QuantizationNoise.h

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/**********************************************************************************************************************
This file is part of the Control Toolbox (https://github.com/ethz-adrl/control-toolbox), copyright by ETH Zurich.
Licensed under the BSD-2 license (see LICENSE file in main directory)
**********************************************************************************************************************/

#pragma once

namespace ct {
namespace core {


class QuantizationNoise
{
public:
    enum QuantizationMethod
    {
        FLOOR, 
        ROUND  
    };


    QuantizationNoise(double bias = 0.0, double quantizationInterval = 1.0, QuantizationMethod method = FLOOR)
        : quantizationInterval_(quantizationInterval),
          quantizationRest_(1, 0.0),
          bias_(bias),
          quantizationMethod_(method)
    {
    }


    void noisify(double& value, size_t index = 0)
    {
        if (index >= quantizationRest_.size())
            quantizationRest_.resize(index, 0);

        double currentValue = value + quantizationRest_[index];
        double nQuantsDouble = currentValue / quantizationInterval_;
        int nQuants;

        switch (quantizationMethod_)
        {
            case FLOOR:
            {
                nQuants = std::floor(nQuantsDouble);
                break;
            }
            case ROUND:
            {
                nQuants = std::round(nQuantsDouble);
                break;
            }
            default:
            {
                throw std::runtime_error("Unknown quantization method chosen");
            }
        }

        double outputValue = nQuants * quantizationInterval_;

        quantizationRest_[index] = currentValue - outputValue;

        value = outputValue + bias_;
    }


    template <size_t size>
    void noisify(Eigen::Matrix<double, size, 1>& value)
    {
        for (size_t i = 0; i < size; i++)
        {
            noisify(value(i), i);
        }
    }


    void reset() { quantizationRest_.clear(); }
private:
    double quantizationInterval_;           
    std::vector<double> quantizationRest_;  
    double bias_;                           
    QuantizationMethod quantizationMethod_; 
};


}  // namespace ct
}  // namespace core