smooth_random.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_SMOOTHRANDOM_H
#define DSY_SMOOTHRANDOM_H
 
#include "dsp.h"
#include <stdint.h>
#include <stdlib.h>
#ifdef __cplusplus
 
namespace daisysp
{
class SmoothRandomGenerator
{
  public:
    SmoothRandomGenerator() {}
    ~SmoothRandomGenerator() {}
 
    void Init(float sample_rate)
    {
        sample_rate_ = sample_rate;
 
        SetFreq(1.f);
        phase_    = 0.0f;
        from_     = 0.0f;
        interval_ = 0.0f;
    }
 
    float Process()
    {
        phase_ += frequency_;
        if(phase_ >= 1.0f)
        {
            phase_ -= 1.0f;
            from_ += interval_;
            interval_ = rand() * kRandFrac * 2.0f - 1.0f - from_;
        }
        float t = phase_ * phase_ * (3.0f - 2.0f * phase_);
        return from_ + interval_ * t;
    }
 
    void SetFreq(float freq)
    {
        freq       = freq / sample_rate_;
        frequency_ = fclamp(freq, 0.f, 1.f);
    }
 
  private:
    float frequency_;
    float phase_;
    float from_;
    float interval_;
 
    float sample_rate_;
 
    static constexpr float kRandFrac = 1.f / (float)RAND_MAX;
};
 
} // namespace daisysp
#endif
#endif