GNU Radio 2.x: gr_single_pole_iir.h Source File

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# gr_single_pole_iir.h

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    00001 /* -*- c++ -*- */
    00002 /*
    00003  * Copyright 2002 Free Software Foundation, Inc.
    00004  *
    00005  * This file is part of GNU Radio
    00006  *
    00007  * GNU Radio 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  * GNU Radio 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 GNU Radio; see the file COPYING.  If not, write to
    00019  * the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
    00020  * Boston, MA 02111-1307, USA.
    00021  */
    00022 #ifndef _GR_SINGLE_POLE_IIR_H_
    00023 #define _GR_SINGLE_POLE_IIR_H_
    00024
    00025 #include <stdexcept>
    00026
    00030 template<class o_type, class i_type, class tap_type>
    00031 class gr_single_pole_iir {
    00032 public:
    00038   gr_single_pole_iir (tap_type alpha = 1.0)
    00039   {
    00040     d_prev_output = 0;
    00041     set_taps (alpha);
    00042   }
    00043
    00048   o_type filter (const i_type input);
    00049
    00054   void filterN (o_type output[], const i_type input[], unsigned long n);
    00055
    00059   void set_taps (tap_type alpha)
    00060   {
    00061     if (alpha < 0 || alpha > 1)
    00062       throw std::out_of_range ("Alpha must be in [0, 1]\n");
    00063
    00064     d_alpha = alpha;
    00065     d_one_minus_alpha = 1.0 - alpha;
    00066   }
    00067
    00069   void reset ()
    00070   {
    00071     d_prev_output = 0;
    00072   }
    00073
    00074   tap_type prev_output () { return d_prev_output; }
    00075
    00076 protected:
    00077   tap_type      d_alpha;
    00078   tap_type      d_one_minus_alpha;
    00079   tap_type      d_prev_output;
    00080 };
    00081
    00082
    00083 //
    00084 // general case.  We may want to specialize this
    00085 //
    00086 template<class o_type, class i_type, class tap_type>
    00087 o_type
    00088 gr_single_pole_iir<o_type, i_type, tap_type>::filter (const i_type input)
    00089 {
    00090   tap_type      output;
    00091
    00092   output = d_alpha * input + d_one_minus_alpha * d_prev_output;
    00093   d_prev_output = output;
    00094
    00095   return (o_type) output;
    00096 }
    00097
    00098
    00099 template<class o_type, class i_type, class tap_type>
    00100 void
    00101 gr_single_pole_iir<o_type, i_type, tap_type>::filterN (o_type output[],
    00102                                                        const i_type input[],
    00103                                                        unsigned long n)
    00104 {
    00105   for (unsigned i = 0; i < n; i++)
    00106     output[i] = filter (input[i]);
    00107 }
    00108
    00109
    00110 #endif /* _GR_SINGLE_POLE_IIR_H_ */