MidiSessionALSA.cc

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#include "MidiSessionALSA.hh"
#include "CliComm.hh"
#include "MidiOutDevice.hh"
#include "PlugException.hh"
#include "PluggingController.hh"
#include "serialize.hh"

#include <iostream>
#include <memory>


namespace openmsx {

// MidiOutALSA ==============================================================

class MidiOutALSA final : public MidiOutDevice {
public:
        MidiOutALSA(
                        snd_seq_t& seq,
                        snd_seq_client_info_t& cinfo, snd_seq_port_info_t& pinfo);
        ~MidiOutALSA() override;

        // Pluggable
        void plugHelper(Connector& connector, EmuTime::param time) override;
        void unplugHelper(EmuTime::param time) override;
        const std::string& getName() const override;
        string_view getDescription() const override;

        // MidiOutDevice
        void recvMessage(
                        const std::vector<uint8_t>& message, EmuTime::param time) override;

        template<typename Archive>
        void serialize(Archive& ar, unsigned version);

private:
        void connect();
        void disconnect();

        snd_seq_t& seq;
        snd_midi_event_t* event_parser;
        int sourcePort;
        int destClient;
        int destPort;
        std::string name;
        std::string desc;
        bool connected;
};

MidiOutALSA::MidiOutALSA(
                snd_seq_t& seq_,
                snd_seq_client_info_t& cinfo, snd_seq_port_info_t& pinfo)
        : seq(seq_)
        , sourcePort(-1)
        , destClient(snd_seq_port_info_get_client(&pinfo))
        , destPort(snd_seq_port_info_get_port(&pinfo))
        , name(snd_seq_client_info_get_name(&cinfo))
        , desc(snd_seq_port_info_get_name(&pinfo))
        , connected(false)
{
}

MidiOutALSA::~MidiOutALSA() {
        if (connected) {
                disconnect();
        }
}

void MidiOutALSA::plugHelper(Connector& /*connector_*/, EmuTime::param /*time*/)
{
        connect();
}

void MidiOutALSA::unplugHelper(EmuTime::param /*time*/)
{
        disconnect();
}

void MidiOutALSA::connect()
{
        sourcePort = snd_seq_create_simple_port(
                &seq, "MIDI out pluggable",
                0, SND_SEQ_PORT_TYPE_MIDI_GENERIC);
        if (sourcePort < 0) {
                throw PlugException(
                        "Failed to create ALSA port: ", snd_strerror(sourcePort));
        }

        int err = snd_seq_connect_to(&seq, sourcePort, destClient, destPort);
        if (err) {
                snd_seq_delete_simple_port(&seq, sourcePort);
                throw PlugException(
                        "Failed to connect to ALSA port "
                        "(", destClient, ':', destPort, ")"
                        ": ", snd_strerror(err));
        }

        snd_midi_event_new(MAX_MESSAGE_SIZE, &event_parser);

        connected = true;
}

void MidiOutALSA::disconnect()
{
        snd_midi_event_free(event_parser);
        snd_seq_disconnect_to(&seq, sourcePort, destClient, destPort);
        snd_seq_delete_simple_port(&seq, sourcePort);

        connected = false;
}

const std::string& MidiOutALSA::getName() const
{
        return name;
}

string_view MidiOutALSA::getDescription() const
{
        return desc;
}

void MidiOutALSA::recvMessage(
                const std::vector<uint8_t>& message, EmuTime::param /*time*/)
{
        snd_seq_event_t ev;
        snd_seq_ev_clear(&ev);

        // Set routing.
        snd_seq_ev_set_source(&ev, sourcePort);
        snd_seq_ev_set_subs(&ev);

        // Set message.
        long encodeLen = snd_midi_event_encode(
                        event_parser, message.data(), message.size(), &ev);
        if (encodeLen < 0) {
                std::cerr << "Error encoding MIDI message of type "
                          << std::hex << int(message[0]) << std::dec
                          << ": " << snd_strerror(encodeLen) << '\n';
                return;
        }
        if (ev.type == SND_SEQ_EVENT_NONE) {
                std::cerr << "Incomplete MIDI message of type "
                          << std::hex << int(message[0]) << std::dec << '\n';
                return;
        }

        // Send event.
        snd_seq_ev_set_direct(&ev);
        int err = snd_seq_event_output(&seq, &ev);
        if (err < 0) {
                std::cerr << "Error sending MIDI event: "
                          << snd_strerror(err) << '\n';
        }
        snd_seq_drain_output(&seq);
}

template<typename Archive>
void MidiOutALSA::serialize(Archive& ar, unsigned /*version*/)
{
        if (ar.isLoader()) {
                connect();
        }
}
INSTANTIATE_SERIALIZE_METHODS(MidiOutALSA);
REGISTER_POLYMORPHIC_INITIALIZER(Pluggable, MidiOutALSA, "MidiOutALSA");


// MidiSessionALSA ==========================================================

std::unique_ptr<MidiSessionALSA> MidiSessionALSA::instance;

void MidiSessionALSA::registerAll(
                PluggingController& controller, CliComm& cliComm)
{
        if (!instance) {
                // Open the sequencer.
                snd_seq_t* seq;
                int err = snd_seq_open(&seq, "default", SND_SEQ_OPEN_DUPLEX, 0);
                if (err < 0) {
                        cliComm.printError(
                                "Could not open sequencer: ", snd_strerror(err));
                        return;
                }
                snd_seq_set_client_name(seq, "openMSX");
                instance.reset(new MidiSessionALSA(*seq));
        }
        instance->scanClients(controller);
}

MidiSessionALSA::MidiSessionALSA(snd_seq_t& seq_)
        : seq(seq_)
{
}

MidiSessionALSA::~MidiSessionALSA()
{
        // While the Pluggables still have a copy of this pointer, they won't
        // be accessing it anymore when openMSX is exiting.
        snd_seq_close(&seq);
}

void MidiSessionALSA::scanClients(PluggingController& controller)
{
        // Iterate through all clients.
        snd_seq_client_info_t* cinfo;
        snd_seq_client_info_alloca(&cinfo);
        snd_seq_client_info_set_client(cinfo, -1);
        while (snd_seq_query_next_client(&seq, cinfo) >= 0) {
                int client = snd_seq_client_info_get_client(cinfo);
                if (client == SND_SEQ_CLIENT_SYSTEM) {
                        continue;
                }

                // TODO: When there is more than one usable port per client,
                //       register them as separate pluggables.
                snd_seq_port_info_t* pinfo;
                snd_seq_port_info_alloca(&pinfo);
                snd_seq_port_info_set_client(pinfo, client);
                snd_seq_port_info_set_port(pinfo, -1);
                while (snd_seq_query_next_port(&seq, pinfo) >= 0) {
                        unsigned int type = snd_seq_port_info_get_type(pinfo);
                        if (!(type & SND_SEQ_PORT_TYPE_MIDI_GENERIC)) {
                                continue;
                        }
                        constexpr unsigned int wrcaps =
                                        SND_SEQ_PORT_CAP_WRITE | SND_SEQ_PORT_CAP_SUBS_WRITE;
                        if ((snd_seq_port_info_get_capability(pinfo) & wrcaps) == wrcaps) {
                                controller.registerPluggable(std::make_unique<MidiOutALSA>(
                                                seq, *cinfo, *pinfo
                                                ));
                        }
                }
        }
}

} // namespace openmsx