/*
 * 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;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef FFTConvolver_h
#define FFTConvolver_h

#include "platform/audio/AudioArray.h"
#include "platform/audio/FFTFrame.h"
#include "wtf/Allocator.h"
#include "wtf/Noncopyable.h"

namespace blink {

class PLATFORM_EXPORT FFTConvolver {
  USING_FAST_MALLOC(FFTConvolver);
  WTF_MAKE_NONCOPYABLE(FFTConvolver);

 public:
  // fftSize must be a power of two
  FFTConvolver(size_t fftSize);

  // 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(FFTFrame* fftKernel,
               const float* sourceP,
               float* destP,
               size_t framesToProcess);

  void reset();

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

 private:
  FFTFrame 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 blink

#endif  // FFTConvolver_h
