/*
 * 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.
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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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#ifndef FFTConvolver_h
#define FFTConvolver_h

#include "nsTArray.h"
#include "mozilla/FFTBlock.h"
#include "mozilla/MemoryReporting.h"

namespace WebCore {

typedef AlignedTArray<float> AlignedAudioFloatArray;
using mozilla::FFTBlock;

class FFTConvolver {
 public:
  // |fftSize| must be a power of two.
  //
  // |renderPhase| is the initial offset in the initially zero input buffer.
  // It is coordinated with the other stages, so they don't all do their
  // FFTs at the same time.
  explicit FFTConvolver(size_t fftSize, size_t renderPhase = 0);

  // Process WEBAUDIO_BLOCK_SIZE elements of array |sourceP| and return a
  // pointer to an output array of the same size.
  //
  // |fftKernel| must be pre-scaled for FFTBlock::GetInverseWithoutScaling().
  //
  // FIXME: Later, we can do more sophisticated buffering to relax this
  // requirement...
  const float* process(FFTBlock* fftKernel, const float* sourceP);

  void reset();

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

  // The input to output latency is up to fftSize / 2, but alignment of the
  // FFTs with the blocks reduces this by one block.
  size_t latencyFrames() const;

  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;
  AlignedAudioFloatArray m_inputBuffer;

  // Stores output which we read a little at a time
  AlignedAudioFloatArray 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
  AlignedAudioFloatArray m_lastOverlapBuffer;
};

}  // namespace WebCore

#endif  // FFTConvolver_h