JUCE/modules/juce_audio_basics/midi/juce_MidiDataConcatenator.h

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

   This file is part of the JUCE library.
   Copyright (c) 2022 - Raw Material Software Limited

   JUCE is an open source library subject to commercial or open-source
   licensing.

   The code included in this file is provided under the terms of the ISC license
   http://www.isc.org/downloads/software-support-policy/isc-license. Permission
   To use, copy, modify, and/or distribute this software for any purpose with or
   without fee is hereby granted provided that the above copyright notice and
   this permission notice appear in all copies.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

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

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