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// Generate some example LDPC codes

#include <itpp/itcomm.h>

using namespace itpp;
using namespace std;

extern int main(int argc, char **argv)
{ 
  { // This generates a random regular (3,6) code with 500 bits
    cout << "========= RANDOM (3,6) CODE ==========" << endl;
    LDPC_Parity_Matrix H;
    H.generate_regular_ldpc(500,3,6,
                            "rand",  // random unstructured matrix
                            "500 10");   // optimize girth
    H.display_stats();
    LDPC_Code C1(H);
    C1.save_to_file("random_3_6_code.it"); 
  }

  { // This is the code "204.33.484 (N=204,K=102,M=102,R=0.5)" from
    // David MacKay's database over sparse-graph code.  It can be
    // obtained with "wget
    // http://www.inference.phy.cam.ac.uk/mackay/codes/EN/C/204.33.484"
    cout << "========= MACKAY CODE ==========" << endl;
    LDPC_Parity_Matrix H("204.33.484","alist");
    H.display_stats();
    LDPC_Generator_Matrix G(H);
    LDPC_Code C(H,G);
    C.save_to_file("mackay_204.33.484.it"); 

    // Now produce a girth-optimized version of this code by removing
    // cycles. This slightly improves the performance at high SNR.
    H.cycle_removal_MGW(12);
    LDPC_Generator_Matrix G1(H);
    LDPC_Code C1(H,G1);
    C1.save_to_file("mackay_204.33.484_opt.it"); 
  }
    
  // Irregular 1/2-rate codes optimized for the AWGN channel. The
  // degree distributions are taken from Richardson & Urbanke,
  // Trans. IT 2001.  

  { // 1000 bits
    cout << "========= IRREGULAR CODE 1000 BITS ==========" << endl;
    LDPC_Parity_Matrix H;
    H.generate_irregular_ldpc(1000,
                              "0 0.27684 0.28342 0 0 0 0 0 0.43974",
                              "0 0 0 0 0 0.01568 0.85244 0.13188",
                              "rand",   // random unstructured matrix
                              "500 8"); // optimize girth
    LDPC_Code C(H);
    C.save_to_file("RU_1000.it"); 
  }

  {  // 10000 bits (takes a few minutes to run)
    cout << "========= IRREGULAR CODE 10000 BITS ==========" << endl;
    LDPC_Parity_Matrix H;
    H.generate_irregular_ldpc(10000,"0 0.21991 0.23328 0.02058 0 0.08543 0.06540 0.04767 \
                              0.01912 0 0 0 0 0 0 0 0 0 0.08064 0.22798", 
                              "0 0 0 0 0 0 0 0.64854 0.34747 0.00399",
                              "rand",  // random unstructured matrix
                              "150 8"); // optimize
    LDPC_Code C(H);
    C.save_to_file("RU_10000.it"); 
  }

  { // 100000 bits (takes a while to run)
    cout << "========= IRREGULAR CODE 100000 BITS ==========" << endl;
    LDPC_Parity_Matrix H;
    H.generate_irregular_ldpc(100000,"0 0.1712 0.21053 0.00273 0 0 0.00009 0.15269 0.09227 \
                              0.02802 0 0 0 0 0.01206 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.07212 0 0 0 0 \
                              0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.25830",
                              "0 0 0 0 0 0 0 0 0.33620 0.08883 0.57497",
                              "rand",  
                              "40 4");  // less aggressive optimization
    LDPC_Code C(H);
    C.save_to_file("RU_100000.it"); 
  }
    
  exit(0);
  
  { // 1000000 bits (THIS CODE REQUIRES ABOUT 450 MB TO STORE AND 2GB
    // INTERNAL MEMORY TO GENERATE)
    cout << "========= IRREGULAR CODE 1000000 BITS ==========" << endl;
    LDPC_Parity_Matrix H;
    H.generate_irregular_ldpc(1000000,"0 0.1712 0.21053 0.00273 0 0 0.00009 0.15269 0.09227 \
                              0.02802 0 0 0 0 0.01206 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.07212 0 0 0 0 \
                              0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.25830",
                              "0 0 0 0 0 0 0 0 0.33620 0.08883 0.57497",
                              "rand",
                              "0 0");  // no optimization here
    LDPC_Code C(H);
    C.save_to_file("RU_1000000.it"); 
  }
    
}
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