }
        assert(isEnabled);
 
        // This handles both ports in range 0xE0-0xE1 and 0xE8-0xEF
        switch (port & 7) {
                case 0: // UART data register
                case 1: // UART command register
                        i8251.writeIO(port & 1, value, time);
                        break;
                case 2: // timer interrupt flag off
                        setTimerIRQ(false, time);
                        break;
                case 3: // no function
                        break;
                case 4: // counter 0 data port
                case 5: // counter 1 data port
                case 6: // counter 2 data port
                case 7: // timer command register
                        i8254.writeIO(port & 3, value, time);
                        break;
        }
}
 
void MSXMidi::registerIOports(byte value)
{
        assert(isExternalMSXMIDI);
        bool newIsEnabled = (value & DISABLED_VALUE) == 0;
        bool newIsLimited = (value & LIMITED_RANGE_VALUE) != 0;
 
        auto& cpuInterface = getCPUInterface();
        if (newIsEnabled != isEnabled) {
                // Enable/disabled status changes, possibly limited status
                // changes as well but that doesn't matter, we anyway need
                // to (un)register the full port range.
                if (newIsEnabled) {
                        // disabled -> enabled
                        if (newIsLimited) {
                                cpuInterface.register_IO_InOut_range(0xE0, 2, this);
                        } else {
                                cpuInterface.register_IO_InOut_range(0xE8, 8, this);
                        }
                } else {
                        // enabled -> disabled
                        if (isLimitedTo8251) { // note: old isLimited status
                                cpuInterface.unregister_IO_InOut_range(0xE0, 2, this);
                        } else {
                                cpuInterface.unregister_IO_InOut_range(0xE8, 8, this);
                        }
                }
 
        } else if (isEnabled && (newIsLimited != isLimitedTo8251)) {
                // Remains enabled, and only 'isLimited' status changes.
                // Need to switch between the low/high range.
                if (newIsLimited) {
                        // Switch high->low range.
                        cpuInterface.unregister_IO_InOut_range(0xE8, 8, this);
                        cpuInterface.register_IO_InOut_range  (0xE0, 2, this);
                } else {
                        // Switch low->high range.
                        cpuInterface.unregister_IO_InOut_range(0xE0, 2, this);
                        cpuInterface.register_IO_InOut_range  (0xE8, 8, this);
                }
        }
 
        isEnabled       = newIsEnabled;
        isLimitedTo8251 = newIsLimited;
}
 
void MSXMidi::setTimerIRQ(bool status, EmuTime::param time)
{
        if (timerIRQlatch != status) {
                timerIRQlatch = status;
                if (timerIRQenabled) {
                        timerIRQ.set(timerIRQlatch);
                }
                updateEdgeEvents(time);
        }
}
 
void MSXMidi::enableTimerIRQ(bool enabled, EmuTime::param time)
{
        if (timerIRQenabled != enabled) {
                timerIRQenabled = enabled;
                if (timerIRQlatch) {
                        timerIRQ.set(timerIRQenabled);
                }
                updateEdgeEvents(time);
        }
}
 
void MSXMidi::updateEdgeEvents(EmuTime::param time)
{
        bool wantEdges = timerIRQenabled && !timerIRQlatch;
        i8254.getOutputPin(2).generateEdgeSignals(wantEdges, time);
}
 
void MSXMidi::setRxRDYIRQ(bool status)
{
        if (rxrdyIRQlatch != status) {
                rxrdyIRQlatch = status;
                if (rxrdyIRQenabled) {
                        rxrdyIRQ.set(rxrdyIRQlatch);
                }
        }
}
 
void MSXMidi::enableRxRDYIRQ(bool enabled)
{
        if (rxrdyIRQenabled != enabled) {
                rxrdyIRQenabled = enabled;
                if (!rxrdyIRQenabled && rxrdyIRQlatch) {
                        rxrdyIRQ.reset();
                }
        }
}
 
 
// I8251Interface  (pass calls from I8251 to outConnector)
 
void MSXMidi::Interface::setRxRDY(bool status, EmuTime::param /*time*/)
{
        auto& midi = OUTER(MSXMidi, interface);
        midi.setRxRDYIRQ(status);
}
 
void MSXMidi::Interface::setDTR(bool status, EmuTime::param time)
{
        auto& midi = OUTER(MSXMidi, interface);
        midi.enableTimerIRQ(status, time);
}
 
void MSXMidi::Interface::setRTS(bool status, EmuTime::param /*time*/)
{
        auto& midi = OUTER(MSXMidi, interface);
        midi.enableRxRDYIRQ(status);
}
 
bool MSXMidi::Interface::getDSR(EmuTime::param /*time*/)
{
        const auto& midi = OUTER(MSXMidi, interface);
        return midi.timerIRQ.getState();
}
 
