JUCE/modules/juce_audio_basics/midi/juce_MidiDataConcatenator.h

/*
  ==============================================================================

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  ==============================================================================
*/

namespace juce
{

//==============================================================================
/**
    Helper class that takes chunks of incoming midi bytes, packages them into
    messages, and dispatches them to a midi callback.

    @tags{Audio}
*/
class MidiDataConcatenator
{
public:
    MidiDataConcatenator (int initialBufferSize)
        : pendingSysexData ((size_t) initialBufferSize)
    {
    }

    void reset()
    {
        currentMessageLen = 0;
        pendingSysexSize = 0;
        pendingSysexTime = 0;
    }

    template <typename UserDataType, typename CallbackType>
    void pushMidiData (const void* inputData, int numBytes, double time,
                       UserDataType* input, CallbackType& callback)
    {
        auto d = static_cast<const uint8*> (inputData);

        while (numBytes > 0)
        {
            auto nextByte = *d;

            if (pendingSysexSize != 0 || nextByte == 0xf0)
            {
                processSysex (d, numBytes, time, input, callback);
                currentMessageLen = 0;
                continue;
            }

            ++d;
            --numBytes;

            if (isRealtimeMessage (nextByte))
            {
                callback.handleIncomingMidiMessage (input, MidiMessage (nextByte, time));
                // These can be embedded in the middle of a normal message, so we won't
                // reset the currentMessageLen here.
                continue;
            }

            if (isInitialByte (nextByte))
            {
                currentMessage[0] = nextByte;
                currentMessageLen = 1;
            }
            else if (currentMessageLen > 0 && currentMessageLen < 3)
            {
                currentMessage[currentMessageLen++] = nextByte;
            }
            else
            {
                // message is too long or invalid MIDI - abandon it and start again with the next byte
                currentMessageLen = 0;
                continue;
            }

            auto expectedLength = MidiMessage::getMessageLengthFromFirstByte (currentMessage[0]);

            if (expectedLength == currentMessageLen)
            {
                callback.handleIncomingMidiMessage (input, MidiMessage (currentMessage, expectedLength, time));
                currentMessageLen = 1; // reset, but leave the first byte to use as the running status byte
            }
        }
    }

private:
    template <typename UserDataType, typename CallbackType>
    void processSysex (const uint8*& d, int& numBytes, double time,
                       UserDataType* input, CallbackType& callback)
    {
        if (*d == 0xf0)
        {
            pendingSysexSize = 0;
            pendingSysexTime = time;
        }

        pendingSysexData.ensureSize ((size_t) (pendingSysexSize + numBytes), false);
        auto totalMessage = static_cast<uint8*> (pendingSysexData.getData());
        auto dest = totalMessage + pendingSysexSize;

        do
        {
            if (pendingSysexSize > 0 && isStatusByte (*d))
            {
                if (*d == 0xf7)
                {
                    *dest++ = *d++;
                    ++pendingSysexSize;
                    --numBytes;
                    break;
                }

                if (*d >= 0xfa || *d == 0xf8)
                {
                    callback.handleIncomingMidiMessage (input, MidiMessage (*d, time));
                    ++d;
                    --numBytes;
                }
                else
                {
                    pendingSysexSize = 0;
                    int used = 0;
                    const MidiMessage m (d, numBytes, used, 0, time);

                    if (used > 0)
                    {
                        callback.handleIncomingMidiMessage (input, m);
                        numBytes -= used;
                        d += used;
                    }

                    break;
                }
            }
            else
            {
                *dest++ = *d++;
                ++pendingSysexSize;
                --numBytes;
            }
        }
        while (numBytes > 0);

        if (pendingSysexSize > 0)
        {
            if (totalMessage [pendingSysexSize - 1] == 0xf7)
            {
                callback.handleIncomingMidiMessage (input, MidiMessage (totalMessage, pendingSysexSize, pendingSysexTime));
                pendingSysexSize = 0;
            }
            else
            {
                callback.handlePartialSysexMessage (input, totalMessage, pendingSysexSize, pendingSysexTime);
            }
        }
    }

    static bool isRealtimeMessage (uint8 byte)  { return byte >= 0xf8 && byte <= 0xfe; }
    static bool isStatusByte (uint8 byte)       { return byte >= 0x80; }
    static bool isInitialByte (uint8 byte)      { return isStatusByte (byte) && byte != 0xf7; }

    uint8 currentMessage[3];
    int currentMessageLen = 0;

    MemoryBlock pendingSysexData;
    double pendingSysexTime = 0;
    int pendingSysexSize = 0;

    JUCE_DECLARE_NON_COPYABLE (MidiDataConcatenator)
};

} // namespace juce