/*
 * Copyright (C) 2010 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
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 *     documentation and/or other materials provided with the distribution.
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 *     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
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#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_REVERB_ACCUMULATION_BUFFER_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_REVERB_ACCUMULATION_BUFFER_H_

#include "base/containers/span.h"
#include "third_party/blink/renderer/platform/audio/audio_array.h"
#include "third_party/blink/renderer/platform/wtf/allocator/allocator.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 ReverbAccumulationBuffer final {
  DISALLOW_NEW();

 public:
  explicit ReverbAccumulationBuffer(uint32_t length);
  ReverbAccumulationBuffer(const ReverbAccumulationBuffer&) = delete;
  ReverbAccumulationBuffer& operator=(const ReverbAccumulationBuffer&) = delete;

  // This will read from, then clear-out numberOfFrames
  void ReadAndClear(base::span<float> destination);

  // 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
  uint32_t Accumulate(base::span<const float> source,
                      uint32_t* read_index,
                      size_t delay_frames);

  void UpdateReadIndex(uint32_t* read_index, uint32_t number_of_frames) const;

  void Reset();

 private:
  AudioFloatArray buffer_;
  uint32_t read_index_;
};

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_REVERB_ACCUMULATION_BUFFER_H_