// CRC32.cs
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// ------------------------------------------------------------------
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//
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// Copyright (c) 2011 Dino Chiesa.
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// All rights reserved.
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//
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// This code module is part of DotNetZip, a zipfile class library.
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//
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// ------------------------------------------------------------------
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//
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// This code is licensed under the Microsoft Public License.
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// See the file License.txt for the license details.
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// More info on: http://dotnetzip.codeplex.com
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//
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// ------------------------------------------------------------------
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//
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// Last Saved: <2011-August-02 18:25:54>
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//
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// ------------------------------------------------------------------
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//
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// This module defines the CRC32 class, which can do the CRC32 algorithm, using
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// arbitrary starting polynomials, and bit reversal. The bit reversal is what
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// distinguishes this CRC-32 used in BZip2 from the CRC-32 that is used in PKZIP
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// files, or GZIP files. This class does both.
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//
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// ------------------------------------------------------------------
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using System;
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using Interop = System.Runtime.InteropServices;
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namespace HH.WMS.Utils.Ionic.Crc
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{
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/// <summary>
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/// Computes a CRC-32. The CRC-32 algorithm is parameterized - you
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/// can set the polynomial and enable or disable bit
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/// reversal. This can be used for GZIP, BZip2, or ZIP.
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/// </summary>
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/// <remarks>
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/// This type is used internally by DotNetZip; it is generally not used
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/// directly by applications wishing to create, read, or manipulate zip
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/// archive files.
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/// </remarks>
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[Interop.GuidAttribute("ebc25cf6-9120-4283-b972-0e5520d0000C")]
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[Interop.ComVisible(true)]
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#if !NETCF
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[Interop.ClassInterface(Interop.ClassInterfaceType.AutoDispatch)]
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#endif
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public class CRC32
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{
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/// <summary>
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/// Indicates the total number of bytes applied to the CRC.
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/// </summary>
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public Int64 TotalBytesRead
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{
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get
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{
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return _TotalBytesRead;
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}
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}
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/// <summary>
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/// Indicates the current CRC for all blocks slurped in.
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/// </summary>
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public Int32 Crc32Result
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{
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get
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{
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return unchecked((Int32)(~_register));
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}
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}
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/// <summary>
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/// Returns the CRC32 for the specified stream.
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/// </summary>
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/// <param name="input">The stream over which to calculate the CRC32</param>
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/// <returns>the CRC32 calculation</returns>
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public Int32 GetCrc32(System.IO.Stream input)
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{
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return GetCrc32AndCopy(input, null);
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}
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/// <summary>
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/// Returns the CRC32 for the specified stream, and writes the input into the
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/// output stream.
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/// </summary>
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/// <param name="input">The stream over which to calculate the CRC32</param>
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/// <param name="output">The stream into which to deflate the input</param>
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/// <returns>the CRC32 calculation</returns>
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public Int32 GetCrc32AndCopy(System.IO.Stream input, System.IO.Stream output)
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{
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if (input == null)
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throw new Exception("The input stream must not be null.");
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unchecked
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{
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byte[] buffer = new byte[BUFFER_SIZE];
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int readSize = BUFFER_SIZE;
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_TotalBytesRead = 0;
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int count = input.Read(buffer, 0, readSize);
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if (output != null) output.Write(buffer, 0, count);
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_TotalBytesRead += count;
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while (count > 0)
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{
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SlurpBlock(buffer, 0, count);
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count = input.Read(buffer, 0, readSize);
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if (output != null) output.Write(buffer, 0, count);
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_TotalBytesRead += count;
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}
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return (Int32)(~_register);
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}
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}
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/// <summary>
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/// Get the CRC32 for the given (word,byte) combo. This is a
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/// computation defined by PKzip for PKZIP 2.0 (weak) encryption.
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/// </summary>
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/// <param name="W">The word to start with.</param>
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/// <param name="B">The byte to combine it with.</param>
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/// <returns>The CRC-ized result.</returns>
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public Int32 ComputeCrc32(Int32 W, byte B)
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{
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return _InternalComputeCrc32((UInt32)W, B);
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}
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internal Int32 _InternalComputeCrc32(UInt32 W, byte B)
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{
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return (Int32)(crc32Table[(W ^ B) & 0xFF] ^ (W >> 8));
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}
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/// <summary>
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/// Update the value for the running CRC32 using the given block of bytes.
