Fir1.h

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/*
License: MIT License (http://www.opensource.org/licenses/mit-license.php)
 
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The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
 
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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*/
 
/* (C) 2013-2021 Graeme Hattan & Bernd Porr */
 
#ifndef FIR1_H
#define FIR1_H
 
#include <stdio.h>
#include <vector>
 
class Fir1 {
public:
    template <unsigned nTaps> Fir1(const double (&_coefficients)[nTaps]) :
        coefficients(new double[nTaps]),
        buffer(new double[nTaps]()),
        taps(nTaps) {
        for(unsigned i=0;i<nTaps;i++) {
            coefficients[i] = _coefficients[i];
            buffer[i] = 0;
        }
    }
 
    Fir1(std::vector<double> _coefficients) {
        initWithVector(_coefficients);
    }
 
    Fir1(double *coefficients, unsigned number_of_taps);
 
    Fir1(const char* coeffFile, unsigned number_of_taps = 0);
 
    Fir1(unsigned number_of_taps);
 
    ~Fir1();
 
    
    inline double filter(double input) {
        const double *coeff     = coefficients;
        const double *const coeff_end = coefficients + taps;
        
        double *buf_val = buffer + offset;
        
        *buf_val = input;
        double output_ = 0;
        
        while(buf_val >= buffer)
            output_ += *buf_val-- * *coeff++;
        
        buf_val = buffer + taps-1;
        
        while(coeff < coeff_end)
            output_ += *buf_val-- * *coeff++;
        
        if(++offset >= taps)
            offset = 0;
        
        return output_;
    }
 
 
    inline void lms_update(double error) {
        double *coeff     = coefficients;
        const double *coeff_end = coefficients + taps;
    
        double *buf_val = buffer + offset;
        
        while(buf_val >= buffer) {
            *coeff++ += *buf_val-- * error * mu;
        }
        
        buf_val = buffer + taps-1;
        
        while(coeff < coeff_end) {
            *coeff++ += *buf_val-- * error * mu;
        }
    }
 
    void setLearningRate(double _mu) {mu = _mu;};
 
    double getLearningRate() {return mu;};
 
    void reset();
 
    void zeroCoeff();
 
    void getCoeff(double* coeff_data, unsigned number_of_taps) const;
 
    std::vector<double> getCoeffVector() const {
        return std::vector<double>(coefficients,coefficients+taps);
    }
 
    unsigned getTaps() {return taps;};
 
    inline double getTapInputPower() {
        double *buf_val = buffer;
        
        double p = 0;
        
        for(unsigned i = 0; i < taps; i++) {
            p += (*buf_val) * (*buf_val);
            buf_val++;
        }
    
        return p;
    }
 
private:
    void initWithVector(std::vector<double> _coefficients);
    
    double        *coefficients;
    double        *buffer;
    unsigned      taps;
    unsigned      offset = 0;
    double        mu = 0;
};
 
#endif