lib/fec/ldpc/alist.h

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/*!
 * \file
 * \brief Definition of a class to hold sparse matrices in alist-format
 * \author Manu T S
 *
 * -----------------------------------------------------------------
 *
 * Copyright 2013 IIT Bombay.
 * 
 * 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.
 *
 * -----------------------------------------------------------------
 *
 * This class handles sparse matrices specified in alist-format.
 * For details about alist format please visit the link below.
 * - http://www.inference.phy.cam.ac.uk/mackay/codes/alist.html
 *
 * Alist class is an efficient way of representing a sparse matrix
 * the parity check matrix H of an LDPC code for instance.
 *
 */

#ifndef ALIST_H
#define ALIST_H

#include <iostream>
#include <fstream>
#include <sstream>
#include <vector>
#include <stdlib.h>

class alist
{
  public:

    //! Default Constructor
    alist() : data_ok(false) {}

    //! Constructor which loads alist class from an alist-file
    alist(const char * fname);

    //! Read alist data from a file
    void read(const char * fname);

    //! Write alist data to a file
    void write(const char * fname) const;

    //! Retuns N, the number of variable nodes
    int get_N();

    //! Return M, the number of check nodes
    int get_M();

    //! Return the m_list variable
    std::vector< std::vector<int> > get_mlist();

    //! Returns the n_list variable
    std::vector< std::vector<int> > get_nlist();

    //! Returns the num_mlist variable
    std::vector<int> get_num_mlist();

    //! Returns the num_nlist variable
    std::vector<int> get_num_nlist();

    //! Returns the max_num_nlist variable
    int get_max_num_nlist();

    //! Returns the max_num_mlist variable
    int get_max_num_mlist();

    //! Prints the nlist[i] variable
    void print_nlist_i(int i);

    //! Prints the mlist[i] variable
    void print_mlist_i(int i);

    //! Returns the corresponding H matrix
    std::vector<std::vector<char> > get_matrix();

  protected:
    //! A variable indicating if data has been read from alist-file
    bool data_ok;

    //! Number of variable nodes
    int N;

    //! Number of check nodes
    int M;

    //! Maximum weight of rows
    int max_num_mlist;

    //! Maximum weight of columns
    int max_num_nlist;

    //! Weight of each column n
    std::vector<int> num_nlist;

    //! Weight of each row m
    std::vector<int> num_mlist;

    //! List of integer coordinates along each rows with non-zero entries
    std::vector< std::vector<int> > mlist;

    //! List of integer coordinates along each column with non-zero entries
    std::vector< std::vector<int> > nlist;
};
#endif // ifndef ALIST_H