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/*
* @(#) crc.cc 1.5, last edit: 15 Jun 1994 16:55:30
* @(#) Copyright (C) 1993, 1994 Tobias Bading (bading@cs.tu-berlin.de)
* @(#) Berlin University 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 2 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, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <iostream.h>
#include <stdlib.h>
#include "crc.h"
// generator polinomial:
const uint16 Crc16::polynomial = 0x8005;
void Crc16::add_bits (uint32 bitstring, uint32 length)
{
#ifdef DEBUG
if (!length)
{
cerr << "Length of bitstring has to be > 0 in Crc16::add_bits()!\n";
exit (1);
}
#endif
uint32 bitmask = 1 << (length - 1);
do
if (!(crc & 0x8000) ^ !(bitstring & bitmask))
{
crc <<= 1;
crc ^= polynomial;
}
else
crc <<= 1;
while (bitmask >>= 1);
}
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