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GrInterpolator.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 
00023 #ifndef _GRINTERPOLATOR_H_
00024 #define _GRINTERPOLATOR_H_
00025 
00026 #include <GrFractionalInterpolatingSigProc.h>
00027 #include <stdlib.h>
00028 #include <gr_mmse_fir_interpolator.h>
00029 
00038 template<class iType, class oType>
00039 class GrInterpolator : public GrFractionalInterpolatingSigProc<iType,oType>
00040 {
00041  public:
00043   GrInterpolator (int N, int M, int phase = 0);
00044   ~GrInterpolator () {};
00045 
00046   const char *name () { return "GrInterpolator"; }
00047   int work (VrSampleRange output, void *ao[], VrSampleRange inputs[], void *ai[]);
00048 
00049 protected:
00050   int                           phase;
00051   gr_mmse_fir_interpolator      intr;
00052 };
00053 
00054 template<class iType,class oType>
00055 GrInterpolator<iType,oType>::GrInterpolator (int N, int M, int _phase = 0)
00056   : GrFractionalInterpolatingSigProc<iType,oType>(N, M), phase (_phase)
00057 {
00058   if (N != 10){
00059     cerr << "GrInterpolator: N must be 10\n";
00060     exit (1);
00061   }
00062   if (M < 0 || M > 10){
00063     cerr << "GrInterpolator: M must be in [1, 10]\n";
00064     exit (1);
00065   }
00066   if (phase < 0 || phase > N){
00067     cerr << "GrInterpolator: phase must be in [0, N]\n";
00068     exit (1);
00069   }
00070 
00071   history = intr.ntaps () + 1;
00072 }
00073 
00074 template<class iType,class oType>
00075 int
00076 GrInterpolator<iType,oType>::work (VrSampleRange output, void *ao[],
00077                                    VrSampleRange inputs[], void *ai[])
00078 {
00079   iType *in =  ((iType **) ai)[0];
00080   oType *out = ((oType **) ao)[0];
00081 
00082   assert ((output.size % iratio) == 0);
00083 
00084   float mu = (float) phase / N;                 // fractional delay
00085   float mu_inc = (float) M / N;
00086 
00087   unsigned      ii = 0;                         // input index
00088   unsigned      oo = 0;                         // output index
00089 
00090   while (oo < output.size){
00091     out[oo++] = intr.interpolate (&in[ii], 1.0 - mu);
00092 
00093     // printf ("%4d %9.6f\n", ii, mu);
00094 
00095     float s = mu + mu_inc;
00096     float f = floor (s);
00097     int incr = (int) f;
00098     mu = s - f;
00099     ii += incr;
00100   }
00101 
00102   assert (mu == ((float) phase / N));
00103 
00104   return output.size;
00105 }
00106 
00107 
00108 #endif /* _GRINTERPOLATOR_H_ */

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