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/* -*- c++ -*- */
/*
* Copyright 2002 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 <atsci_basic_trellis_encoder.h>
#include <assert.h>
const unsigned char atsci_basic_trellis_encoder::next_state[32] = {
0,1,4,5,
2,3,6,7,
1,0,5,4,
3,2,7,6,
4,5,0,1,
6,7,2,3,
5,4,1,0,
7,6,3,2
};
const unsigned char atsci_basic_trellis_encoder::out_symbol[32] = {
0,2,4,6,
1,3,5,7,
0,2,4,6,
1,3,5,7,
4,6,0,2,
5,7,1,3,
4,6,0,2,
5,7,1,3
};
/*!
* Encode two bit INPUT into 3 bit return value. Domain is [0,3],
* Range is [0,7]. The mapping to bipolar levels is not done.
*/
int
atsci_basic_trellis_encoder::encode (unsigned int input)
{
assert (input < 4);
int index = (state << 2) + input;
state = next_state[index];
return out_symbol[index];
}
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