iir_filter.h

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/*************************************************************************
 *  Copyright (C) 2016   Transmitterdan                                   *
 *                                                                        *
 *  This program is free software; you can redistribute it and/or modify  *
 *  it under the terms of the GNU General Public License as published by  *
 *  the Free Software Foundation; either version 2 of the License, or     *
 *  (at your option) any later version.                                   *
 *                                                                        *
 *  This program is distributed in the hope that it will be useful,       *
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *  GNU General Public License for more details.                          *
 *                                                                        *
 *  You should have received a copy of the GNU General Public License     *
 *  along with this program; if not, see <https://www.gnu.org/licenses/>. *
 *************************************************************************/
 
#if !defined(IIRFILTER_CLASS_HEADER)
#define IIRFILTER_CLASS_HEADER
 
// Filter types
enum {
  IIRFILTER_TYPE_LINEAR = 1 << 0,
  IIRFILTER_TYPE_DEG = 1 << 1,
  IIRFILTER_TYPE_RAD = 1 << 2
};
 
class IirFilter {
public:
  //    iirfilter() {setFC(0.5); type = IIRFILTER_TYPE_LINEAR; reset();};
 
  IirFilter(double fc = 0.5, int tp = IIRFILTER_TYPE_LINEAR);
  ~IirFilter() = default;
  double Filter(double data);   // Return filtered data given new data point
  void reset(double a = 0.0);   // Clear filter
  void SetFc(double fc = 0.1);  // Set cutoff frequency
  void SetType(int tp);         // Set type of filter (linear or angle type)
  double GetFc() const;         // Return cutoff frequency
  int GetType() const;          // Return type of filter
  double get() const;           // Return the current filtered data
 
protected:
  void UnwrapDeg(double deg);
  void UnwrapRad(double rad);
 
private:
  double a0;
  double b1;
  double accum;
  double oldDeg;
  double oldRad;
  int wraps;
  int type;
};
 
#endif  // IIRFILTER_CLASS_HEADER