/
hysteresis_quantizer.h
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/
hysteresis_quantizer.h
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// Copyright 2015 Emilie Gillet.
//
// Author: Emilie Gillet (emilie.o.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.
//
// -----------------------------------------------------------------------------
//
// Quantize a float in [0, 1] to an integer in [0, num_steps[. Apply hysteresis
// to prevent jumps near the decision boundary.
#ifndef STMLIB_DSP_HYSTERESIS_QUANTIZER_H_
#define STMLIB_DSP_HYSTERESIS_QUANTIZER_H_
#include "stmlib/stmlib.h"
namespace stmlib {
class HysteresisQuantizer {
public:
HysteresisQuantizer() { }
~HysteresisQuantizer() { }
void Init() {
quantized_value_ = 0;
}
inline int Process(float value, int num_steps) {
return Process(value, num_steps, 0.25f);
}
inline int Process(float value, int num_steps, float hysteresis) {
return Process(0, value, num_steps, hysteresis);
}
inline int Process(int base, float value, int num_steps, float hysteresis) {
value *= static_cast<float>(num_steps - 1);
value += static_cast<float>(base);
float hysteresis_feedback = value > static_cast<float>(quantized_value_)
? -hysteresis
: hysteresis;
int q = static_cast<int>(value + hysteresis_feedback + 0.5f);
CONSTRAIN(q, 0, num_steps - 1);
quantized_value_ = q;
return q;
}
template<typename T>
const T& Lookup(const T* array, float value, int num_steps) {
return array[Process(value, num_steps)];
}
private:
int quantized_value_;
DISALLOW_COPY_AND_ASSIGN(HysteresisQuantizer);
};
// Note: currently refactoring this aspect of all Mutable Instruments modules.
// The codebase will progressively use only this class, at which point the other
// version will be deprecated
class HysteresisQuantizer2 {
public:
HysteresisQuantizer2() { }
~HysteresisQuantizer2() { }
void Init(int num_steps, float hysteresis, bool symmetric) {
num_steps_ = num_steps;
hysteresis_ = hysteresis;
scale_ = static_cast<float>(symmetric ? num_steps - 1 : num_steps);
offset_ = symmetric ? 0.0f : -0.5f;
quantized_value_ = 0;
}
inline int Process(float value) {
return Process(0, value);
}
inline int Process(int base, float value) {
value *= scale_;
value += offset_;
value += static_cast<float>(base);
float hysteresis_sign = value > static_cast<float>(quantized_value_)
? -1.0f
: +1.0f;
int q = static_cast<int>(value + hysteresis_sign * hysteresis_ + 0.5f);
CONSTRAIN(q, 0, num_steps_ - 1);
quantized_value_ = q;
return q;
}
template<typename T>
const T& Lookup(const T* array, float value) {
return array[Process(value)];
}
inline int num_steps() const {
return num_steps_;
}
inline int quantized_value() const {
return quantized_value_;
}
private:
int num_steps_;
float hysteresis_;
float scale_;
float offset_;
int quantized_value_;
DISALLOW_COPY_AND_ASSIGN(HysteresisQuantizer2);
};
} // namespace stmlib
#endif // STMLIB_DSP_HYSTERESIS_QUANTIZER_H_