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/* -*- 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.
*/
#include <gnuradio/fec/tpc_common.h>
namespace gr {
namespace fec {
int tpc_common::parity_counter(int symbol, int length)
{
int counter;
int temp_parity = 0;
for (counter = 0; counter < length; counter++) {
temp_parity = temp_parity ^ (symbol & 1);
symbol = symbol >> 1;
}
return (temp_parity);
}
void tpc_common::rsc_enc_bit(int input,
int state_in,
std::vector<int> g,
int KK,
int nn,
std::vector<std::vector<int>>& outputVec,
std::vector<std::vector<int>>& nextStateVec)
{
int state, i, out, a_k;
// systematic output
out = input;
// determine feedback bit
a_k = input ^ tpc_common::parity_counter(g[0] & state_in, KK);
// create a word made up of state and feedback bit
state = (a_k << (KK - 1)) ^ state_in;
// AND the word with the generators
for (i = 1; i < nn; i++) {
// update output symbol
out = (out << 1) + tpc_common::parity_counter(state & g[i], KK);
}
outputVec[input][state_in] = out;
nextStateVec[input][state_in] = (state >> 1);
}
void tpc_common::precomputeStateTransitionMatrix_RSCPoly(
int numStates,
std::vector<int> g,
int KK,
int nn,
std::vector<std::vector<int>>& output,
std::vector<std::vector<int>>& nextStates)
{
for (int input = 0; input < 2; input++) {
for (int state = 0; state < numStates; state++) {
tpc_common::rsc_enc_bit(input, state, g, KK, nn, output, nextStates);
}
}
}
void tpc_common::rsc_tail(std::vector<int>& tail_p,
std::vector<int> g,
int max_states,
int mm)
{
// Determine the tail for each state
for (int state = 0; state < max_states; state++) {
// determine feedback word
tail_p[state] = tpc_common::parity_counter(g[0] & state, mm);
}
return;
}
void tpc_common::itob(std::vector<int>& binVec, int symbol, int length)
{
/// Go through each bit in the vector
for (int counter = 0; counter < length; counter++) {
binVec[length - counter - 1] = (symbol & 1);
symbol = symbol >> 1;
}
}
} // namespace fec
} // namespace gr
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