tor-browser

The Tor Browser
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ReverbAccumulationBuffer.cpp (4360B)

      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 */
     28 
     29 #include "ReverbAccumulationBuffer.h"
     30 
     31 #include <algorithm>
     32 
     33 #include "AudioNodeEngine.h"
     34 #include "mozilla/PodOperations.h"
     35 
     36 using namespace mozilla;
     37 
     38 namespace WebCore {
     39 
     40 ReverbAccumulationBuffer::ReverbAccumulationBuffer()
     41    : m_readIndex(0), m_readTimeFrame(0) {}
     42 
     43 bool ReverbAccumulationBuffer::allocate(size_t length) {
     44  if (!m_buffer.SetLength(length, fallible)) {
     45    return false;
     46  }
     47  PodZero(m_buffer.Elements(), length);
     48  return true;
     49 }
     50 
     51 void ReverbAccumulationBuffer::readAndClear(float* destination,
     52                                            size_t numberOfFrames) {
     53  size_t bufferLength = m_buffer.Length();
     54  bool isCopySafe =
     55      m_readIndex <= bufferLength && numberOfFrames <= bufferLength;
     56 
     57  MOZ_ASSERT(isCopySafe);
     58  if (!isCopySafe) return;
     59 
     60  size_t framesAvailable = bufferLength - m_readIndex;
     61  size_t numberOfFrames1 = std::min(numberOfFrames, framesAvailable);
     62  size_t numberOfFrames2 = numberOfFrames - numberOfFrames1;
     63 
     64  float* source = m_buffer.Elements();
     65  memcpy(destination, source + m_readIndex, sizeof(float) * numberOfFrames1);
     66  memset(source + m_readIndex, 0, sizeof(float) * numberOfFrames1);
     67 
     68  // Handle wrap-around if necessary
     69  if (numberOfFrames2 > 0) {
     70    memcpy(destination + numberOfFrames1, source,
     71           sizeof(float) * numberOfFrames2);
     72    memset(source, 0, sizeof(float) * numberOfFrames2);
     73  }
     74 
     75  m_readIndex = (m_readIndex + numberOfFrames) % bufferLength;
     76  m_readTimeFrame += numberOfFrames;
     77 }
     78 
     79 void ReverbAccumulationBuffer::accumulate(const float* source,
     80                                          size_t numberOfFrames,
     81                                          size_t* readIndex,
     82                                          size_t delayFrames) {
     83  size_t bufferLength = m_buffer.Length();
     84 
     85  size_t writeIndex = (*readIndex + delayFrames) % bufferLength;
     86 
     87  // Update caller's readIndex
     88  *readIndex = (*readIndex + numberOfFrames) % bufferLength;
     89 
     90  size_t framesAvailable = bufferLength - writeIndex;
     91  size_t numberOfFrames1 = std::min(numberOfFrames, framesAvailable);
     92  size_t numberOfFrames2 = numberOfFrames - numberOfFrames1;
     93 
     94  float* destination = m_buffer.Elements();
     95 
     96  bool isSafe = writeIndex <= bufferLength &&
     97                numberOfFrames1 + writeIndex <= bufferLength &&
     98                numberOfFrames2 <= bufferLength;
     99  MOZ_ASSERT(isSafe);
    100  if (!isSafe) return;
    101 
    102  AudioBufferAddWithScale(source, 1.0f, destination + writeIndex,
    103                          numberOfFrames1);
    104  if (numberOfFrames2 > 0) {
    105    AudioBufferAddWithScale(source + numberOfFrames1, 1.0f, destination,
    106                            numberOfFrames2);
    107  }
    108 }
    109 
    110 void ReverbAccumulationBuffer::reset() {
    111  PodZero(m_buffer.Elements(), m_buffer.Length());
    112  m_readIndex = 0;
    113  m_readTimeFrame = 0;
    114 }
    115 
    116 }  // namespace WebCore