1 /*
2  *  Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
3  *
4  *  Use of this source code is governed by a BSD-style license
5  *  that can be found in the LICENSE file in the root of the source
6  *  tree. An additional intellectual property rights grant can be found
7  *  in the file PATENTS.  All contributing project authors may
8  *  be found in the AUTHORS file in the root of the source tree.
9  */
10 
11 #ifndef MODULES_AUDIO_PROCESSING_NS_NS_FFT_H_
12 #define MODULES_AUDIO_PROCESSING_NS_NS_FFT_H_
13 
14 #include <vector>
15 
16 #include "api/array_view.h"
17 #include "modules/audio_processing/ns/ns_common.h"
18 
19 namespace webrtc {
20 
21 // Wrapper class providing 256 point FFT functionality.
22 class NrFft {
23  public:
24   NrFft();
25   NrFft(const NrFft&) = delete;
26   NrFft& operator=(const NrFft&) = delete;
27 
28   // Transforms the signal from time to frequency domain.
29   void Fft(rtc::ArrayView<float, kFftSize> time_data,
30            rtc::ArrayView<float, kFftSize> real,
31            rtc::ArrayView<float, kFftSize> imag);
32 
33   // Transforms the signal from frequency to time domain.
34   void Ifft(rtc::ArrayView<const float> real,
35             rtc::ArrayView<const float> imag,
36             rtc::ArrayView<float> time_data);
37 
38  private:
39   std::vector<size_t> bit_reversal_state_;
40   std::vector<float> tables_;
41 };
42 
43 }  // namespace webrtc
44 
45 #endif  // MODULES_AUDIO_PROCESSING_NS_NS_FFT_H_
46