83 lines
3.2 KiB
C++
83 lines
3.2 KiB
C++
/*
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* Copyright 2017 The Chromium Authors. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include <wtf/Forward.h>
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#include <wtf/Noncopyable.h>
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#include <wtf/RefPtr.h>
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namespace WebCore {
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class AudioBus;
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// PushPullFIFO class is an intermediate audio sample storage between
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// WebKit-WebAudio and the renderer. The renderer's hardware callback buffer size
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// varies on the platform, but the WebAudio always renders 128 frames (render
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// quantum, RQ) thus FIFO is needed to handle the general case.
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class PushPullFIFO {
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WTF_MAKE_FAST_ALLOCATED;
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WTF_MAKE_NONCOPYABLE(PushPullFIFO);
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public:
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// Maximum FIFO length. (512 render quanta)
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static constexpr size_t maxFIFOLength { 65536 };
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// |fifoLength| cannot exceed |maxFIFOLength|. Otherwise it crashes.
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WEBCORE_EXPORT PushPullFIFO(unsigned numberOfChannels, size_t fifoLength);
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WEBCORE_EXPORT ~PushPullFIFO();
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// Pushes the rendered frames by WebAudio engine.
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// - The |inputBus| length is 128 frames (1 render quantum), fixed.
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// - In case of overflow (FIFO full while push), the existing frames in FIFO
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// will be overwritten and |indexRead| will be forcibly moved to
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// |indexWrite| to avoid reading overwritten frames.
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WEBCORE_EXPORT void push(const AudioBus* inputBus);
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// Pulls |framesRequested| by the audio device thread and returns the actual
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// number of frames to be rendered by the source. (i.e. WebAudio graph)
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WEBCORE_EXPORT size_t pull(AudioBus* outputBus, size_t framesRequested);
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size_t framesAvailable() const { return m_framesAvailable; }
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size_t length() const { return m_fifoLength; }
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unsigned numberOfChannels() const;
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AudioBus* bus() const { return m_fifoBus.get(); }
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private:
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// The size of the FIFO.
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const size_t m_fifoLength = 0;
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RefPtr<AudioBus> m_fifoBus;
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// The number of frames in the FIFO actually available for pulling.
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size_t m_framesAvailable { 0 };
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size_t m_indexRead { 0 };
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size_t m_indexWrite { 0 };
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};
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} // namespace WebCore
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