/*

 * 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

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * 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, size_t renderPhase)

    : m_frame(fftSize)

    , m_readWriteIndex(renderPhase % (fftSize / 2))

{

    MOZ_ASSERT(fftSize >= 2 * WEBAUDIO_BLOCK_SIZE);

  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.ShallowSizeOfExcludingThis(aMallocSizeOf);

    amount += m_outputBuffer.ShallowSizeOfExcludingThis(aMallocSizeOf);

    amount += m_lastOverlapBuffer.ShallowSizeOfExcludingThis(aMallocSizeOf);

    return amount;

}

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

{

  return aMallocSizeOf(this) + sizeOfExcludingThis(aMallocSizeOf);

}

const float* FFTConvolver::process(FFTBlock* fftKernel, const float* sourceP)

{

    size_t halfSize = fftSize() / 2;

    // WEBAUDIO_BLOCK_SIZE must be an exact multiple of halfSize,

    // halfSize must be a multiple of WEBAUDIO_BLOCK_SIZE

    // and > WEBAUDIO_BLOCK_SIZE.

    MOZ_ASSERT(halfSize % WEBAUDIO_BLOCK_SIZE == 0 &&

               WEBAUDIO_BLOCK_SIZE <= halfSize);

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

    float* inputP = m_inputBuffer.Elements();

    MOZ_ASSERT(sourceP && inputP && m_readWriteIndex + WEBAUDIO_BLOCK_SIZE <= m_inputBuffer.Length());

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

    float* outputP = m_outputBuffer.Elements();

    m_readWriteIndex += WEBAUDIO_BLOCK_SIZE;

    // 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

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

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

        // Reset index back to start for next time

        m_readWriteIndex = 0;

    }

    return outputP + m_readWriteIndex;

}

void FFTConvolver::reset()

{

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

    m_readWriteIndex = 0;

}

size_t FFTConvolver::latencyFrames() const

{

    return std::max<size_t>(fftSize()/2, WEBAUDIO_BLOCK_SIZE) -

        WEBAUDIO_BLOCK_SIZE;

}

} // namespace WebCore