Source/WebCore/platform/audio/ReverbAccumulationBuffer.cpp

/*
 * 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.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
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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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#include "config.h"

#if ENABLE(WEB_AUDIO)

#include "ReverbAccumulationBuffer.h"

#include "VectorMath.h"

#include <algorithm>

namespace WebCore {

ReverbAccumulationBuffer::ReverbAccumulationBuffer(size_t length)
    : m_buffer(length)
{
}

void ReverbAccumulationBuffer::readAndClear(float* destination, size_t numberOfFrames)
{
    size_t bufferLength = m_buffer.size();
    bool isCopySafe = m_readIndex <= bufferLength && numberOfFrames <= bufferLength;
    
    ASSERT(isCopySafe);
    if (!isCopySafe)
        return;

    size_t framesAvailable = bufferLength - m_readIndex;
    size_t numberOfFrames1 = std::min(numberOfFrames, framesAvailable);
    size_t numberOfFrames2 = numberOfFrames - numberOfFrames1;

    float* source = m_buffer.data();
    memcpy(destination, source + m_readIndex, sizeof(float) * numberOfFrames1);
    memset(source + m_readIndex, 0, sizeof(float) * numberOfFrames1);

    // Handle wrap-around if necessary
    if (numberOfFrames2 > 0) {
        memcpy(destination + numberOfFrames1, source, sizeof(float) * numberOfFrames2);
        memset(source, 0, sizeof(float) * numberOfFrames2);
    }

    m_readIndex = (m_readIndex + numberOfFrames) % bufferLength;
    m_readTimeFrame += numberOfFrames;
}

void ReverbAccumulationBuffer::updateReadIndex(int* readIndex, size_t numberOfFrames) const
{
    // Update caller's readIndex
    *readIndex = (*readIndex + numberOfFrames) % m_buffer.size();
}

int ReverbAccumulationBuffer::accumulate(float* source, size_t numberOfFrames, int* readIndex, size_t delayFrames)
{
    size_t bufferLength = m_buffer.size();
    
    size_t writeIndex = (*readIndex + delayFrames) % bufferLength;

    // Update caller's readIndex
    *readIndex = (*readIndex + numberOfFrames) % bufferLength;

    size_t framesAvailable = bufferLength - writeIndex;
    size_t numberOfFrames1 = std::min(numberOfFrames, framesAvailable);
    size_t numberOfFrames2 = numberOfFrames - numberOfFrames1;

    float* destination = m_buffer.data();

    bool isSafe = writeIndex <= bufferLength && numberOfFrames1 + writeIndex <= bufferLength && numberOfFrames2 <= bufferLength;
    ASSERT(isSafe);
    if (!isSafe)
        return 0;

    VectorMath::add(source, destination + writeIndex, destination + writeIndex, numberOfFrames1);

    // Handle wrap-around if necessary
    if (numberOfFrames2 > 0)       
        VectorMath::add(source + numberOfFrames1, destination, destination, numberOfFrames2);

    return writeIndex;
}

void ReverbAccumulationBuffer::reset()
{
    m_buffer.zero();
    m_readIndex = 0;
    m_readTimeFrame = 0;
}

} // namespace WebCore

#endif // ENABLE(WEB_AUDIO)