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 /*

  * Copyright (C) 2010 Google Inc. All rights reserved.

  *

  * Redistribution and use in source and binary forms, with or without

  * 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

  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY

  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

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  */

 #ifndef FFTConvolver_h

 #define FFTConvolver_h

 #include "nsTArray.h"

 #include "mozilla/FFTBlock.h"

 #include "mozilla/MemoryReporting.h"

 namespace WebCore {

 typedef nsTArray<float> AudioFloatArray;

 using mozilla::FFTBlock;

 class FFTConvolver {

 public:

     // fftSize must be a power of two

     FFTConvolver(size_t fftSize);

     // |fftKernel| must be pre-scaled for FFTBlock::GetInverseWithoutScaling().

     //

     // For now, with multiple calls to Process(), framesToProcess MUST add up EXACTLY to fftSize / 2

     //

     // FIXME: Later, we can do more sophisticated buffering to relax this requirement...

     //

     // The input to output latency is equal to fftSize / 2

     //

     // Processing in-place is allowed...

     void process(FFTBlock* fftKernel, const float* sourceP, float* destP, size_t framesToProcess);

     void reset();

     size_t fftSize() const { return m_frame.FFTSize(); }

     size_t sizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;

     size_t sizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;

 private:

     FFTBlock m_frame;

     // Buffer input until we get fftSize / 2 samples then do an FFT

     size_t m_readWriteIndex;

     AudioFloatArray m_inputBuffer;

     // Stores output which we read a little at a time

     AudioFloatArray m_outputBuffer;

     // Saves the 2nd half of the FFT buffer, so we can do an overlap-add with the 1st half of the next one

     AudioFloatArray m_lastOverlapBuffer;

 };

 } // namespace WebCore

 #endif // FFTConvolver_h