iir_2ndhpf.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_2NDHPF
#define IIR_2NDHPF
namespace SPUC {
//
template <class Numeric> class iir_2ndhpf
{
    protected:   
        Numeric b0,b1,b2;                    
        Numeric a1,a2;
        Numeric in[3];
        Numeric out[3]; 
        
    public:
        iir_2ndhpf(Numeric A, Numeric B) {
                        double g = 1.0/(1.0+A+B);
                        b0 = g;
                        b1 = -2*g;
                        b2 = g;
                        a1 = 2*(A-1)*g;
                        a2 = (1-B+A)*g;
                in[0] = in[1] = in[2] = out[2] = out[1] = out[0] = 0 ; }
        void reset() {
                in[0] = in[1] = in[2] = out[2] = out[1] = out[0] = 0 ; } 
void print() {
    printf("IIR Coefficients B0 = %lf, B1 =  %lf, B2 = %lf",b0,b1,b2);
    printf(" A0 = 1, A1 = %lf, A2 = %lf\n",a1,a2);
}
Numeric clock(Numeric input) {
        // Shift inputs by one time sample and place new sample into array
        in[0] = in[1];
        in[1] = in[2];
        in[2] = input;
        // Shift previous outputs and calculate new output */
        out[0] = out[1];
        out[1] = out[2];
        out[2] = b0*in[2] + b1*in[1] + b2*in[0] - a1*out[1] - a2*out[0];
        return(out[2]);
}
};                                               
} // namespace SPUC 
#endif

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