polar_encoder.h

Go to the documentation of this file.

/* -*- 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_ENCODER_H
#define INCLUDED_FEC_POLAR_ENCODER_H

#include <gnuradio/fec/api.h>
#include <gnuradio/fec/generic_encoder.h>
#include <gnuradio/fec/polar_common.h>

namespace gr {
namespace fec {
namespace code {

/*!
 * \brief POLAR encoder
 * for basic details see 'polar_common' class.
 * \ingroup error_coding_blk
 *
 * \details
 * expects values with MSB first. It needs a full information word and encodes it in one
 * pass. Output is a codeword of block_size.
 */
class FEC_API polar_encoder : public generic_encoder, public polar_common
{
public:
    /*!
     * Factory for a polar code encoder object.
     *
     * \param block_size defines the codeword size. It MUST be a
     *        power of 2.
     * \param num_info_bits represents the number of information
     *        bits in a block. Also called frame_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.
     * \param frozen_bit_values holds an unpacked byte for every
     *        frozen bit position. It defines if a frozen bit is
     *        fixed to '0' or '1'. Defaults to all ZERO.
     * \param is_packed choose 1 active bit/byte or 8 active
     *        bit/byte. if false, VOLK polar encoder is used.
     */
    static generic_encoder::sptr make(int block_size,
                                      int num_info_bits,
                                      std::vector<int> frozen_bit_positions,
                                      std::vector<char> frozen_bit_values,
                                      bool is_packed = false);
    ~polar_encoder();

    // FECAPI
    void generic_work(void* in_buffer, void* out_buffer);
    double rate() { return (1.0 * get_input_size() / get_output_size()); };
    int get_input_size() { return num_info_bits() / (d_is_packed ? 8 : 1); };
    int get_output_size() { return block_size() / (d_is_packed ? 8 : 1); };
    bool set_frame_size(unsigned int frame_size) { return false; };
    const char* get_input_conversion() { return d_is_packed ? "pack" : "none"; };
    const char* get_output_conversion() { return d_is_packed ? "packed_bits" : "none"; };

private:
    polar_encoder(int block_size,
                  int num_info_bits,
                  std::vector<int>& frozen_bit_positions,
                  std::vector<char>& frozen_bit_values,
                  bool is_packed);
    bool d_is_packed;

    // c'tor method for packed algorithm setup.
    void setup_frozen_bit_inserter();

    // methods insert input bits and frozen bits into packed array for encoding
    unsigned char* d_frozen_bit_prototype; // packed frozen bits are written onto it and
                                           // later copies are used.
    void insert_packed_frozen_bits_and_reverse(unsigned char* target,
                                               const unsigned char* input) const;
    void insert_unpacked_bit_into_packed_array_at_position(unsigned char* target,
                                                           const unsigned char bit,
                                                           const int pos) const;
    void insert_packet_bit_into_packed_array_at_position(unsigned char* target,
                                                         const unsigned char bit,
                                                         const int target_pos,
                                                         const int bit_pos) const;

    // packed encoding methods
    void encode_vector_packed(unsigned char* target) const;
    void encode_vector_packed_subbyte(unsigned char* target) const;
    void encode_packed_byte(unsigned char* target) const;
    void encode_vector_packed_interbyte(unsigned char* target) const;
};

} // namespace code
} // namespace fec
} // namespace gr

#endif /* INCLUDED_FEC_POLAR_ENCODER_H */