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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 #ifndef AudioFIFO_h |
| 30 #define AudioFIFO_h |
| 31 |
| 32 #include "platform/audio/AudioBus.h" |
| 33 #include "wtf/Allocator.h" |
| 34 |
| 35 namespace blink { |
| 36 |
| 37 class AudioFIFO { |
| 38 USING_FAST_MALLOC(AudioFIFO); |
| 39 WTF_MAKE_NONCOPYABLE(AudioFIFO); |
| 40 |
| 41 public: |
| 42 // Create a FIFO large enough to hold |fifoLength| frames of data of |
| 43 // |numberOfChannels| channels. |
| 44 AudioFIFO(unsigned numberOfChannels, size_t fifoLength); |
| 45 |
| 46 // Push the data from the bus into the FIFO. |
| 47 void push(const AudioBus*); |
| 48 |
| 49 // Consume |framesToConsume| frames of data from the FIFO and put them in |
| 50 // |destination|. The corresponding frames are removed from the FIFO. |
| 51 void consume(AudioBus* destination, size_t framesToConsume); |
| 52 |
| 53 // Number of frames of data that are currently in the FIFO. |
| 54 size_t framesInFifo() const { return m_framesInFifo; } |
| 55 |
| 56 private: |
| 57 // Update the FIFO index by the step, with appropriate wrapping around the |
| 58 // endpoint. |
| 59 int updateIndex(int index, int step) { return (index + step) % m_fifoLength; } |
| 60 |
| 61 void findWrapLengths(size_t index, |
| 62 size_t providerSize, |
| 63 size_t& part1Length, |
| 64 size_t& part2Length); |
| 65 |
| 66 // The FIFO itself. In reality, the FIFO is a circular buffer. |
| 67 RefPtr<AudioBus> m_fifoAudioBus; |
| 68 |
| 69 // The total available space in the FIFO. |
| 70 size_t m_fifoLength; |
| 71 |
| 72 // The number of actual elements in the FIFO |
| 73 size_t m_framesInFifo; |
| 74 |
| 75 // Where to start reading from the FIFO. |
| 76 size_t m_readIndex; |
| 77 |
| 78 // Where to start writing to the FIFO. |
| 79 size_t m_writeIndex; |
| 80 }; |
| 81 |
| 82 } // namespace blink |
| 83 |
| 84 #endif // AudioFIFO.h |
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