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/* -*- c++ -*- */
/*
* Reed-Solomon decoder for DAB+
* Copyright 2002 Phil Karn, KA9Q
* May be used under the terms of the GNU General Public License (GPL)
*
* Rewritten into a GNU Radio block for gr-dab
* Copyright 2017 Moritz Luca Schmid, Communications Engineering Lab (CEL) / Karlsruhe Institute of Technology (KIT).
*
* 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 <stdexcept>
#include <stdio.h>
#include <sstream>
#include <boost/format.hpp>
#include <gnuradio/io_signature.h>
#include "reed_solomon_decode_bb_impl.h"
using namespace boost;
namespace gr {
namespace dab {
reed_solomon_decode_bb::sptr
reed_solomon_decode_bb::make(int bit_rate_n)
{
return gnuradio::get_initial_sptr
(new reed_solomon_decode_bb_impl(bit_rate_n));
}
/*
* The private constructor
*/
reed_solomon_decode_bb_impl::reed_solomon_decode_bb_impl(int bit_rate_n)
: gr::block("reed_solomon_decode_bb",
gr::io_signature::make(1, 1, sizeof(unsigned char)),
gr::io_signature::make(1, 1, sizeof(unsigned char))),
d_bit_rate_n(bit_rate_n)
{
rs_handle = init_rs_char(8, 0x11D, 0, 1, 10, 135);
if (!rs_handle) {
GR_LOG_DEBUG(d_logger, "RS init failed");
} else {
GR_LOG_DEBUG(d_logger, "RS init succeeded");
}
d_superframe_size = bit_rate_n * 120;
d_superframe_size_rs = bit_rate_n * 110;
set_output_multiple(d_superframe_size_rs);
d_corrected_errors = 0;
}
/*
* Our virtual destructor.
*/
reed_solomon_decode_bb_impl::~reed_solomon_decode_bb_impl()
{
free_rs_char(rs_handle);
}
void reed_solomon_decode_bb_impl::DecodeSuperframe(uint8_t *sf, size_t sf_len)
{
// // insert errors for test
// sf[0] ^= 0xFF;
// sf[10] ^= 0xFF;
// sf[20] ^= 0xFF;
int subch_index = sf_len / 120;
int total_corr_count = 0;
bool uncorr_errors = false;
// process all RS packets
for (int i = 0; i < subch_index; i++) {
for (int pos = 0; pos < 120; pos++) {
rs_packet[pos] = sf[pos * subch_index + i];
}
// detect errors
int corr_count = decode_rs_char(rs_handle, rs_packet, corr_pos, 0);
if (corr_count == -1) {
uncorr_errors = true;
GR_LOG_DEBUG(d_logger, "uncorrectable error");
} else
total_corr_count += corr_count;
// correct errors
for (int j = 0; j < corr_count; j++) {
int pos = corr_pos[j] - 135;
if (pos < 0)
continue;
sf[pos * subch_index + i] = rs_packet[pos];
}
}
//GR_LOG_DEBUG(d_logger, format("RS corrected %d errors in superframe") % total_corr_count);
d_corrected_errors = total_corr_count;
}
void
reed_solomon_decode_bb_impl::forecast(int noutput_items, gr_vector_int &ninput_items_required)
{
ninput_items_required[0] = noutput_items*120/110;
}
int
reed_solomon_decode_bb_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];
for (int n = 0; n < noutput_items / d_superframe_size_rs; n++) {
uint8_t superframe[d_superframe_size];
memcpy(superframe, &in[n * d_superframe_size], d_superframe_size);
DecodeSuperframe(superframe, d_superframe_size);
memcpy(&out[n * d_superframe_size_rs], superframe, d_superframe_size_rs);
}
// Tell runtime system how many input items we consumed on
// each input stream.
consume_each(noutput_items * 120 / 110);
// Tell runtime system how many output items we produced.
return noutput_items;
}
} /* namespace dab */
} /* namespace gr */
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