third_party/WebKit/Source/platform/audio/AudioFIFO.cpp

   1 /*
   2  * Copyright (C) 2012 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 "config.h"
  30
  31 #if ENABLE(WEB_AUDIO)
  32
  33 #include "platform/audio/AudioFIFO.h"
  34
  35 namespace blink {
  36
  37 AudioFIFO::AudioFIFO(unsigned numberOfChannels, size_t fifoLength)
  38     : m_fifoAudioBus(AudioBus::create(numberOfChannels, fifoLength))
  39     , m_fifoLength(fifoLength)
  40     , m_framesInFifo(0)
  41     , m_readIndex(0)
  42     , m_writeIndex(0)
  43 {
  44 }
  45
  46 void AudioFIFO::consume(AudioBus* destination, size_t framesToConsume)
  47 {
  48     bool isGood = destination && (framesToConsume <= m_fifoLength) && (framesToConsume <= m_framesInFifo) && (destination->length() >= framesToConsume);
  49     ASSERT(isGood);
  50     if (!isGood)
  51         return;
  52
  53     // Copy the requested number of samples to the destination.
  54
  55     size_t part1Length;
  56     size_t part2Length;
  57     findWrapLengths(m_readIndex, framesToConsume, part1Length, part2Length);
  58
  59     size_t numberOfChannels = m_fifoAudioBus->numberOfChannels();
  60
  61     for (size_t channelIndex = 0; channelIndex < numberOfChannels; ++channelIndex) {
  62         float* destinationData = destination->channel(channelIndex)->mutableData();
  63         const float* sourceData = m_fifoAudioBus->channel(channelIndex)->data();
  64
  65         bool isCopyGood = ((m_readIndex < m_fifoLength)
  66                            && (m_readIndex + part1Length) <= m_fifoLength
  67                            && (part1Length <= destination->length())
  68                            && (part1Length + part2Length) <= destination->length());
  69         ASSERT(isCopyGood);
  70         if (!isCopyGood)
  71             return;
  72
  73         memcpy(destinationData, sourceData + m_readIndex, part1Length * sizeof(*sourceData));
  74         // Handle wrap around of the FIFO, if needed.
  75         if (part2Length)
  76             memcpy(destinationData + part1Length, sourceData, part2Length * sizeof(*sourceData));
  77     }
  78     m_readIndex = updateIndex(m_readIndex, framesToConsume);
  79     ASSERT(m_framesInFifo >= framesToConsume);
  80     m_framesInFifo -= framesToConsume;
  81 }
  82
  83 void AudioFIFO::push(const AudioBus* sourceBus)
  84 {
  85     // Copy the sourceBus into the FIFO buffer.
  86
  87     bool isGood = sourceBus && (m_framesInFifo + sourceBus->length() <= m_fifoLength);
  88     if (!isGood)
  89         return;
  90
  91     size_t sourceLength = sourceBus->length();
  92     size_t part1Length;
  93     size_t part2Length;
  94     findWrapLengths(m_writeIndex, sourceLength, part1Length, part2Length);
  95
  96     size_t numberOfChannels = m_fifoAudioBus->numberOfChannels();
  97
  98     for (size_t channelIndex = 0; channelIndex < numberOfChannels; ++channelIndex) {
  99         float* destination = m_fifoAudioBus->channel(channelIndex)->mutableData();
 100         const float* source = sourceBus->channel(channelIndex)->data();
 101
 102         bool isCopyGood = ((m_writeIndex < m_fifoLength)
 103                            && (m_writeIndex + part1Length) <= m_fifoLength
 104                            && part2Length < m_fifoLength
 105                            && part1Length + part2Length <= sourceLength);
 106         ASSERT(isCopyGood);
 107         if (!isCopyGood)
 108             return;
 109
 110         memcpy(destination + m_writeIndex, source, part1Length * sizeof(*destination));
 111
 112         // Handle wrap around of the FIFO, if needed.
 113         if (part2Length)
 114             memcpy(destination, source + part1Length, part2Length * sizeof(*destination));
 115     }
 116
 117     m_framesInFifo += sourceLength;
 118     ASSERT(m_framesInFifo <= m_fifoLength);
 119     m_writeIndex = updateIndex(m_writeIndex, sourceLength);
 120 }
 121
 122 void AudioFIFO::findWrapLengths(size_t index, size_t size, size_t& part1Length, size_t& part2Length)
 123 {
 124     ASSERT_WITH_SECURITY_IMPLICATION(index < m_fifoLength && size <= m_fifoLength);
 125     if (index < m_fifoLength && size <= m_fifoLength) {
 126         if (index + size > m_fifoLength) {
 127             // Need to wrap. Figure out the length of each piece.
 128             part1Length = m_fifoLength - index;
 129             part2Length = size - part1Length;
 130         } else {
 131             // No wrap needed.
 132             part1Length = size;
 133             part2Length = 0;
 134         }
 135     } else {
 136         // Invalid values for index or size. Set the part lengths to zero so nothing is copied.
 137         part1Length = 0;
 138         part2Length = 0;
 139     }
 140 }
 141
 142 } // namespace blink
 143
 144 #endif // ENABLE(WEB_AUDIO)