GNU Radio 3.5.3.2 C++ API
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00001 /* -*- c++ -*- */ 00002 /* 00003 * Copyright 2004 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 3, 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., 51 Franklin Street, 00020 * Boston, MA 02110-1301, USA. 00021 */ 00022 00023 #ifndef INCLUDED_GR_SIMPLE_CORRELATOR_H 00024 #define INCLUDED_GR_SIMPLE_CORRELATOR_H 00025 00026 #include <gr_core_api.h> 00027 #include <gr_block.h> 00028 #include <assert.h> 00029 00030 //#define DEBUG_SIMPLE_CORRELATOR 00031 00032 class gr_simple_correlator; 00033 typedef boost::shared_ptr<gr_simple_correlator> gr_simple_correlator_sptr; 00034 00035 GR_CORE_API gr_simple_correlator_sptr gr_make_simple_correlator (int payload_bytesize); 00036 00037 /*! 00038 * \brief inverse of gr_simple_framer (more or less) 00039 * \ingroup sync_blk 00040 */ 00041 class GR_CORE_API gr_simple_correlator : public gr_block 00042 { 00043 static const int OVERSAMPLE = 8; 00044 enum state_t { ST_LOOKING, ST_UNDER_THRESHOLD, ST_LOCKED }; 00045 00046 int d_payload_bytesize; 00047 state_t d_state; 00048 unsigned int d_osi; // over sample index [0,OVERSAMPLE-1] 00049 unsigned int d_transition_osi; // first index where Hamming dist < thresh 00050 unsigned int d_center_osi; // center of bit 00051 unsigned long long int d_shift_reg[OVERSAMPLE]; 00052 int d_bblen; // length of bitbuf 00053 unsigned char *d_bitbuf; // demodulated bits 00054 unsigned char *d_pktbuf; // temp packet buf 00055 int d_bbi; // bitbuf index 00056 00057 static const int AVG_PERIOD = 512; // must be power of 2 (for freq offset correction) 00058 int d_avbi; 00059 float d_avgbuf[AVG_PERIOD]; 00060 float d_avg; 00061 float d_accum; 00062 00063 #ifdef DEBUG_SIMPLE_CORRELATOR 00064 FILE *d_debug_fp; // binary log file 00065 #endif 00066 00067 friend GR_CORE_API gr_simple_correlator_sptr gr_make_simple_correlator (int payload_bytesize); 00068 gr_simple_correlator (int payload_bytesize); 00069 00070 00071 inline int slice (float x) 00072 { 00073 return x >= d_avg ? 1 : 0; 00074 } 00075 00076 void update_avg(float x); 00077 00078 void enter_locked (); 00079 void enter_under_threshold (); 00080 void enter_looking (); 00081 00082 static int add_index (int a, int b) 00083 { 00084 int t = a + b; 00085 if (t >= OVERSAMPLE) 00086 t -= OVERSAMPLE; 00087 assert (t >= 0 && t < OVERSAMPLE); 00088 return t; 00089 } 00090 00091 static int sub_index (int a, int b) 00092 { 00093 int t = a - b; 00094 if (t < 0) 00095 t += OVERSAMPLE; 00096 assert (t >= 0 && t < OVERSAMPLE); 00097 return t; 00098 } 00099 00100 00101 public: 00102 ~gr_simple_correlator (); 00103 00104 int general_work (int noutput_items, 00105 gr_vector_int &ninput_items, 00106 gr_vector_const_void_star &input_items, 00107 gr_vector_void_star &output_items); 00108 }; 00109 00110 00111 #endif /* INCLUDED_GR_SIMPLE_CORRELATOR_H */