modem/LDPC1.cpp

// Copyright 2011-2013, Nima Najari Moghadam and Per Zetterberg
//                      KTH Royal Institute of Technology
// 
//
// This program 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 of the License, or
// (at your option) any later version.
//
// This program 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 program.  If not, see <http://www.gnu.org/licenses/>.
//

#include <itpp/itcomm.h>
#include "LDPC1.hpp"




void LDPC1::init(double chan_code_rate, int word_size, int seed, bool load_from_file, string filename) {

   // Use chan_code_rates: 1/4, 1/2, 3/4, 5/6

    d_chan_code_rate=chan_code_rate;
    d_seed=seed;

    //Nvar = int(msg_len'gth/chan_code_rate);
    
    Nvar=word_size;
    k=int(Nvar*chan_code_rate);
   

    //std::cout << "Nvar=" << Nvar << endl;
    int Wc = 3;
    int Wr = int(Wc/(1-chan_code_rate));

    //std::cout << "R=" << 1-((float) Wc)/((float) Wr) << std::endl;
    //std::cout << "Wr=" << Wr << std::endl;
    //std::cout << "word_size=" << word_size << endl;

    //R=1-(Wc/Wr)  <==>  (Wc/Wr)=1-R <==>  Wr/Wc=1/(1-R) <==> Wr = Wc/(1-R)


    if (load_from_file) {
      Code.load_code(filename.c_str(),&G);
    }
    else
    {
      std::cout << "Generate code start \n";
      RNG_reset(d_seed);                
      H.generate(Nvar, Wc, Wr,"rand","500 10");
      G.construct(&H);
      std::cout << "Generate code stop \n";
      Code.set_code(&H,&G);
      Code.set_exit_conditions(10);
      Code.save_code(filename.c_str());
    };
   
        
    RNG_reset(d_seed);          
    d_interleaver.set_interleaver_depth(Nvar);
    d_interleaver.randomize_interleaver_sequence();

    ivec s=d_interleaver.get_interleaver_sequence();

    code_word1.set_length(Nvar);
    code_word2.set_length(Nvar);


}


void LDPC1::chan_encode(bvec message, bvec &code_word)  {
  
  Code.encode(message,code_word);
  code_word1=to_vec(code_word);
  d_interleaver.interleave(code_word1,code_word2);
  code_word=to_bvec(code_word2);

}

void LDPC1::chan_decode(vec &soft_input,bvec &message_hat){
 
  bvec message_hat_temp;

  message_hat_temp.set_length(k);
  d_interleaver.deinterleave(soft_input,code_word1);
  Code.decode(code_word1,message_hat_temp);
  message_hat.set_subvector(0,message_hat_temp);


};