third_party/WebKit/Source/platform/audio/ReverbAccumulationBuffer.h

/*
 * Copyright (C) 2010 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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 */

#ifndef ReverbAccumulationBuffer_h
#define ReverbAccumulationBuffer_h

#include "platform/PlatformExport.h"
#include "platform/audio/AudioArray.h"
#include "wtf/Allocator.h"
#include "wtf/Noncopyable.h"

namespace blink {

// ReverbAccumulationBuffer is a circular delay buffer with one client reading
// from it and multiple clients writing/accumulating to it at different delay
// offsets from the read position.  The read operation will zero the memory
// just read from the buffer, so it will be ready for accumulation the next
// time around.
class PLATFORM_EXPORT ReverbAccumulationBuffer {
  DISALLOW_NEW();
  WTF_MAKE_NONCOPYABLE(ReverbAccumulationBuffer);

 public:
  ReverbAccumulationBuffer(size_t length);

  // This will read from, then clear-out numberOfFrames
  void readAndClear(float* destination, size_t numberOfFrames);

  // Each ReverbConvolverStage will accumulate its output at the appropriate
  // delay from the read position.  We need to pass in and update readIndex
  // here, since each ReverbConvolverStage may be running in a different thread
  // than the realtime thread calling ReadAndClear() and maintaining
  // m_readIndex
  // Returns the writeIndex where the accumulation took place
  int accumulate(float* source,
                 size_t numberOfFrames,
                 int* readIndex,
                 size_t delayFrames);

  size_t readIndex() const { return m_readIndex; }
  void updateReadIndex(int* readIndex, size_t numberOfFrames) const;

  size_t readTimeFrame() const { return m_readTimeFrame; }

  void reset();

 private:
  AudioFloatArray m_buffer;
  size_t m_readIndex;
  size_t m_readTimeFrame;  // for debugging (frame on continuous timeline)
};

}  // namespace blink

#endif  // ReverbAccumulationBuffer_h