gr-fec/include/gnuradio/fec/viterbi.h

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/*
 * Copyright 2008,2018 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.
 */

/* The path memory for each state is 32 bits. This is slightly shorter
 * than we'd like for K=7, especially since we chain back every 8 bits.
 * But it fits so nicely into a 32-bit machine word...
 */

#ifndef INCLUDED_VITERBI_H
#define INCLUDED_VITERBI_H

#include <gnuradio/fec/api.h>

namespace gr {
namespace fec {

struct FEC_API viterbi_state {
    unsigned long path; /* Decoded path to this state */
    long metric;        /* Cumulative metric to this state */
};

FEC_API
void gen_met(int mettab[2][256], /* Metric table */
             int amp,            /* Signal amplitude */
             double esn0,        /* Es/N0 ratio in dB */
             double bias,        /* Metric bias */
             int scale);         /* Scale factor */

FEC_API unsigned char encode(unsigned char* symbols,
                             unsigned char* data,
                             unsigned int nbytes,
                             unsigned char encstate);

FEC_API void viterbi_chunks_init(struct viterbi_state* state);

FEC_API void viterbi_butterfly2(unsigned char* symbols,
                                int mettab[2][256],
                                struct viterbi_state* state0,
                                struct viterbi_state* state1);

FEC_API unsigned char viterbi_get_output(struct viterbi_state* state,
                                         unsigned char* outbuf);
} // namespace fec
} // namespace gr

#endif /* INCLUDED_VITERBI_H */