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/* ====================================================================
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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==================================================================== */
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/* ================================================================
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* About NPOI
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* Author: Tony Qu
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* Author's email: tonyqus (at) gmail.com
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* Author's Blog: tonyqus.wordpress.com.cn (wp.tonyqus.cn)
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* HomePage: http://www.codeplex.com/npoi
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* Contributors:
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*
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* ==============================================================*/
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using System;
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using System.Collections.Generic;
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using System.Text;
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namespace HH.WMS.Utils.NPOI.Util
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{
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using System;
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using System.IO;
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/// <summary>
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/// CRC Verification
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/// </summary>
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public class CRC32
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{
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protected ulong[] crc32Table;
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/// <summary>
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/// Initializes a new instance of the <see cref="CRC32"/> class.
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/// </summary>
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public CRC32()
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{
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const ulong ulPolynomial = 0xEDB88320;
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ulong dwCrc;
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crc32Table = new ulong[256];
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int i, j;
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for (i = 0; i < 256; i++)
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{
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dwCrc = (ulong)i;
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for (j = 8; j > 0; j--)
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{
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if ((dwCrc & 1) == 1)
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dwCrc = (dwCrc >> 1) ^ ulPolynomial;
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else
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dwCrc >>= 1;
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}
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crc32Table[i] = dwCrc;
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}
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}
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/// <summary>
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/// CRC Bytes.
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/// </summary>
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/// <param name="buffer">The buffer.</param>
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/// <returns></returns>
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public ulong ByteCRC(ref byte[] buffer)
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{
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ulong ulCRC = 0xffffffff;
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ulong len;
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len = (ulong)buffer.Length;
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for (ulong buffptr = 0; buffptr < len; buffptr++)
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{
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ulong tabPtr = ulCRC & 0xFF;
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tabPtr = tabPtr ^ buffer[buffptr];
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ulCRC = ulCRC >> 8;
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ulCRC = ulCRC ^ crc32Table[tabPtr];
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}
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return ulCRC ^ 0xffffffff;
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}
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/// <summary>
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/// String CRC
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/// </summary>
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/// <param name="sInputString">the string</param>
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/// <returns></returns>
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public ulong StringCRC(string sInputString)
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{
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byte[] buffer = Encoding.Default.GetBytes(sInputString);
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return ByteCRC(ref buffer);
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}
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/// <summary>
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/// File CRC
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/// </summary>
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/// <param name="sInputFilename">the input file</param>
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/// <returns></returns>
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public long FileCRC(string sInputFilename)
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{
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using (FileStream inFile = new System.IO.FileStream(sInputFilename, System.IO.FileMode.Open, System.IO.FileAccess.Read))
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{
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byte[] bInput = new byte[inFile.Length];
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inFile.Read(bInput, 0, bInput.Length);
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return (long)ByteCRC(ref bInput);
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}
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}
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/// <summary>
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/// Stream CRC
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/// </summary>
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/// <param name="inFile">the input stream</param>
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/// <returns></returns>
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public long StreamCRC(Stream inFile)
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{
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try
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{
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byte[] bInput = new byte[inFile.Length];
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inFile.Read(bInput, 0, bInput.Length);
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inFile.Close();
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return (long)ByteCRC(ref bInput);
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}
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catch (IOException)
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{
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throw;
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}
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}
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}
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}
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