KarplusString.h

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/*
Copyright (c) 2020 Electrosmith, Corp, Emilie Gillet
 
Use of this source code is governed by an MIT-style
license that can be found in the LICENSE file or at
https://opensource.org/licenses/MIT.
*/
 
#pragma once
#ifndef DSY_STRING_H
#define DSY_STRING_H
 
#include <stdint.h>
 
#include "Dynamics/crossfade.h"
#include "Utility/dcblock.h"
#include "Utility/delayline.h"
#include "Filters/onepole.h"
 
#ifdef __cplusplus
 
namespace daisysp
{
class String
{
  public:
    String() {}
    ~String() {}
 
    void Init(float sample_rate);
 
    void Reset();
 
    float Process(const float in);
 
    void SetFreq(float freq);
 
    void SetNonLinearity(float non_linearity_amount);
 
    void SetBrightness(float brightness);
 
    void SetDamping(float damping);
 
 
  private:
    static constexpr size_t kDelayLineSize = 1024;
 
    enum StringNonLinearity
    {
        NON_LINEARITY_CURVED_BRIDGE,
        NON_LINEARITY_DISPERSION
    };
 
    template <String::StringNonLinearity non_linearity>
    float ProcessInternal(const float in);
 
    DelayLine<float, kDelayLineSize>     string_;
    DelayLine<float, kDelayLineSize / 4> stretch_;
 
    float frequency_, non_linearity_amount_, brightness_, damping_;
 
    float sample_rate_;
 
    OnePole iir_damping_filter_;
 
    DcBlock dc_blocker_;
 
    CrossFade crossfade_;
 
    float dispersion_noise_;
    float curved_bridge_;
 
    // Very crappy linear interpolation upsampler used for low pitches that
    // do not fit the delay line. Rarely used.
    float src_phase_;
    float out_sample_[2];
};
} // namespace daisysp
#endif
#endif