root/Source/platform/audio/ReverbAccumulationBuffer.cpp

DEFINITIONS

1. m_readTimeFrame
2. readAndClear
3. updateReadIndex
4. accumulate
5. reset

/*
 * 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;
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#include "config.h"

#if ENABLE(WEB_AUDIO)

#include "platform/audio/ReverbAccumulationBuffer.h"

#include "platform/audio/VectorMath.h"

namespace WebCore {

using namespace VectorMath;

ReverbAccumulationBuffer::ReverbAccumulationBuffer(size_t length)
    : m_buffer(length)
    , m_readIndex(0)
    , m_readTimeFrame(0)
{
}

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;

    vadd(source, 1, destination + writeIndex, 1, destination + writeIndex, 1, numberOfFrames1);

    // Handle wrap-around if necessary
    if (numberOfFrames2 > 0)
        vadd(source + numberOfFrames1, 1, destination, 1, destination, 1, numberOfFrames2);

    return writeIndex;
}

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

} // namespace WebCore

#endif // ENABLE(WEB_AUDIO)