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