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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;

  * 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.

  */

 #include "FFTConvolver.h"

 #include "mozilla/PodOperations.h"

 using namespace mozilla;

 namespace WebCore {

 FFTConvolver::FFTConvolver(size_t fftSize)

     : m_frame(fftSize)

     , m_readWriteIndex(0)

 {

   m_inputBuffer.SetLength(fftSize);

   PodZero(m_inputBuffer.Elements(), fftSize);

   m_outputBuffer.SetLength(fftSize);

   PodZero(m_outputBuffer.Elements(), fftSize);

   m_lastOverlapBuffer.SetLength(fftSize / 2);

   PodZero(m_lastOverlapBuffer.Elements(), fftSize / 2);

 }

 size_t FFTConvolver::sizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const

 {

     size_t amount = 0;

     amount += m_frame.SizeOfExcludingThis(aMallocSizeOf);

     amount += m_inputBuffer.SizeOfExcludingThis(aMallocSizeOf);

     amount += m_outputBuffer.SizeOfExcludingThis(aMallocSizeOf);

     amount += m_lastOverlapBuffer.SizeOfExcludingThis(aMallocSizeOf);

     return amount;

 }

 size_t FFTConvolver::sizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const

 {

   return aMallocSizeOf(this) + sizeOfExcludingThis(aMallocSizeOf);

 }

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

 {

     size_t halfSize = fftSize() / 2;

     // framesToProcess must be an exact multiple of halfSize,

     // or halfSize is a multiple of framesToProcess when halfSize > framesToProcess.

     bool isGood = !(halfSize % framesToProcess && framesToProcess % halfSize);

     MOZ_ASSERT(isGood);

     if (!isGood)

         return;

     size_t numberOfDivisions = halfSize <= framesToProcess ? (framesToProcess / halfSize) : 1;

     size_t divisionSize = numberOfDivisions == 1 ? framesToProcess : halfSize;

     for (size_t i = 0; i < numberOfDivisions; ++i, sourceP += divisionSize, destP += divisionSize) {

         // Copy samples to input buffer (note contraint above!)

         float* inputP = m_inputBuffer.Elements();

         // Sanity check

         bool isCopyGood1 = sourceP && inputP && m_readWriteIndex + divisionSize <= m_inputBuffer.Length();

         MOZ_ASSERT(isCopyGood1);

         if (!isCopyGood1)

             return;

         memcpy(inputP + m_readWriteIndex, sourceP, sizeof(float) * divisionSize);

         // Copy samples from output buffer

         float* outputP = m_outputBuffer.Elements();

         // Sanity check

         bool isCopyGood2 = destP && outputP && m_readWriteIndex + divisionSize <= m_outputBuffer.Length();

         MOZ_ASSERT(isCopyGood2);

         if (!isCopyGood2)

             return;

         memcpy(destP, outputP + m_readWriteIndex, sizeof(float) * divisionSize);

         m_readWriteIndex += divisionSize;

         // Check if it's time to perform the next FFT

         if (m_readWriteIndex == halfSize) {

             // The input buffer is now filled (get frequency-domain version)

             m_frame.PerformFFT(m_inputBuffer.Elements());

             m_frame.Multiply(*fftKernel);

             m_frame.GetInverseWithoutScaling(m_outputBuffer.Elements());

             // Overlap-add 1st half from previous time

             AudioBufferAddWithScale(m_lastOverlapBuffer.Elements(), 1.0f,

                                     m_outputBuffer.Elements(), halfSize);

             // Finally, save 2nd half of result

             bool isCopyGood3 = m_outputBuffer.Length() == 2 * halfSize && m_lastOverlapBuffer.Length() == halfSize;

             MOZ_ASSERT(isCopyGood3);

             if (!isCopyGood3)

                 return;

             memcpy(m_lastOverlapBuffer.Elements(), m_outputBuffer.Elements() + halfSize, sizeof(float) * halfSize);

             // Reset index back to start for next time

             m_readWriteIndex = 0;

         }

     }

 }

 void FFTConvolver::reset()

 {

     PodZero(m_lastOverlapBuffer.Elements(), m_lastOverlapBuffer.Length());

     m_readWriteIndex = 0;

 }

 } // namespace WebCore