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/* -*- c++ -*- */
/*
* Copyright 2015 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_FEC_POLAR_DECODER_SC_SYSTEMATIC_H
#define INCLUDED_FEC_POLAR_DECODER_SC_SYSTEMATIC_H
#include <gnuradio/fec/api.h>
#include <gnuradio/fec/polar_decoder_common.h>
namespace gr {
namespace fec {
namespace code {
/*!
* \brief Standard systematic successive cancellation (SC) decoder for POLAR codes
*
* \details
* It expects float input with bits mapped 1 --> 1, 0 --> -1
* Or: f = 2.0 * bit - 1.0
*
* Systematic encoding indicates that the info bit values are present in the codeword.
* 'info_bit_positions' may be obtained by ordering all non frozen_bit_positions in increasing order.
* One may extract them at their positions after a bit reversal operation.
* encoder -> decoder chain would need additional bit-reversal after encoding + before decoding.
* This is unnecessary.
*/
class FEC_API polar_decoder_sc_systematic : public polar_decoder_common
{
public:
/*!
* \param block_size codeword size. MUST be a power of 2.
* \param num_info_bits represents the number of information
* bits in a block. Also called frame_size. <= block_size
* \param frozen_bit_positions is an integer vector which
* defines the position of all frozen bits in a block.
* Its size MUST be equal to block_size - num_info_bits.
* Also it must be sorted and every position must only
* occur once.
*/
static generic_decoder::sptr make(int block_size, int num_info_bits,
std::vector<int> frozen_bit_positions);
~polar_decoder_sc_systematic();
// FECAPI
void generic_work(void *in_buffer, void *out_buffer);
private:
polar_decoder_sc_systematic(int block_size, int num_info_bits, std::vector<int> frozen_bit_positions);
float* d_llr_vec;
unsigned char* d_u_hat_vec;
unsigned char* d_frame_vec;
unsigned char retrieve_bit_from_llr(float llr, const int pos);
void sc_decode(float* llrs, unsigned char* u);
void extract_info_bits_reversed(unsigned char* outbuf, const unsigned char* inbuf);
};
} /* namespace code */
} // namespace fec
} // namespace gr
#endif /* INCLUDED_FEC_POLAR_DECODER_SC_SYSTEMATIC_H */
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