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      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)
    145