/*
 * Copyright (C) 2010 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
 *     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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#ifndef ReverbConvolverStage_h
#define ReverbConvolverStage_h

#include "AudioArray.h"
#include "FFTFrame.h"
#include <wtf/OwnPtr.h>

namespace WebCore {

class ReverbAccumulationBuffer;
class ReverbConvolver;
class FFTConvolver;
    
// A ReverbConvolverStage represents the convolution associated with a sub-section of a large impulse response.
// It incorporates a delay line to account for the offset of the sub-section within the larger impulse response.
class ReverbConvolverStage {
public:
    // renderPhase is useful to know so that we can manipulate the pre versus post delay so that stages will perform
    // their heavy work (FFT processing) on different slices to balance the load in a real-time thread.
    ReverbConvolverStage(float* impulseResponse, size_t responseLength, size_t reverbTotalLatency, size_t stageOffset, size_t stageLength,
                         size_t fftSize, size_t renderPhase, size_t renderSliceSize, ReverbAccumulationBuffer* accumulationBuffer);

    // WARNING: framesToProcess must be such that it evenly divides the delay buffer size (stage_offset).
    void process(float* source, size_t framesToProcess);

    void processInBackground(ReverbConvolver* convolver, size_t framesToProcess);

    void reset();

    // Useful for background processing
    int inputReadIndex() const { return m_inputReadIndex; }

private:
    FFTFrame m_fftKernel;
    OwnPtr<FFTConvolver> m_convolver;

    AudioFloatArray m_preDelayBuffer;

    ReverbAccumulationBuffer* m_accumulationBuffer;
    int m_accumulationReadIndex;
    int m_inputReadIndex;

    size_t m_preDelayLength;
    size_t m_postDelayLength;
    size_t m_preReadWriteIndex;
    size_t m_framesProcessed;

    AudioFloatArray m_temporaryBuffer;

    size_t m_impulseResponseLength;
};

} // namespace WebCore

#endif // ReverbConvolverStage_h