text: /*
   *  Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree. An additional intellectual property rights grant can be found
   *  in the file PATENTS.  All contributing project authors may
   *  be found in the AUTHORS file in the root of the source tree.
   */
  
  #ifndef MODULES_AUDIO_PROCESSING_AEC3_SPECTRUM_BUFFER_H_
  #define MODULES_AUDIO_PROCESSING_AEC3_SPECTRUM_BUFFER_H_
  
  #include <stddef.h>
  
  #include <array>
  #include <vector>
  
  #include "aec3_common.h"
  #include "checks.h"
  
  namespace webrtc {
  
  // Struct for bundling a circular buffer of one dimensional vector objects
  // together with the read and write indices.
  struct SpectrumBuffer {
    SpectrumBuffer(size_t size, size_t num_channels);
    ~SpectrumBuffer();
  
    int IncIndex(int index) const {
      RTC_DCHECK_EQ(buffer.size(), static_cast<size_t>(size));
      return index < size - 1 ? index + 1 : 0;
    }
  
    int DecIndex(int index) const {
      RTC_DCHECK_EQ(buffer.size(), static_cast<size_t>(size));
      return index > 0 ? index - 1 : size - 1;
    }
  
    int OffsetIndex(int index, int offset) const {
      RTC_DCHECK_GE(size, offset);
      RTC_DCHECK_EQ(buffer.size(), static_cast<size_t>(size));
      RTC_DCHECK_GE(size + index + offset, 0);
      return (size + index + offset) % size;
    }
  
    void UpdateWriteIndex(int offset) { write = OffsetIndex(write, offset); }
    void IncWriteIndex() { write = IncIndex(write); }
    void DecWriteIndex() { write = DecIndex(write); }
    void UpdateReadIndex(int offset) { read = OffsetIndex(read, offset); }
    void IncReadIndex() { read = IncIndex(read); }
    void DecReadIndex() { read = DecIndex(read); }
  
    const int size;
    std::vector<std::vector<std::array<float, kFftLengthBy2Plus1>>> buffer;
    int write = 0;
    int read = 0;
  };
  
  }  // namespace webrtc
  
  #endif  // MODULES_AUDIO_PROCESSING_AEC3_SPECTRUM_BUFFER_H_
  