text: // Copyright 2015 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.
  //
  // -----------------------------------------------------------------------------
  //
  // Group of voices.
  
  #ifndef RINGS_DSP_PART_H_
  #define RINGS_DSP_PART_H_
  
  #include <algorithm>
  
  #include "stmlib/stmlib.h"
  #include "stmlib/dsp/cosine_oscillator.h"
  #include "stmlib/dsp/delay_line.h"
  
  #include "rings/dsp/dsp.h"
  #include "rings/dsp/fm_voice.h"
  #include "rings/dsp/fx/reverb.h"
  #include "rings/dsp/limiter.h"
  #include "rings/dsp/note_filter.h"
  #include "rings/dsp/patch.h"
  #include "rings/dsp/performance_state.h"
  #include "rings/dsp/plucker.h"
  #include "rings/dsp/resonator.h"
  #include "rings/dsp/string.h"
  
  namespace rings {
  
  enum ResonatorModel {
    RESONATOR_MODEL_MODAL,
    RESONATOR_MODEL_SYMPATHETIC_STRING,
    RESONATOR_MODEL_STRING,
    
    // Bonus!
    RESONATOR_MODEL_FM_VOICE,
    RESONATOR_MODEL_SYMPATHETIC_STRING_QUANTIZED,
    RESONATOR_MODEL_STRING_AND_REVERB,
    RESONATOR_MODEL_LAST
  };
  
  const int32_t kMaxPolyphony = 4;
  const int32_t kNumStrings = kMaxPolyphony * 2;
  
  class Part {
   public:
    Part() { }
    ~Part() { }
    
    void Init(uint16_t* reverb_buffer);
    
    void Process(
        const PerformanceState& performance_state,
        const Patch& patch,
        const float* in,
        float* out,
        float* aux,
        size_t size);
  
    inline bool bypass() const { return bypass_; }
    inline void set_bypass(bool bypass) { bypass_ = bypass; }
  
    inline int32_t polyphony() const { return polyphony_; }
    inline void set_polyphony(int32_t polyphony) {
      int32_t old_polyphony = polyphony_;
      polyphony_ = std::min(polyphony, kMaxPolyphony);
      for (int32_t i = old_polyphony; i < polyphony_; ++i) {
        note_[i] = note_[0] + i * 0.05f;
      }
      dirty_ = true;
    }
    
    inline ResonatorModel model() const { return model_; }
    inline void set_model(ResonatorModel model) {
      if (model != model_) {
        model_ = model;
        dirty_ = true;
      }
    }
  
   private:
    void ConfigureResonators();
    void RenderModalVoice(
        int32_t voice,
        const PerformanceState& performance_state,
        const Patch& patch,
        float frequency,
        float filter_cutoff,
        size_t size);
    void RenderStringVoice(
        int32_t voice,
        const PerformanceState& performance_state,
        const Patch& patch,
        float frequency,
        float filter_cutoff,
        size_t size);
    void RenderFMVoice(
        int32_t voice,
        const PerformanceState& performance_state,
        const Patch& patch,
        float frequency,
        float filter_cutoff,
        size_t size);
    
  
    inline float Squash(float x) const {
      if (x < 0.5f) {
        x *= 2.0f;
        x *= x;
        x *= x;
        x *= x;
        x *= x;
        x *= 0.5f;
      } else {
        x = 2.0f - 2.0f * x;
        x *= x;
        x *= x;
        x *= x;
        x *= x;
        x = 1.0f - 0.5f * x;
      }
      return x;
    }
  
    void ComputeSympatheticStringsNotes(
        float tonic,
        float note,
        float parameter,
        float* destination,
        size_t num_strings);
    
    bool bypass_;
    bool dirty_;
  
    ResonatorModel model_;
  
    int32_t num_voices_;
    int32_t active_voice_;
    uint32_t step_counter_;
    int32_t polyphony_;
    
    Resonator resonator_[kMaxPolyphony];
    String string_[kNumStrings];
    stmlib::CosineOscillator lfo_[kNumStrings];
    FMVoice fm_voice_[kMaxPolyphony];
    
    stmlib::Svf excitation_filter_[kMaxPolyphony];
    stmlib::DCBlocker dc_blocker_[kMaxPolyphony];
    Plucker plucker_[kMaxPolyphony];
  
    float note_[kMaxPolyphony];
    NoteFilter note_filter_;
    
    float resonator_input_[kMaxBlockSize];
    float sympathetic_resonator_input_[kMaxBlockSize];
    float noise_burst_buffer_[kMaxBlockSize];
    
    float out_buffer_[kMaxBlockSize];
    float aux_buffer_[kMaxBlockSize];
    
    Reverb reverb_;
    Limiter limiter_;
    
    static float model_gains_[RESONATOR_MODEL_LAST];
    
    DISALLOW_COPY_AND_ASSIGN(Part);
  };
  
  }  // namespace rings
  
  #endif  // RINGS_DSP_PART_H_
  