JUCE/modules/juce_audio_devices/midi_io/juce_MidiOutput.cpp

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

   This file is part of the JUCE library.
   Copyright (c) 2017 - ROLI Ltd.

   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.

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

struct MidiOutput::PendingMessage
{
    PendingMessage (const void* const data, const int len, const double timeStamp)
        : message (data, len, timeStamp)
    {}

    MidiMessage message;
    PendingMessage* next;
};

MidiOutput::MidiOutput (const String& midiName)
    : Thread ("midi out"),
      internal (nullptr),
      firstMessage (nullptr),
      name (midiName)
{
}

void MidiOutput::sendBlockOfMessagesNow (const MidiBuffer& buffer)
{
    MidiBuffer::Iterator i (buffer);
    MidiMessage message;
    int samplePosition; // Note: not actually used, so no need to initialise.

    while (i.getNextEvent (message, samplePosition))
        sendMessageNow (message);
}

void MidiOutput::sendBlockOfMessages (const MidiBuffer& buffer,
                                      const double millisecondCounterToStartAt,
                                      double samplesPerSecondForBuffer)
{
    // You've got to call startBackgroundThread() for this to actually work..
    jassert (isThreadRunning());

    // this needs to be a value in the future - RTFM for this method!
    jassert (millisecondCounterToStartAt > 0);

    const double timeScaleFactor = 1000.0 / samplesPerSecondForBuffer;

    MidiBuffer::Iterator i (buffer);

    const uint8* data;
    int len, time;

    while (i.getNextEvent (data, len, time))
    {
        const double eventTime = millisecondCounterToStartAt + timeScaleFactor * time;

        PendingMessage* const m = new PendingMessage (data, len, eventTime);

        const ScopedLock sl (lock);

        if (firstMessage == nullptr || firstMessage->message.getTimeStamp() > eventTime)
        {
            m->next = firstMessage;
            firstMessage = m;
        }
        else
        {
            PendingMessage* mm = firstMessage;

            while (mm->next != nullptr && mm->next->message.getTimeStamp() <= eventTime)
                mm = mm->next;

            m->next = mm->next;
            mm->next = m;
        }
    }

    notify();
}

void MidiOutput::clearAllPendingMessages()
{
    const ScopedLock sl (lock);

    while (firstMessage != nullptr)
    {
        PendingMessage* const m = firstMessage;
        firstMessage = firstMessage->next;
        delete m;
    }
}

void MidiOutput::startBackgroundThread()
{
    startThread (9);
}

void MidiOutput::stopBackgroundThread()
{
    stopThread (5000);
}

void MidiOutput::run()
{
    while (! threadShouldExit())
    {
        uint32 now = Time::getMillisecondCounter();
        uint32 eventTime = 0;
        uint32 timeToWait = 500;

        PendingMessage* message;

        {
            const ScopedLock sl (lock);
            message = firstMessage;

            if (message != nullptr)
            {
                eventTime = (uint32) roundToInt (message->message.getTimeStamp());

                if (eventTime > now + 20)
                {
                    timeToWait = eventTime - (now + 20);
                    message = nullptr;
                }
                else
                {
                    firstMessage = message->next;
                }
            }
        }

        if (message != nullptr)
        {
            const ScopedPointer<PendingMessage> messageDeleter (message);

            if (eventTime > now)
            {
                Time::waitForMillisecondCounter (eventTime);

                if (threadShouldExit())
                    break;
            }

            if (eventTime > now - 200)
                sendMessageNow (message->message);
        }
        else
        {
            jassert (timeToWait < 1000 * 30);
            wait ((int) timeToWait);
        }
    }

    clearAllPendingMessages();
}