iir_2nd.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_2ND
#define IIR_2ND
namespace SPUC {








template <class Numeric> class iir_2nd
{
    protected:   
        Numeric b0,b1,b2;                    
        Numeric a1,a2;
        Numeric in[3];
        Numeric out[3]; 
        
    public:
        iir_2nd(Numeric B0, Numeric B1, Numeric B2, Numeric A1, Numeric A2) : b0(B0), b1(B1), b2(B2), a1(A1), a2(A2) {
                in[0] = in[1] = in[2] = out[2] = out[1] = out[0] = 0 ; }
        iir_2nd(Numeric A1=0, Numeric A2=0) : b0(1), b1(2), b2(1), a1(A1), a2(A2) {
                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 set_a(Numeric A1, Numeric A2) { a1=A1; a2=A2;}
                void set_b(Numeric A1, Numeric A2) { b1=A1; b2=A2;}
                void set_coeff(Numeric A1, Numeric A2) { a1=A1; a2=A2;}

iir_2nd(const char* file)
{
        FILE *iirf = fopen(file,"r"); 
        fscanf(iirf,"%lf %lf %lf %lf %lf",&b0,&b1,&b2,&a1,&a2);
        fclose(iirf);
        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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