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VrIIRfilter.h

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00001 /* -*- Mode: c++ -*- */
00002 /*
00003  * Copyright 2001 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 /* -*- Mode: c++ -*- 
00023  *
00024  *  Copyright 1997 Massachusetts Institute of Technology
00025  * 
00026  *  Permission to use, copy, modify, distribute, and sell this software and its
00027  *  documentation for any purpose is hereby granted without fee, provided that
00028  *  the above copyright notice appear in all copies and that both that
00029  *  copyright notice and this permission notice appear in supporting
00030  *  documentation, and that the name of M.I.T. not be used in advertising or
00031  *  publicity pertaining to distribution of the software without specific,
00032  *  written prior permission.  M.I.T. makes no representations about the
00033  *  suitability of this software for any purpose.  It is provided "as is"
00034  *  without express or implied warranty.
00035  * 
00036  */
00037 
00038 
00039 #ifndef _VrIIRFILTER_H_
00040 #define _VrIIRFILTER_H_
00041 
00042 #include <VrSigProc.h>
00043 
00044 template<class iType,class oType> 
00045 class VrIIRfilter : public VrSigProc {
00046 protected:
00047   int order,offset;
00048   double *Btaps, *Ataps;
00049   iType *input_hist;
00050   oType *output_hist;
00051   float gain;
00052 
00053 public: 
00054   virtual int work(VrSampleRange output, void *ao[],
00055                 VrSampleRange inputs[], void *ai[]);
00056   virtual void initialize();
00057   VrIIRfilter(int,double *, double *, float);
00058   ~VrIIRfilter();
00059 };
00060 
00061 template<class iType,class oType> int
00062 VrIIRfilter<iType,oType>::work(VrSampleRange output, void *ao[],
00063                 VrSampleRange inputs[], void *ai[])
00064 {
00065   oType result;
00066   for (unsigned int sample=0;sample<output.size;sample++) 
00067   {
00068         input_hist[(sample + offset)% order] = ((iType **)ai)[0][sample];
00069         result = Btaps[0] * ((iType **)ai)[0][sample];
00070 
00071         for (int tap=1; tap < order; tap++) 
00072                 result += (Btaps[tap] * input_hist[(sample + offset + order - tap)%order]) 
00073                         + (Ataps[tap] * output_hist[(sample + offset + order - tap)%order]);
00074         ((oType **)ao)[0][sample] = gain * result;
00075         output_hist[(sample + offset) % order] = result;
00076   }
00077   offset = (offset + output.size) % order;
00078   return output.size;
00079 }
00080 
00081 
00082 template<class iType,class oType> 
00083 VrIIRfilter<iType,oType>::VrIIRfilter(int ord, double *intaps, double *outtaps, float gain)
00084   :VrSigProc(1, sizeof(iType), sizeof(oType)), order(ord),offset(0),gain(gain)
00085 {
00086   Ataps = new double[order];
00087   Btaps = new double[order];
00088   input_hist = new iType[order];
00089   output_hist = new oType[order];
00090 
00091   for(int i = 0; i<order; i++)
00092   {
00093         input_hist[i] = 0; output_hist[i] = 0;
00094         Btaps[i] = intaps[i];
00095         Ataps[i] = outtaps[i];
00096   }
00097 }
00098 
00099 template<class iType,class oType> 
00100 void VrIIRfilter<iType,oType>::initialize()
00101 {
00102   //setOutputHistory(order);
00103   //setHistory(order);
00104 }
00105 
00106 template<class iType,class oType> 
00107 VrIIRfilter<iType,oType>::~VrIIRfilter()
00108 {
00109   delete Ataps;
00110   delete Btaps;
00111   delete input_hist;
00112   delete output_hist;
00113 }
00114 
00115 #endif
00116 
00117 
00118 
00119 
00120 
00121 
00122 
00123 

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