third_party/WebKit/Source/platform/audio/ReverbInputBuffer.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;
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 */

#ifndef ReverbInputBuffer_h
#define ReverbInputBuffer_h

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

namespace blink {

// ReverbInputBuffer is used to buffer input samples for deferred processing by
// the background threads.
class PLATFORM_EXPORT ReverbInputBuffer {
  DISALLOW_NEW();
  WTF_MAKE_NONCOPYABLE(ReverbInputBuffer);

 public:
  ReverbInputBuffer(size_t length);

  // The realtime audio thread keeps writing samples here.
  // The assumption is that the buffer's length is evenly divisible by
  // numberOfFrames (for nearly all cases this will be fine).
  // FIXME: remove numberOfFrames restriction...
  void Write(const float* source_p, size_t number_of_frames);

  // Background threads can call this to check if there's anything to read...
  size_t WriteIndex() const { return AcquireLoad(&write_index_); }
  void SetWriteIndex(size_t value) { ReleaseStore(&write_index_, value); }

  // The individual background threads read here (and hope that they can keep up
  // with the buffer writing).
  // readIndex is updated with the next readIndex to read from...
  // The assumption is that the buffer's length is evenly divisible by
  // numberOfFrames.
  // FIXME: remove numberOfFrames restriction...
  float* DirectReadFrom(int* read_index, size_t number_of_frames);

  void Reset();

 private:
  AudioFloatArray buffer_;

  // write_index_ can be accessed from several threads.  Only use the
  // getter and the setter to access it atomically.  Don't access
  // write_index_ directly!
  size_t write_index_;
};

}  // namespace blink

#endif  // ReverbInputBuffer_h