66 lines
2.1 KiB
Java
66 lines
2.1 KiB
Java
/*
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* Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package sun.misc;
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/**
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* The CRC-16 class calculates a 16 bit cyclic redundancy check of a set
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* of bytes. This error detecting code is used to determine if bit rot
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* has occurred in a byte stream.
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*/
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public class CRC16 {
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/** value contains the currently computed CRC, set it to 0 initally */
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public int value;
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public CRC16() {
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value = 0;
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}
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/** update CRC with byte b */
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public void update(byte aByte) {
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int a, b;
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a = (int) aByte;
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for (int count = 7; count >=0; count--) {
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a = a << 1;
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b = (a >>> 8) & 1;
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if ((value & 0x8000) != 0) {
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value = ((value << 1) + b) ^ 0x1021;
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} else {
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value = (value << 1) + b;
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}
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}
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value = value & 0xffff;
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return;
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}
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/** reset CRC value to 0 */
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public void reset() {
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value = 0;
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}
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}
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