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GrFractionalInterpolatingSigProc.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 _GRFRACTIONALINTERPOLATINGSIGPROC_H_ 00024 #define _GRFRACTIONALINTERPOLATINGSIGPROC_H_ 00025 00026 #include <VrHistoryProc.h> 00027 #include <stdlib.h> 00028 #include <gr_math.h> 00029 #include <gr_mmse_fir_interpolator.h> 00030 00035 template<class iType, class oType> 00036 class GrFractionalInterpolatingSigProc : public VrHistoryProc<iType,oType> 00037 { 00038 public: 00039 GrFractionalInterpolatingSigProc (int outputs, int arg_N, int arg_M) 00040 : VrHistoryProc<iType,oType>(outputs), N(arg_N), M(arg_M) {} 00041 00042 GrFractionalInterpolatingSigProc (int arg_N, int arg_M) 00043 : VrHistoryProc<iType,oType>(1), N(arg_N), M(arg_M) {} 00044 00045 ~GrFractionalInterpolatingSigProc () {}; 00046 00047 void pre_initialize (); 00048 int forecast (VrSampleRange output, VrSampleRange inputs[]); 00049 00050 protected: 00051 int N; // numerator of ratio 00052 int M; // denominator of ratio 00053 int iratio; // smallest integer multiple of N/M 00054 }; 00055 00056 template<class iType,class oType> int 00057 GrFractionalInterpolatingSigProc<iType,oType>::forecast(VrSampleRange output, 00058 VrSampleRange inputs[]) { 00059 /* 1:iratio ratio */ 00060 /* 00061 * Note that this code only works correctly if output size of the 00062 * module (set using setOutputSize(n) in pre_initialize() ) is a multiple 00063 * of iratio. 00064 */ 00065 assert ((output.size % iratio) == 0); 00066 00067 for(unsigned int i=0;i<numberInputs;i++) { 00068 inputs[i].index=output.index/iratio; /* ! do not subtract history ! */ 00069 inputs[i].size=output.size/iratio + history-1; 00070 } 00071 return 0; 00072 } 00073 00074 00075 template<class iType,class oType> void 00076 GrFractionalInterpolatingSigProc<iType,oType>::pre_initialize () 00077 { 00078 if (getSamplingFrequency () == 0.0) 00079 setSamplingFrequency ((getInputSamplingFrequencyN (0) * N) / M); 00080 00081 // reduce N/M to lowest terms and then use N*M as the size 00082 00083 int d = gr_gcd (N, M); 00084 iratio = (N * M) / (d * d); 00085 00086 setOutputSize(iratio); 00087 } 00088 00089 #endif /* _GRFRACTIONALINTERPOLATINGSIGPROC_H_ */

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