LDPC example

// only need 112 bit for 14 ascii character
        LDPC_Parity_Irregular H;
        H.generate(224,
                   "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_Generator_Systematic G(&H);
        LDPC_Code C(&H, &G);
        C.set_exit_conditions(2500);
//        C.set_llrcalc(LLR_calc_unit(12,0,7));
        NSLog(@"code generated completed\n");
        {
            bvec InData = zeros_b(112);
            NSLog(@"%i",InData.length());
    //        NSString *input = @"ab123456789012";
            char input[] = "ab123987564912";
            for(int i = 0; i < 14; i++) {
                char c = input[i];
                for(int bitIndex = 0; bitIndex < 8; bitIndex++) {
                    InData.set(i*8+bitIndex, bin((c >> abs(bitIndex-7)) & 1));
                }
            }
            bvec outData = C.encode(InData);
    //        G.encode(InData,outData);
//            cout << InData << endl;
//            cout << outData << endl;
            
            BPSK Mod;
            vec s = Mod.modulate_bits(outData);
            // create noise
            vec EbN0db = "0.6:0.2:5";
            QLLRvec llr;
            for(int n = 0; n < length(EbN0db); n++) {
                double N0 = pow(10.0, -EbN0db(1) / 10.0) / C.get_rate();
                NSLog(@"error rate %f",N0);
                AWGN_Channel chan(N0 / 2);
                vec x = chan(s);
                vec softbits = Mod.demodulate_soft_bits(x, N0);
                // Decode the received bits
//                llr = C.get_llrcalc().to_qllr(softbits);
                int it = C.bp_decode(C.get_llrcalc().to_qllr(softbits), llr);
                if(it >= 0) {
                    NSLog(@"used %i iteration on %i",it,n);
                    break;
                } else {
                    llr.clear();
                }
                NSLog(@"used %i iteration on %i",it,n);
            }
            
            cout << llr.length() << endl;
            bvec answer = llr.get(0, 111) < 0;
            cout << answer << endl;
            char *final = (char*)calloc(14,sizeof(char));
            for(int i = 0; i < 14; i++) {
                for(int bitIndex = 0; bitIndex < 8; bitIndex++) {
                    bin b = answer.get(i*8+bitIndex);
                    if(b == 1) {
                        final[i] |= 1 << abs(bitIndex-7);
                    }
                }
            }
            cout << final << endl;
        }