iir_1st.h

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// 
// Copyright(c) 1993-1996 Tony Kirke
// author="Tony Kirke" *
/*
 * SPUC - Signal processing using C++ - A DSP library
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#ifndef IIR_1ST
#define IIR_1ST
#include <iostream>
using namespace std;
namespace SPUC {
template <class Numeric> class iir_1st
{
    protected:   
        double gain;                    
        Numeric out;
        Numeric previous_out;
                Numeric previous_in;
        
    public:
        iir_1st(double A=0) : gain(A) {
                previous_in = previous_out = out = 0 ; }
                void set_coeff(double A) { gain=A;}
                iir_1st(const char* file)
                  {
                        FILE *iirf = fopen(file,"r"); 
                        fscanf(iirf,"%lf",&gain);
                        fclose(iirf);
                        previous_in = previous_out = out = 0;
                  }             
                void print() {
                        cout << "IIR Coefficient gain = " << gain << "\n";
                }
                Numeric clock(Numeric input) {
                  // Shift previous outputs and calculate new output */
                  //    out = gain*previous_out + (1-gain)*input;
                  out = gain*previous_out + (input+previous_in);
                  previous_out = out;
                  previous_in = input;
                  return(out);
                }
                void reset() {
                  previous_in = previous_out = out = 0;
                }
};                                               
} // namespace SPUC 
#endif

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