00001 // 00002 // Copyright(c) 1993-1996 Tony Kirke 00003 // author="Tony Kirke" * 00004 /* 00005 * SPUC - Signal processing using C++ - A DSP library 00006 * 00007 * This program is free software; you can redistribute it and/or modify 00008 * it under the terms of the GNU General Public License as published by 00009 * the Free Software Foundation; either version 2, or (at your option) 00010 * any later version. 00011 * 00012 * This program is distributed in the hope that it will be useful, 00013 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00015 * GNU General Public License for more details. 00016 * 00017 * You should have received a copy of the GNU General Public License 00018 * along with this program; if not, write to the Free Software 00019 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 00020 */ 00021 #ifndef IIR_LPF 00022 #define IIR_LPF 00023 namespace SPUC { 00026 // 00033 template <class Numeric> class iir_lpf 00034 { 00035 protected: 00036 double gain; 00037 double a; 00038 Numeric out; 00039 Numeric previous_out; 00040 Numeric previous_in; 00041 00042 public: 00043 iir_lpf(double A=0) { 00044 gain = (1-A)/(A+1); 00045 a = A/(A+1); 00046 previous_in = previous_out = out = 0 ; } 00047 void set_coeff(double A) { gain=A;} 00049 iir_lpf(const char* file) 00050 { 00051 FILE *iirf = fopen(file,"r"); 00052 fscanf(iirf,"%lf",&gain); 00053 fclose(iirf); 00054 previous_in = previous_out = out = 0; 00055 } 00057 void print() { 00058 cout << "IIR B0 = " << a << ", "; 00059 cout << "A0 = " << gain << "\n"; 00060 } 00062 Numeric clock(Numeric input) { 00063 // Shift previous outputs and calculate new output */ 00064 out = gain*previous_out + a*(input+previous_in); 00065 previous_out = out; 00066 previous_in = input; 00067 return(out); 00068 } 00070 void reset() { 00071 previous_in = previous_out = out = 0; 00072 } 00073 }; 00074 } // namespace SPUC 00075 #endif
1.4.4