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/// This is useful when using the CRC32() class in a Stream.
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/// </summary>
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/// <param name="block">block of bytes to slurp</param>
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/// <param name="offset">starting point in the block</param>
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/// <param name="count">how many bytes within the block to slurp</param>
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public void SlurpBlock(byte[] block, int offset, int count)
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{
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if (block == null)
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throw new Exception("The data buffer must not be null.");
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// bzip algorithm
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for (int i = 0; i < count; i++)
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{
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int x = offset + i;
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byte b = block[x];
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if (this.reverseBits)
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{
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UInt32 temp = (_register >> 24) ^ b;
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_register = (_register << 8) ^ crc32Table[temp];
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}
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else
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{
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UInt32 temp = (_register & 0x000000FF) ^ b;
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_register = (_register >> 8) ^ crc32Table[temp];
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}
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}
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_TotalBytesRead += count;
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}
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/// <summary>
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/// Process one byte in the CRC.
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/// </summary>
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/// <param name = "b">the byte to include into the CRC . </param>
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public void UpdateCRC(byte b)
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{
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if (this.reverseBits)
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{
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UInt32 temp = (_register >> 24) ^ b;
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_register = (_register << 8) ^ crc32Table[temp];
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}
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else
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{
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UInt32 temp = (_register & 0x000000FF) ^ b;
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_register = (_register >> 8) ^ crc32Table[temp];
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}
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}
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/// <summary>
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/// Process a run of N identical bytes into the CRC.
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/// </summary>
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/// <remarks>
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/// <para>
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/// This method serves as an optimization for updating the CRC when a
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/// run of identical bytes is found. Rather than passing in a buffer of
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/// length n, containing all identical bytes b, this method accepts the
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/// byte value and the length of the (virtual) buffer - the length of
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/// the run.
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/// </para>
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/// </remarks>
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/// <param name = "b">the byte to include into the CRC. </param>
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/// <param name = "n">the number of times that byte should be repeated. </param>
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public void UpdateCRC(byte b, int n)
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{
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while (n-- > 0)
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{
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if (this.reverseBits)
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{
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uint temp = (_register >> 24) ^ b;
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_register = (_register << 8) ^ crc32Table[(temp >= 0)
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? temp
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: (temp + 256)];
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}
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else
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{
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UInt32 temp = (_register & 0x000000FF) ^ b;
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_register = (_register >> 8) ^ crc32Table[(temp >= 0)
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? temp
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: (temp + 256)];
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}
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}
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}
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private static uint ReverseBits(uint data)
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{
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unchecked
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{
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uint ret = data;
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ret = (ret & 0x55555555) << 1 | (ret >> 1) & 0x55555555;
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ret = (ret & 0x33333333) << 2 | (ret >> 2) & 0x33333333;
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ret = (ret & 0x0F0F0F0F) << 4 | (ret >> 4) & 0x0F0F0F0F;
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ret = (ret << 24) | ((ret & 0xFF00) << 8) | ((ret >> 8) & 0xFF00) | (ret >> 24);
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return ret;
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}
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}
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private static byte ReverseBits(byte data)
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{
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unchecked
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{
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uint u = (uint)data * 0x00020202;
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uint m = 0x01044010;
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uint s = u & m;
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uint t = (u << 2) & (m << 1);
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return (byte)((0x01001001 * (s + t)) >> 24);
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}
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}
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private void GenerateLookupTable()
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{
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crc32Table = new UInt32[256];
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unchecked
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{
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UInt32 dwCrc;
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byte i = 0;
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do
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{
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dwCrc = i;
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for (byte j = 8; j > 0; j--)
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{
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if ((dwCrc & 1) == 1)
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{
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dwCrc = (dwCrc >> 1) ^ dwPolynomial;
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}
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else
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{
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dwCrc >>= 1;
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}
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}
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if (reverseBits)
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{
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crc32Table[ReverseBits(i)] = ReverseBits(dwCrc);
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}
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else
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{
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crc32Table[i] = dwCrc;
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}
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i++;
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} while (i!=0);
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}
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#if VERBOSE
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Console.WriteLine();
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Console.WriteLine("private static readonly UInt32[] crc32Table = {");
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for (int i = 0; i < crc32Table.Length; i+=4)
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{
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Console.Write(" ");
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for (int j=0; j < 4; j++)
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{
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Console.Write(" 0x{0:X8}U,", crc32Table[i+j]);
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}
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Console.WriteLine();
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}
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Console.WriteLine("};");
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Console.WriteLine();
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#endif
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}
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private uint gf2_matrix_times(uint[] matrix, uint vec)
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{
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uint sum = 0;
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int i=0;
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while (vec != 0)
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{
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if ((vec & 0x01)== 0x01)
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sum ^= matrix[i];
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vec >>= 1;
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i++;
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}
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return sum;
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}
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private void gf2_matrix_square(uint[] square, uint[] mat)
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{
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for (int i = 0; i < 32; i++)
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square[i] = gf2_matrix_times(mat, mat[i]);
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}
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/// <summary>
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/// Combines the given CRC32 value with the current running total.
