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/* -*- c++ -*- */
/*
* Copyright 2004,2013 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* GNU Radio is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3, or (at your option)
* any later version.
*
* GNU Radio is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU Radio; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#ifndef INCLUDED_GR_SIMPLE_CORRELATOR_H
#define INCLUDED_GR_SIMPLE_CORRELATOR_H
#include <digital_api.h>
#include <gr_block.h>
class digital_simple_correlator;
typedef boost::shared_ptr<digital_simple_correlator> digital_simple_correlator_sptr;
DIGITAL_API digital_simple_correlator_sptr digital_make_simple_correlator(int payload_bytesize);
/*!
* \brief inverse of simple_framer (more or less)
* \ingroup sync_blk
*/
class DIGITAL_API digital_simple_correlator : public gr_block
{
private:
static const int OVERSAMPLE = 8;
enum state_t { ST_LOOKING, ST_UNDER_THRESHOLD, ST_LOCKED };
int d_payload_bytesize;
state_t d_state;
unsigned int d_osi; // over sample index [0,OVERSAMPLE-1]
unsigned int d_transition_osi; // first index where Hamming dist < thresh
unsigned int d_center_osi; // center of bit
unsigned long long int d_shift_reg[OVERSAMPLE];
int d_bblen; // length of bitbuf
unsigned char *d_bitbuf; // demodulated bits
unsigned char *d_pktbuf; // temp packet buf
int d_bbi; // bitbuf index
static const int AVG_PERIOD = 512; // must be power of 2 (for freq offset correction)
int d_avbi;
float d_avgbuf[AVG_PERIOD];
float d_avg;
float d_accum;
#ifdef DEBUG_SIMPLE_CORRELATOR
FILE *d_debug_fp; // binary log file
#endif
friend GR_CORE_API digital_simple_correlator_sptr
digital_make_simple_correlator(int payload_bytesize);
digital_simple_correlator(int payload_bytesize);
inline int slice(float x)
{
return x >= d_avg ? 1 : 0;
}
void update_avg(float x);
void enter_locked();
void enter_under_threshold();
void enter_looking();
static int add_index(int a, int b)
{
int t = a + b;
if(t >= OVERSAMPLE)
t -= OVERSAMPLE;
assert(t >= 0 && t < OVERSAMPLE);
return t;
}
static int sub_index(int a, int b)
{
int t = a - b;
if(t < 0)
t += OVERSAMPLE;
assert(t >= 0 && t < OVERSAMPLE);
return t;
}
public:
~digital_simple_correlator();
int general_work(int noutput_items,
gr_vector_int &ninput_items,
gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items);
};
#endif /* INCLUDED_GR_SIMPLE_CORRELATOR_H */
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