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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_IMPL_H
#define INCLUDED_GR_SIMPLE_CORRELATOR_IMPL_H
#include <gnuradio/digital/simple_correlator.h>
//#define DEBUG_SIMPLE_CORRELATOR
namespace gr {
namespace digital {
class simple_correlator_impl : public simple_correlator
{
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
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:
simple_correlator_impl(int payload_bytesize);
~simple_correlator_impl();
int general_work(int noutput_items,
gr_vector_int &ninput_items,
gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items);
};
} /* namespace digital */
} /* namespace gr */
#endif /* INCLUDED_GR_SIMPLE_CORRELATOR_IMPL_H */
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