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      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 #ifndef ReverbAccumulationBuffer_h
     30 #define ReverbAccumulationBuffer_h
     31 
     32 #include "AudioArray.h"
     33 
     34 namespace WebCore {
     35 
     36 // ReverbAccumulationBuffer is a circular delay buffer with one client reading from it and multiple clients
     37 // writing/accumulating to it at different delay offsets from the read position.  The read operation will zero the memory
     38 // just read from the buffer, so it will be ready for accumulation the next time around.
     39 class ReverbAccumulationBuffer {
     40 public:
     41     ReverbAccumulationBuffer(size_t length);
     42 
     43     // This will read from, then clear-out numberOfFrames
     44     void readAndClear(float* destination, size_t numberOfFrames);
     45 
     46     // Each ReverbConvolverStage will accumulate its output at the appropriate delay from the read position.
     47     // We need to pass in and update readIndex here, since each ReverbConvolverStage may be running in
     48     // a different thread than the realtime thread calling ReadAndClear() and maintaining m_readIndex
     49     // Returns the writeIndex where the accumulation took place
     50     int accumulate(float* source, size_t numberOfFrames, int* readIndex, size_t delayFrames);
     51 
     52     size_t readIndex() const { return m_readIndex; }
     53     void updateReadIndex(int* readIndex, size_t numberOfFrames) const;
     54 
     55     size_t readTimeFrame() const { return m_readTimeFrame; }
     56 
     57     void reset();
     58 
     59 private:
     60     AudioFloatArray m_buffer;
     61     size_t m_readIndex;
     62     size_t m_readTimeFrame; // for debugging (frame on continuous timeline)
     63 };
     64 
     65 } // namespace WebCore
     66 
     67 #endif // ReverbAccumulationBuffer_h
     68