2 * 11/19/04 : 1.0 moved to LGPL.
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4 * 02/12/99 : Java Conversion by E.B , javalayer@javazoom.net
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6 * @(#) crc.h 1.5, last edit: 6/15/94 16:55:32
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7 * @(#) Copyright (C) 1993, 1994 Tobias Bading (bading@cs.tu-berlin.de)
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8 * @(#) Berlin University of Technology
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9 *-----------------------------------------------------------------------
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10 * This program is free software; you can redistribute it and/or modify
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11 * it under the terms of the GNU Library General Public License as published
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12 * by the Free Software Foundation; either version 2 of the License, or
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13 * (at your option) any later version.
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15 * This program is distributed in the hope that it will be useful,
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16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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18 * GNU Library General Public License for more details.
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20 * You should have received a copy of the GNU Library General Public
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21 * License along with this program; if not, write to the Free Software
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22 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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23 *----------------------------------------------------------------------
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27 * 16-Bit CRC checksum
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30 public final class Crc16 {
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31 private static short polynomial = (short) 0x8005;
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38 crc = (short) 0xFFFF;
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42 * Feed a bitstring to the crc calculation (0 < length <= 32).
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46 public void add_bits(int bitstring, int length) {
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47 int bitmask = 1 << (length - 1);
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49 if (((crc & 0x8000) == 0) ^ ((bitstring & bitmask) == 0)) {
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55 } while ((bitmask >>>= 1) != 0);
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59 * Return the calculated checksum. Erase it for next calls to add_bits().
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62 public short checksum() {
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64 crc = (short) 0xFFFF;
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