Source/WebCore/platform/audio/ReverbInputBuffer.cpp

/*
 * 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:
 *
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 *     notice, this list of conditions and the following disclaimer.
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 *     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
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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#include "config.h"

#if ENABLE(WEB_AUDIO)

#include "ReverbInputBuffer.h"

namespace WebCore {

ReverbInputBuffer::ReverbInputBuffer(size_t length)
    : m_buffer(length)
    , m_writeIndex(0)
{
}

void ReverbInputBuffer::write(const float* sourceP, size_t numberOfFrames)
{
    size_t bufferLength = m_buffer.size();
    bool isCopySafe = m_writeIndex + numberOfFrames <= bufferLength;
    ASSERT(isCopySafe);
    if (!isCopySafe)
        return;
        
    memcpy(m_buffer.data() + m_writeIndex, sourceP, sizeof(float) * numberOfFrames);

    m_writeIndex += numberOfFrames;
    ASSERT(m_writeIndex <= bufferLength);

    if (m_writeIndex >= bufferLength)
        m_writeIndex = 0;
}

float* ReverbInputBuffer::directReadFrom(int* readIndex, size_t numberOfFrames)
{
    size_t bufferLength = m_buffer.size();
    bool isPointerGood = readIndex && *readIndex >= 0 && *readIndex + numberOfFrames <= bufferLength;
    ASSERT(isPointerGood);
    if (!isPointerGood) {
        // Should never happen in practice but return pointer to start of buffer (avoid crash)
        if (readIndex)
            *readIndex = 0;
        return m_buffer.data();
    }
        
    float* sourceP = m_buffer.data();
    float* p = sourceP + *readIndex;

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

    return p;
}

void ReverbInputBuffer::reset()
{
    m_buffer.zero();
    m_writeIndex = 0;
}

} // namespace WebCore

#endif // ENABLE(WEB_AUDIO)