The Tor Browser: content/media/webaudio/blink/ReverbAccumulationBuffer.cpp@44a2da4a2ab2

Replace accessor implementation with direct member state manipulation, by
request https://trac.torproject.org/projects/tor/ticket/9701#comment:32

     1 /*

     2  * Copyright (C) 2010 Google Inc. All rights reserved.

     3  *

     4  * Redistribution and use in source and binary forms, with or without

     5  * modification, are permitted provided that the following conditions

     6  * are met:

     7  *

     8  * 1.  Redistributions of source code must retain the above copyright

     9  *     notice, this list of conditions and the following disclaimer.

    10  * 2.  Redistributions in binary form must reproduce the above copyright

    11  *     notice, this list of conditions and the following disclaimer in the

    12  *     documentation and/or other materials provided with the distribution.

    13  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of

    14  *     its contributors may be used to endorse or promote products derived

    15  *     from this software without specific prior written permission.

    16  *

    17  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY

    18  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

    19  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

    20  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY

    21  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

    22  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

    23  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND

    24  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

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

    26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

    27  */

    29 #include "ReverbAccumulationBuffer.h"

    30 #include "AudioNodeEngine.h"

    31 #include "mozilla/PodOperations.h"

    32 #include <algorithm>

    34 using namespace mozilla;

    36 namespace WebCore {

    38 ReverbAccumulationBuffer::ReverbAccumulationBuffer(size_t length)

    39     : m_readIndex(0)

    40     , m_readTimeFrame(0)

    41 {

    42   m_buffer.SetLength(length);

    43   PodZero(m_buffer.Elements(), length);

    44 }

    46 void ReverbAccumulationBuffer::readAndClear(float* destination, size_t numberOfFrames)

    47 {

    48     size_t bufferLength = m_buffer.Length();

    49     bool isCopySafe = m_readIndex <= bufferLength && numberOfFrames <= bufferLength;

    51     MOZ_ASSERT(isCopySafe);

    52     if (!isCopySafe)

    53         return;

    55     size_t framesAvailable = bufferLength - m_readIndex;

    56     size_t numberOfFrames1 = std::min(numberOfFrames, framesAvailable);

    57     size_t numberOfFrames2 = numberOfFrames - numberOfFrames1;

    59     float* source = m_buffer.Elements();

    60     memcpy(destination, source + m_readIndex, sizeof(float) * numberOfFrames1);

    61     memset(source + m_readIndex, 0, sizeof(float) * numberOfFrames1);

    63     // Handle wrap-around if necessary

    64     if (numberOfFrames2 > 0) {

    65         memcpy(destination + numberOfFrames1, source, sizeof(float) * numberOfFrames2);

    66         memset(source, 0, sizeof(float) * numberOfFrames2);

    67     }

    69     m_readIndex = (m_readIndex + numberOfFrames) % bufferLength;

    70     m_readTimeFrame += numberOfFrames;

    71 }

    73 void ReverbAccumulationBuffer::updateReadIndex(int* readIndex, size_t numberOfFrames) const

    74 {

    75     // Update caller's readIndex

    76     *readIndex = (*readIndex + numberOfFrames) % m_buffer.Length();

    77 }

    79 int ReverbAccumulationBuffer::accumulate(float* source, size_t numberOfFrames, int* readIndex, size_t delayFrames)

    80 {

    81     size_t bufferLength = m_buffer.Length();

    83     size_t writeIndex = (*readIndex + delayFrames) % bufferLength;

    85     // Update caller's readIndex

    86     *readIndex = (*readIndex + numberOfFrames) % bufferLength;

    88     size_t framesAvailable = bufferLength - writeIndex;

    89     size_t numberOfFrames1 = std::min(numberOfFrames, framesAvailable);

    90     size_t numberOfFrames2 = numberOfFrames - numberOfFrames1;

    92     float* destination = m_buffer.Elements();

    94     bool isSafe = writeIndex <= bufferLength && numberOfFrames1 + writeIndex <= bufferLength && numberOfFrames2 <= bufferLength;

    95     MOZ_ASSERT(isSafe);

    96     if (!isSafe)

    97         return 0;

    99     AudioBufferAddWithScale(source, 1.0f, destination + writeIndex, numberOfFrames1);

   101     // Handle wrap-around if necessary

   102     if (numberOfFrames2 > 0) {

   103         AudioBufferAddWithScale(source + numberOfFrames1, 1.0f, destination, numberOfFrames2);

   104     }

   106     return writeIndex;

   107 }

   109 void ReverbAccumulationBuffer::reset()

   110 {

   111     PodZero(m_buffer.Elements(), m_buffer.Length());

   112     m_readIndex = 0;

   113     m_readTimeFrame = 0;

   114 }

   116 } // namespace WebCore

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