1 // Copyright 2019 Emilie Gillet. 2 // 3 // Author: Emilie Gillet (emilie.o.gillet@gmail.com) 4 // 5 // Permission is hereby granted, free of charge, to any person obtaining a copy 6 // of this software and associated documentation files (the "Software"), to deal 7 // in the Software without restriction, including without limitation the rights 8 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 9 // copies of the Software, and to permit persons to whom the Software is 10 // furnished to do so, subject to the following conditions: 11 // 12 // The above copyright notice and this permission notice shall be included in 13 // all copies or substantial portions of the Software. 14 // 15 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 16 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 17 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 18 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 19 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 20 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 21 // THE SOFTWARE. 22 // 23 // See http://creativecommons.org/licenses/MIT/ for more information. 24 // 25 // ----------------------------------------------------------------------------- 26 // 27 // Threshold type filter that filters out slow jumps of a value. 28 29 #ifndef STMLIB_DSP_HYSTERESIS_FILTER_H_ 30 #define STMLIB_DSP_HYSTERESIS_FILTER_H_ 31 32 #include "stmlib/stmlib.h" 33 34 namespace stmlib { 35 36 class HysteresisFilter { 37 public: HysteresisFilter()38 HysteresisFilter() { } ~HysteresisFilter()39 ~HysteresisFilter() { } 40 Init(float threshold)41 void Init(float threshold) { 42 value_ = 0.0f; 43 threshold_ = threshold; 44 } 45 Process(float value)46 inline float Process(float value) { 47 return Process(value, threshold_); 48 } 49 Process(float value,float threshold)50 inline float Process(float value, float threshold) { 51 if (threshold == 0.0f) { 52 value_ = value; 53 } else { 54 float error = value - value_; 55 if (error > threshold) { 56 value_ = value - threshold; 57 } else if (error < -threshold) { 58 value_ = value + threshold; 59 } 60 } 61 return value_; 62 } 63 value()64 inline float value() const { return value_; } 65 66 private: 67 float value_; 68 float threshold_; 69 70 DISALLOW_COPY_AND_ASSIGN(HysteresisFilter); 71 }; 72 73 } // namespace stmlib 74 75 #endif // STMLIB_DSP_HYSTERESIS_FILTER_H_ 76