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/// </summary>
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/// <remarks>
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/// This is useful when using a divide-and-conquer approach to
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/// calculating a CRC. Multiple threads can each calculate a
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/// CRC32 on a segment of the data, and then combine the
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/// individual CRC32 values at the end.
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/// </remarks>
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/// <param name="crc">the crc value to be combined with this one</param>
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/// <param name="length">the length of data the CRC value was calculated on</param>
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public void Combine(int crc, int length)
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{
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uint[] even = new uint[32]; // even-power-of-two zeros operator
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uint[] odd = new uint[32]; // odd-power-of-two zeros operator
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if (length == 0)
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return;
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uint crc1= ~_register;
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uint crc2= (uint) crc;
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// put operator for one zero bit in odd
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odd[0] = this.dwPolynomial; // the CRC-32 polynomial
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uint row = 1;
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for (int i = 1; i < 32; i++)
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{
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odd[i] = row;
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row <<= 1;
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}
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// put operator for two zero bits in even
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gf2_matrix_square(even, odd);
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// put operator for four zero bits in odd
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gf2_matrix_square(odd, even);
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uint len2 = (uint) length;
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// apply len2 zeros to crc1 (first square will put the operator for one
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// zero byte, eight zero bits, in even)
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do {
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// apply zeros operator for this bit of len2
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gf2_matrix_square(even, odd);
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if ((len2 & 1)== 1)
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crc1 = gf2_matrix_times(even, crc1);
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len2 >>= 1;
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if (len2 == 0)
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break;
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// another iteration of the loop with odd and even swapped
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gf2_matrix_square(odd, even);
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if ((len2 & 1)==1)
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crc1 = gf2_matrix_times(odd, crc1);
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len2 >>= 1;
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} while (len2 != 0);
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crc1 ^= crc2;
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_register= ~crc1;
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//return (int) crc1;
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return;
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}
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/// <summary>
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/// Create an instance of the CRC32 class using the default settings: no
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/// bit reversal, and a polynomial of 0xEDB88320.
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/// </summary>
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public CRC32() : this(false)
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{
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}
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/// <summary>
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/// Create an instance of the CRC32 class, specifying whether to reverse
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/// data bits or not.
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/// </summary>
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/// <param name='reverseBits'>
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/// specify true if the instance should reverse data bits.
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/// </param>
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/// <remarks>
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/// <para>
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/// In the CRC-32 used by BZip2, the bits are reversed. Therefore if you
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/// want a CRC32 with compatibility with BZip2, you should pass true
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/// here. In the CRC-32 used by GZIP and PKZIP, the bits are not
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/// reversed; Therefore if you want a CRC32 with compatibility with
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/// those, you should pass false.
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/// </para>
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/// </remarks>
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public CRC32(bool reverseBits) :
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this( unchecked((int)0xEDB88320), reverseBits)
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{
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}
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/// <summary>
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/// Create an instance of the CRC32 class, specifying the polynomial and
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/// whether to reverse data bits or not.
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/// </summary>
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/// <param name='polynomial'>
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/// The polynomial to use for the CRC, expressed in the reversed (LSB)
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/// format: the highest ordered bit in the polynomial value is the
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/// coefficient of the 0th power; the second-highest order bit is the
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/// coefficient of the 1 power, and so on. Expressed this way, the
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/// polynomial for the CRC-32C used in IEEE 802.3, is 0xEDB88320.
