third_party/blink/renderer/platform/audio/reverb_input_buffer.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
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_REVERB_INPUT_BUFFER_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_REVERB_INPUT_BUFFER_H_

#include <atomic>
#include "third_party/blink/renderer/platform/audio/audio_array.h"
#include "third_party/blink/renderer/platform/wtf/allocator/allocator.h"

namespace blink {

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

 public:
  explicit ReverbInputBuffer(size_t length);
  ReverbInputBuffer(const ReverbInputBuffer&) = delete;
  ReverbInputBuffer& operator=(const ReverbInputBuffer&) = delete;

  // 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 write_index_.load(std::memory_order_acquire);
  }

  // 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(size_t* read_index, size_t number_of_frames);

  void Reset();

 private:
  void SetWriteIndex(size_t new_index) {
    write_index_.store(new_index, std::memory_order_release);
  }

  AudioFloatArray buffer_;

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

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_REVERB_INPUT_BUFFER_H_