third_party/WebKit/Source/platform/audio/AudioPullFIFO.cpp

/*
 * Copyright (C) 2012 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions
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 *
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 *     notice, this list of conditions and the following disclaimer in the
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 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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#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