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/* -*- c++ -*- */
/*
* Copyright 2015,2016 Free Software Foundation, Inc.
*
* This 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.
*
* This software 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 this software; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <gnuradio/io_signature.h>
#include "dvbt_reed_solomon_dec_impl.h"
namespace gr {
namespace dtv {
static const int rs_init_symsize = 8;
static const int rs_init_fcr = 0; // first consecutive root
static const int rs_init_prim = 1; // primitive is 1 (alpha)
static const int N = (1 << rs_init_symsize) - 1; // 255
dvbt_reed_solomon_dec::sptr
dvbt_reed_solomon_dec::make(int p, int m, int gfpoly, int n, int k, int t, int s, int blocks)
{
return gnuradio::get_initial_sptr
(new dvbt_reed_solomon_dec_impl(p, m, gfpoly, n, k, t, s, blocks));
}
/*
* The private constructor
*/
dvbt_reed_solomon_dec_impl::dvbt_reed_solomon_dec_impl(int p, int m, int gfpoly, int n, int k, int t, int s, int blocks)
: block("dvbt_reed_solomon_dec",
io_signature::make(1, 1, sizeof(unsigned char) * blocks * (n - s)),
io_signature::make(1, 1, sizeof(unsigned char) * blocks * (k - s))),
d_n(n), d_k(k), d_s(s), d_blocks(blocks)
{
d_rs = init_rs_char(rs_init_symsize, gfpoly, rs_init_fcr, rs_init_prim, (n - k));
if (d_rs == NULL) {
GR_LOG_FATAL(d_logger, "Reed-Solomon Decoder, cannot allocate memory for d_rs.");
throw std::bad_alloc();
}
d_nerrors_corrected_count = 0;
d_bad_packet_count = 0;
d_total_packets = 0;
}
/*
* Our virtual destructor.
*/
dvbt_reed_solomon_dec_impl::~dvbt_reed_solomon_dec_impl()
{
free_rs_char(d_rs);
}
void
dvbt_reed_solomon_dec_impl::forecast (int noutput_items, gr_vector_int &ninput_items_required)
{
ninput_items_required[0] = noutput_items;
}
int
dvbt_reed_solomon_dec_impl::decode (unsigned char &out, const unsigned char &in)
{
unsigned char tmp[N];
int ncorrections;
// add missing prefix zero padding to message
memset(tmp, 0, d_s);
memcpy(&tmp[d_s], &in, (d_n - d_s));
// correct message...
ncorrections = decode_rs_char(d_rs, tmp, 0, 0);
// copy corrected message to output, skipping prefix zero padding
memcpy (&out, &tmp[d_s], (d_k - d_s));
return ncorrections;
}
int
dvbt_reed_solomon_dec_impl::general_work (int noutput_items,
gr_vector_int &ninput_items,
gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items)
{
const unsigned char *in = (const unsigned char *) input_items[0];
unsigned char *out = (unsigned char *) output_items[0];
int j = 0;
int k = 0;
for (int i = 0; i < (d_blocks * noutput_items); i++) {
int nerrors_corrected = decode(out[k], in[j]);
if (nerrors_corrected == -1) {
d_bad_packet_count++;
d_nerrors_corrected_count += ((d_n - d_s) - (d_k - d_s)) / 2; // lower bound estimate; most this RS can fix
}
else {
d_nerrors_corrected_count += nerrors_corrected;
}
d_total_packets++;
j += (d_n - d_s);
k += (d_k - d_s);
}
// Tell runtime system how many input items we consumed on
// each input stream.
consume_each (noutput_items);
// Tell runtime system how many output items we produced.
return noutput_items;
}
} /* namespace dtv */
} /* namespace gr */
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