bass_drum.h
// Copyright 2013 Olivier Gillet.
//
// Author: Olivier Gillet (ol.gillet@gmail.com)
//
// 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.
//
// -----------------------------------------------------------------------------
//
// 808-style bass drum.
 
#ifndef PEAKS_DRUMS_BASS_DRUM_H_
#define PEAKS_DRUMS_BASS_DRUM_H_

#include "stmlib/stmlib.h"

#include "peaks/drums/svf.h"
#include "peaks/drums/excitation.h"

#include "peaks/gate_processor.h"

namespace peaks {

class BassDrum {
 public:
  BassDrum() { }
  ~BassDrum() { }

  void Init();
  void Process(const GateFlags* gate_flags, int16_t* out, size_t size);
  
  void Configure(uint16_t* parameter, ControlMode control_mode) {
    if (control_mode == CONTROL_MODE_HALF) {
      set_frequency(0);
      set_punch(40000);
      set_tone(8192 + (parameter[0] >> 1));
      set_decay(parameter[1]);
    } else {
      set_frequency(parameter[0] - 32768);
      set_punch(parameter[1]);
      set_tone(parameter[2]);
      set_decay(parameter[3]);
    }
  }
  
  void set_frequency(int16_t frequency) {
    frequency_ = (31 << 7) + (static_cast<int32_t>(frequency) * 896 >> 15);
  }
  
  void set_decay(uint16_t decay) {
    uint32_t scaled;
    uint32_t squared;
    scaled = 65535 - decay;
    squared = scaled * scaled >> 16;
    scaled = squared * scaled >> 18;
    resonator_.set_resonance(32768 - 128 - scaled);
  }
  
  void set_tone(uint16_t tone) {
    uint32_t coefficient = tone;
    coefficient = coefficient * coefficient >> 16;
    lp_coefficient_ = 512 + (coefficient >> 2) * 3;
  }

  void set_punch(uint16_t punch) {
    resonator_.set_punch(punch * punch >> 16);
  }

 private:
  Excitation pulse_up_;
  Excitation pulse_down_;
  Excitation attack_fm_;
  Svf resonator_;

  int32_t frequency_;
  int32_t lp_coefficient_;
  int32_t lp_state_;

  DISALLOW_COPY_AND_ASSIGN(BassDrum);
};

}  // namespace peaks

#endif  // PEAKS_DRUMS_BASS_DRUM_H_