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81 lines
2.7 KiB
C++
81 lines
2.7 KiB
C++
// Copyright 2015 Emilie Gillet.
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//
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// Author: Emilie Gillet (emilie.o.gillet@gmail.com)
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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//
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// See http://creativecommons.org/licenses/MIT/ for more information.
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//
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// -----------------------------------------------------------------------------
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//
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// Quantize a float in [0, 1] to an integer in [0, num_steps[. Apply hysteresis
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// to prevent jumps near the decision boundary.
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#ifndef STMLIB_DSP_HYSTERESIS_QUANTIZER_H_
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#define STMLIB_DSP_HYSTERESIS_QUANTIZER_H_
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#include <avrlib/avrlib.h>
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namespace pure_adsr {
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class HysteresisQuantizer {
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public:
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HysteresisQuantizer() { }
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~HysteresisQuantizer() { }
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void Init() {
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quantized_value_ = 0;
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}
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inline int Process(float value, int num_steps) {
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return Process(value, num_steps, 0.25f);
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}
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inline int Process(float value, int num_steps, float hysteresis) {
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return Process(0, value, num_steps, hysteresis);
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}
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inline int Process(int base, float value, int num_steps, float hysteresis) {
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value *= static_cast<float>(num_steps - 1);
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value += static_cast<float>(base);
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float hysteresis_feedback = value > static_cast<float>(quantized_value_)
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? -hysteresis
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: hysteresis;
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int q = static_cast<int>(value + hysteresis_feedback + 0.5f);
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if(q < 0) q = 0;
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if(q > num_steps - 1) q = num_steps - 1;
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quantized_value_ = q;
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return q;
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}
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template<typename T>
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const T& Lookup(const T* array, float value, int num_steps) {
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return array[Process(value, num_steps)];
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}
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private:
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int quantized_value_;
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DISALLOW_COPY_AND_ASSIGN(HysteresisQuantizer);
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};
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} // namespace stmlib
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#endif // STMLIB_DSP_HYSTERESIS_QUANTIZER_H_
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