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_UTILITY_PFFFT_WRAPPER_H_
12 #define MODULES_AUDIO_PROCESSING_UTILITY_PFFFT_WRAPPER_H_
13 
14 #include <memory>
15 
16 #include "api/array_view.h"
17 
18 // Forward declaration.
19 struct PFFFT_Setup;
20 
21 namespace webrtc {
22 
23 // Pretty-Fast Fast Fourier Transform (PFFFT) wrapper class.
24 // Not thread safe.
25 class Pffft {
26  public:
27   enum class FftType { kReal, kComplex };
28 
29   // 1D floating point buffer used as input/output data type for the FFT ops.
30   // It must be constructed using Pffft::CreateBuffer().
31   class FloatBuffer {
32    public:
33     FloatBuffer(const FloatBuffer&) = delete;
34     FloatBuffer& operator=(const FloatBuffer&) = delete;
35     ~FloatBuffer();
36 
37     rtc::ArrayView<const float> GetConstView() const;
38     rtc::ArrayView<float> GetView();
39 
40    private:
41     friend class Pffft;
42     FloatBuffer(size_t fft_size, FftType fft_type);
const_data()43     const float* const_data() const { return data_; }
data()44     float* data() { return data_; }
size()45     size_t size() const { return size_; }
46 
47     const size_t size_;
48     float* const data_;
49   };
50 
51   // TODO(https://crbug.com/webrtc/9577): Consider adding a factory and making
52   // the ctor private.
53   // static std::unique_ptr<Pffft> Create(size_t fft_size,
54   // FftType fft_type); Ctor. |fft_size| must be a supported size (see
55   // Pffft::IsValidFftSize()). If not supported, the code will crash.
56   Pffft(size_t fft_size, FftType fft_type);
57   Pffft(const Pffft&) = delete;
58   Pffft& operator=(const Pffft&) = delete;
59   ~Pffft();
60 
61   // Returns true if the FFT size is supported.
62   static bool IsValidFftSize(size_t fft_size, FftType fft_type);
63 
64   // Returns true if SIMD code optimizations are being used.
65   static bool IsSimdEnabled();
66 
67   // Creates a buffer of the right size.
68   std::unique_ptr<FloatBuffer> CreateBuffer() const;
69 
70   // TODO(https://crbug.com/webrtc/9577): Overload with rtc::ArrayView args.
71   // Computes the forward fast Fourier transform.
72   void ForwardTransform(const FloatBuffer& in, FloatBuffer* out, bool ordered);
73   // Computes the backward fast Fourier transform.
74   void BackwardTransform(const FloatBuffer& in, FloatBuffer* out, bool ordered);
75 
76   // Multiplies the frequency components of |fft_x| and |fft_y| and accumulates
77   // them into |out|. The arrays must have been obtained with
78   // ForwardTransform(..., /*ordered=*/false) - i.e., |fft_x| and |fft_y| must
79   // not be ordered.
80   void FrequencyDomainConvolve(const FloatBuffer& fft_x,
81                                const FloatBuffer& fft_y,
82                                FloatBuffer* out,
83                                float scaling = 1.f);
84 
85  private:
86   const size_t fft_size_;
87   const FftType fft_type_;
88   PFFFT_Setup* pffft_status_;
89   float* const scratch_buffer_;
90 };
91 
92 }  // namespace webrtc
93 
94 #endif  // MODULES_AUDIO_PROCESSING_UTILITY_PFFFT_WRAPPER_H_
95