Source/platform/audio/AudioPullFIFO.cpp

/*
 * Copyright (C) 2012 Google Inc. All rights reserved.
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 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
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 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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#include "config.h"

#if ENABLE(WEB_AUDIO)

#include "platform/audio/AudioPullFIFO.h"

namespace blink {

AudioPullFIFO::AudioPullFIFO(AudioSourceProvider& audioProvider, unsigned numberOfChannels, size_t fifoLength, size_t providerSize)
    : m_provider(audioProvider)
    , m_fifo(numberOfChannels, fifoLength)
    , m_providerSize(providerSize)
    , m_tempBus(AudioBus::create(numberOfChannels, providerSize))
{
}

void AudioPullFIFO::consume(AudioBus* destination, size_t framesToConsume)
{
    if (!destination)
        return;

    if (framesToConsume > m_fifo.framesInFifo()) {
        // We don't have enough data in the FIFO to fulfill the request. Ask for more data.
        fillBuffer(framesToConsume - m_fifo.framesInFifo());
    }

    m_fifo.consume(destination, framesToConsume);
}

void AudioPullFIFO::fillBuffer(size_t numberOfFrames)
{
    // Keep asking the provider to give us data until we have received at least |numberOfFrames| of
    // data. Stuff the data into the FIFO.
    size_t framesProvided = 0;

    while (framesProvided < numberOfFrames) {
        m_provider.provideInput(m_tempBus.get(), m_providerSize);

        m_fifo.push(m_tempBus.get());

        framesProvided += m_providerSize;
    }
}

} // namespace blink

#endif // ENABLE(WEB_AUDIO)