bool MSXMidi::Interface::getCTS(EmuTime::param /*time*/)
{
        return true;
}
 
void MSXMidi::Interface::setDataBits(DataBits bits)
{
        auto& midi = OUTER(MSXMidi, interface);
        midi.outConnector.setDataBits(bits);
}
 
void MSXMidi::Interface::setStopBits(StopBits bits)
{
        auto& midi = OUTER(MSXMidi, interface);
        midi.outConnector.setStopBits(bits);
}
 
void MSXMidi::Interface::setParityBit(bool enable, Parity parity)
{
        auto& midi = OUTER(MSXMidi, interface);
        midi.outConnector.setParityBit(enable, parity);
}
 
void MSXMidi::Interface::recvByte(byte value, EmuTime::param time)
{
        auto& midi = OUTER(MSXMidi, interface);
        midi.outConnector.recvByte(value, time);
}
 
void MSXMidi::Interface::signal(EmuTime::param time)
{
        const auto& midi = OUTER(MSXMidi, interface);
        midi.getPluggedMidiInDev().signal(time);
}
 
 
// Counter 0 output
 
void MSXMidi::Counter0::signal(ClockPin& pin, EmuTime::param time)
{
        auto& midi = OUTER(MSXMidi, cntr0);
        ClockPin& clk = midi.i8251.getClockPin();
        if (pin.isPeriodic()) {
                clk.setPeriodicState(pin.getTotalDuration(),
                                     pin.getHighDuration(), time);
        } else {
                clk.setState(pin.getState(time), time);
        }
}
 
void MSXMidi::Counter0::signalPosEdge(ClockPin& /*pin*/, EmuTime::param /*time*/)
{
        UNREACHABLE;
}
 
 
// Counter 2 output
 
void MSXMidi::Counter2::signal(ClockPin& pin, EmuTime::param time)
{
        auto& midi = OUTER(MSXMidi, cntr2);
        ClockPin& clk = midi.i8254.getClockPin(1);
        if (pin.isPeriodic()) {
                clk.setPeriodicState(pin.getTotalDuration(),
                                     pin.getHighDuration(), time);
        } else {
                clk.setState(pin.getState(time), time);
        }
}
 
void MSXMidi::Counter2::signalPosEdge(ClockPin& /*pin*/, EmuTime::param time)
{
        auto& midi = OUTER(MSXMidi, cntr2);
        midi.setTimerIRQ(true, time);
}
 
 
// MidiInConnector
 
bool MSXMidi::ready()
{
        return i8251.isRecvReady();
}
 
bool MSXMidi::acceptsData()
{
        return i8251.isRecvEnabled();
}
 
void MSXMidi::setDataBits(DataBits bits)
{
        i8251.setDataBits(bits);
}
 
void MSXMidi::setStopBits(StopBits bits)
{
        i8251.setStopBits(bits);
}
 
void MSXMidi::setParityBit(bool enable, Parity parity)
{
        i8251.setParityBit(enable, parity);
}
 
void MSXMidi::recvByte(byte value, EmuTime::param time)
{
        i8251.recvByte(value, time);
}
 
 
template<typename Archive>
void MSXMidi::serialize(Archive& ar, unsigned version)
{
        ar.template serializeBase<MSXDevice>(*this);
 
        ar.template serializeBase<MidiInConnector>(*this);
        ar.serialize("outConnector",    outConnector,
                     "timerIRQ",        timerIRQ,
                     "rxrdyIRQ",        rxrdyIRQ,
                     "timerIRQlatch",   timerIRQlatch,
                     "timerIRQenabled", timerIRQenabled,
                     "rxrdyIRQlatch",   rxrdyIRQlatch,
                     "rxrdyIRQenabled", rxrdyIRQenabled,
                     "I8251",           i8251,
                     "I8254",           i8254);
        if (ar.versionAtLeast(version, 2)) {
                bool newIsEnabled = isEnabled; // copy for saver
                bool newIsLimitedTo8251 = isLimitedTo8251; // copy for saver
                ar.serialize("isEnabled",       newIsEnabled,
                             "isLimitedTo8251", newIsLimitedTo8251);
                if constexpr (Archive::IS_LOADER) {
                        if (isExternalMSXMIDI) {
                                registerIOports((newIsEnabled ? 0x00 : DISABLED_VALUE) | (newIsLimitedTo8251 ? LIMITED_RANGE_VALUE : 0x00));
                        }
                }
        }
 
        // don't serialize:  cntr0, cntr2, interface
}
INSTANTIATE_SERIALIZE_METHODS(MSXMidi);
REGISTER_MSXDEVICE(MSXMidi, "MSX-Midi");
 
} // namespace openmsx