core/bs2b.h

   1 /*-
   2  * Copyright (c) 2005 Boris Mikhaylov
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining
   5  * a copy of this software and associated documentation files (the
   6  * "Software"), to deal in the Software without restriction, including
   7  * without limitation the rights to use, copy, modify, merge, publish,
   8  * distribute, sublicense, and/or sell copies of the Software, and to
   9  * permit persons to whom the Software is furnished to do so, subject to
  10  * the following conditions:
  11  *
  12  * The above copyright notice and this permission notice shall be
  13  * included in all copies or substantial portions of the Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  16  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  17  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  18  * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
  19  * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  20  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  21  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  22  */
  23
  24 #ifndef CORE_BS2B_H
  25 #define CORE_BS2B_H
  26
  27 #include <array>
  28 #include <cstddef>
  29
  30 namespace Bs2b {
  31
  32 enum {
  33     /* Normal crossfeed levels */
  34     LowCLevel    = 1,
  35     MiddleCLevel = 2,
  36     HighCLevel   = 3,
  37
  38     /* Easy crossfeed levels */
  39     LowECLevel    = 4,
  40     MiddleECLevel = 5,
  41     HighECLevel   = 6,
  42
  43     DefaultCLevel = HighECLevel
  44 };
  45
  46 struct bs2b {
  47     int level{}; /* Crossfeed level */
  48     int srate{}; /* Sample rate (Hz) */
  49
  50     /* Lowpass IIR filter coefficients */
  51     float a0_lo{};
  52     float b1_lo{};
  53
  54     /* Highboost IIR filter coefficients */
  55     float a0_hi{};
  56     float a1_hi{};
  57     float b1_hi{};
  58
  59     /* Buffer of filter history
  60      * [0] - first channel, [1] - second channel
  61      */
  62     struct t_last_sample {
  63         float lo{};
  64         float hi{};
  65     };
  66     std::array<t_last_sample,2> history{};
  67
  68     /* Clear buffers and set new coefficients with new crossfeed level and
  69      * sample rate values.
  70      * level - crossfeed level of *Level enum values.
  71      * srate - sample rate by Hz.
  72      */
  73     void set_params(int level, int srate);
  74
  75     /* Return current crossfeed level value */
  76     [[nodiscard]] auto get_level() const noexcept -> int { return level; }
  77
  78     /* Return current sample rate value */
  79     [[nodiscard]] auto get_srate() const noexcept -> int { return srate; }
  80
  81     /* Clear buffer */
  82     void clear();
  83
  84     void cross_feed(float *Left, float *Right, std::size_t SamplesToDo);
  85 };
  86
  87 } // namespace Bs2b
  88
  89 #endif /* CORE_BS2B_H */