MidiOutDevice.cc

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#include "MidiOutDevice.hh"
#include "unreachable.hh"
 
 
namespace openmsx {
 
static constexpr uint8_t MIDI_MSG_SYSEX     = 0xF0;
static constexpr uint8_t MIDI_MSG_SYSEX_END = 0xF7;
static constexpr uint8_t MIDI_MSG_RESET     = 0xFF;
 
[[nodiscard]] static constexpr size_t midiMessageLength(uint8_t status)
{
        if (status < 0x80) {
                assert(false);
                return 0;
        } else if (status < 0xC0) {
                return 3;
        } else if (status < 0xE0) {
                return 2;
        } else if (status < 0xF0) {
                return 3;
        } else {
                switch (status) {
                case MIDI_MSG_SYSEX:
                        // Limit to force sending large SysEx messages in chunks.
                        return MidiOutDevice::MAX_MESSAGE_SIZE;
                case MIDI_MSG_SYSEX_END:
                        assert(false);
                        return 0;
                case 0xF1:
                case 0xF3:
                        return 2;
                case 0xF2:
                        return 3;
                case 0xF4:
                case 0xF5:
                case 0xF9:
                case 0xFD:
                        // Data size unknown
                        return 1;
                default:
                        return 1;
                }
        }
}
 
std::string_view MidiOutDevice::getClass() const
{
        return "midi out";
}
 
void MidiOutDevice::clearBuffer()
{
        buffer.clear();
        isSysEx = false;
}
 
void MidiOutDevice::recvByte(byte value, EmuTime::param time)
{
        if (value & 0x80) { // status byte
                if (value == MIDI_MSG_SYSEX_END) {
                        if (isSysEx) {
                                buffer.push_back(value);
                                recvMessage(buffer, time);
                        } else {
                                // Ignoring SysEx end without start
                        }
                        buffer.clear();
                        isSysEx = false;
                } else if (value >= 0xF8) {
                        // Realtime message, send immediately.
                        std::vector<uint8_t> realtimeMessage = { value };
                        recvMessage(realtimeMessage, time);
                        if (value == MIDI_MSG_RESET) {
                                buffer.clear();
                        }
                        return;
                } else {
                        // Replace any message in progress.
                        if (isSysEx) {
                                // Discarding incomplete MIDI SysEx message
                        } else if (buffer.size() >= 2) {
                                #if 0
                                std::cerr << "Discarding incomplete MIDI message with status "
                                             "0x" << std::hex << int(buffer[0]) << std::dec <<
                                             ", at " << buffer.size() << " of " <<
                                             midiMessageLength(buffer[0]) << " bytes\n";
                                #endif
                        }
                        buffer = { value };
                        isSysEx = value == MIDI_MSG_SYSEX;
                }
        } else { // data byte
                if (buffer.empty() && !isSysEx) {
                        // Ignoring MIDI data without preceding status
                } else {
                        buffer.push_back(value);
                }
        }
 
        // Is the message complete?
        if (!buffer.empty()) {
                uint8_t status = isSysEx ? MIDI_MSG_SYSEX : buffer[0];
                size_t len = midiMessageLength(status);
                if (buffer.size() >= len) {
                        recvMessage(buffer, time);
                        if (status >= 0xF0 && status < 0xF8) {
                                buffer.clear();
                        } else {
                                // Keep last status, to support running status.
                                buffer.resize(1);
                        }
                }
        }
}
 
void MidiOutDevice::recvMessage(
                const std::vector<uint8_t>& /*message*/, EmuTime::param /*time*/)
{
        UNREACHABLE;
}
 
void MidiOutDevice::setDataBits(DataBits /*bits*/)
{
        // ignore
}
 
void MidiOutDevice::setStopBits(StopBits /*bits*/)
{
        // ignore
}
 
void MidiOutDevice::setParityBit(bool /*enable*/, ParityBit /*parity*/)
{
        // ignore
}
 
} // namespace openmsx