text: // Copyright 2013 Olivier Gillet.
  //
  // Author: Olivier Gillet (pichenettes@mutable-instruments.net)
  //
  // 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.
  // 
  // See http://creativecommons.org/licenses/MIT/ for more information.
  //
  // -----------------------------------------------------------------------------
  //
  // SVF used for the envelope follower filter bank.
  
  #ifndef STREAMS_SVF_H_
  #define STREAMS_SVF_H_
  
  #include "stmlib/stmlib.h"
  
  namespace streams {
  
  class Svf {
   public:
    Svf() { }
    ~Svf() { }
    
    void Init();
    
    void set_frequency(int16_t frequency) {
      dirty_ = dirty_ || (frequency_ != frequency);
      frequency_ = frequency;
    }
    
    void set_resonance(int16_t resonance) {
      resonance_ = resonance;
      dirty_ = true;
    }
    
    void Process(int32_t sample);
    inline int32_t lp() const { return lp_; }
    inline int32_t bp() const { return bp_; }
    inline int32_t hp() const { return hp_; }
    
   private:
    bool dirty_;
    
    int16_t frequency_;
    int16_t resonance_;
    
    int32_t f_;
    int32_t damp_;
  
    int32_t lp_;
    int32_t bp_;
    int32_t hp_;
    
    DISALLOW_COPY_AND_ASSIGN(Svf);
  };
  
  }  // namespace streams
  
  #endif  // STREAMS_SVF_H_
  