text: /*-
   * Copyright (c) 2005 Boris Mikhaylov
   *
   * Permission is hereby granted, free of charge, to any person obtaining
   * a copy of this software and associated documentation files (the
   * "Software"), to deal in the Software without restriction, including
   * without limitation the rights to use, copy, modify, merge, publish,
   * distribute, sublicense, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so, subject to
   * the following conditions:
   *
   * The above copyright notice and this permission notice shall be
   * included in all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
   * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
   * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
   * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   */
  
  #ifndef BS2B_H
  #define BS2B_H
  
  /* Number of crossfeed levels */
  #define BS2B_CLEVELS           3
  
  /* Normal crossfeed levels */
  #define BS2B_HIGH_CLEVEL       3
  #define BS2B_MIDDLE_CLEVEL     2
  #define BS2B_LOW_CLEVEL        1
  
  /* Easy crossfeed levels */
  #define BS2B_HIGH_ECLEVEL      BS2B_HIGH_CLEVEL    + BS2B_CLEVELS
  #define BS2B_MIDDLE_ECLEVEL    BS2B_MIDDLE_CLEVEL  + BS2B_CLEVELS
  #define BS2B_LOW_ECLEVEL       BS2B_LOW_CLEVEL     + BS2B_CLEVELS
  
  /* Default crossfeed levels */
  #define BS2B_DEFAULT_CLEVEL    BS2B_HIGH_ECLEVEL
  /* Default sample rate (Hz) */
  #define BS2B_DEFAULT_SRATE     44100
  
  #ifdef __cplusplus
  extern "C" {
  #endif /* __cplusplus */
  
  struct bs2b {
      int level;  /* Crossfeed level */
      int srate;   /* Sample rate (Hz) */
  
      /* Lowpass IIR filter coefficients */
      double a0_lo;
      double b1_lo;
  
      /* Highboost IIR filter coefficients */
      double a0_hi;
      double a1_hi;
      double b1_hi;
  
      /* Global gain against overloading */
      float gain;
  
      /* Buffer of last filtered sample.
       * [0] - first channel, [1] - second channel
       */
      struct t_last_sample {
          double asis[2];
          double lo[2];
          double hi[2];
      } last_sample;
  };
  
  /* Clear buffers and set new coefficients with new crossfeed level value.
   * level - crossfeed level of *LEVEL values.
   */
  void bs2b_set_level(struct bs2b *bs2b, int level);
  
  /* Return current crossfeed level value */
  int bs2b_get_level(struct bs2b *bs2b);
  
  /* Clear buffers and set new coefficients with new sample rate value.
   * srate - sample rate by Hz.
   */
  void bs2b_set_srate(struct bs2b *bs2b, int srate);
  
  /* Return current sample rate value */
  int bs2b_get_srate(struct bs2b *bs2b);
  
  /* Clear buffer */
  void bs2b_clear(struct bs2b *bs2b);
  
  /* Crossfeeds one stereo sample that are pointed by sample.
   * [0] - first channel, [1] - second channel.
   * Returns crossfided samle by sample pointer.
   */
  
  /* sample poits to floats */
  void bs2b_cross_feed(struct bs2b *bs2b, float *sample);
  
  #ifdef __cplusplus
  }    /* extern "C" */
  #endif /* __cplusplus */
  
  #endif /* BS2B_H */
  