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/// </param>
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/// <param name='reverseBits'>
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/// specify true if the instance should reverse data bits.
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/// </param>
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///
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/// <remarks>
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/// <para>
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/// In the CRC-32 used by BZip2, the bits are reversed. Therefore if you
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/// want a CRC32 with compatibility with BZip2, you should pass true
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/// here for the <c>reverseBits</c> parameter. In the CRC-32 used by
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/// GZIP and PKZIP, the bits are not reversed; Therefore if you want a
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/// CRC32 with compatibility with those, you should pass false for the
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/// <c>reverseBits</c> parameter.
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/// </para>
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/// </remarks>
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public CRC32(int polynomial, bool reverseBits)
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{
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this.reverseBits = reverseBits;
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this.dwPolynomial = (uint) polynomial;
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this.GenerateLookupTable();
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}
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/// <summary>
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/// Reset the CRC-32 class - clear the CRC "remainder register."
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/// </summary>
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/// <remarks>
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/// <para>
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/// Use this when employing a single instance of this class to compute
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/// multiple, distinct CRCs on multiple, distinct data blocks.
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/// </para>
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/// </remarks>
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public void Reset()
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{
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_register = 0xFFFFFFFFU;
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}
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// private member vars
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private UInt32 dwPolynomial;
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private Int64 _TotalBytesRead;
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private bool reverseBits;
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private UInt32[] crc32Table;
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private const int BUFFER_SIZE = 8192;
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private UInt32 _register = 0xFFFFFFFFU;
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}
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/// <summary>
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/// A Stream that calculates a CRC32 (a checksum) on all bytes read,
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/// or on all bytes written.
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/// </summary>
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///
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/// <remarks>
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/// <para>
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/// This class can be used to verify the CRC of a ZipEntry when
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/// reading from a stream, or to calculate a CRC when writing to a
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/// stream. The stream should be used to either read, or write, but
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/// not both. If you intermix reads and writes, the results are not
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/// defined.
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/// </para>
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///
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/// <para>
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/// This class is intended primarily for use internally by the
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/// DotNetZip library.
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/// </para>
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/// </remarks>
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public class CrcCalculatorStream : System.IO.Stream, System.IDisposable
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{
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private static readonly Int64 UnsetLengthLimit = -99;
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internal System.IO.Stream _innerStream;
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private CRC32 _Crc32;
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private Int64 _lengthLimit = -99;
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private bool _leaveOpen;
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/// <summary>
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/// The default constructor.
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/// </summary>
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/// <remarks>
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/// <para>
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/// Instances returned from this constructor will leave the underlying
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/// stream open upon Close(). The stream uses the default CRC32
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/// algorithm, which implies a polynomial of 0xEDB88320.
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/// </para>
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/// </remarks>
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/// <param name="stream">The underlying stream</param>
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public CrcCalculatorStream(System.IO.Stream stream)
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: this(true, CrcCalculatorStream.UnsetLengthLimit, stream, null)
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{
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}
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/// <summary>
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/// The constructor allows the caller to specify how to handle the
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/// underlying stream at close.
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/// </summary>
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/// <remarks>
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/// <para>
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/// The stream uses the default CRC32 algorithm, which implies a
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/// polynomial of 0xEDB88320.
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/// </para>
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/// </remarks>
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/// <param name="stream">The underlying stream</param>
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/// <param name="leaveOpen">true to leave the underlying stream
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/// open upon close of the <c>CrcCalculatorStream</c>; false otherwise.</param>
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public CrcCalculatorStream(System.IO.Stream stream, bool leaveOpen)
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: this(leaveOpen, CrcCalculatorStream.UnsetLengthLimit, stream, null)
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{
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}
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/// <summary>
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/// A constructor allowing the specification of the length of the stream
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/// to read.
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/// </summary>
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/// <remarks>
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/// <para>
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/// The stream uses the default CRC32 algorithm, which implies a
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/// polynomial of 0xEDB88320.
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/// </para>
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/// <para>
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/// Instances returned from this constructor will leave the underlying
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/// stream open upon Close().
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/// </para>
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/// </remarks>
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/// <param name="stream">The underlying stream</param>
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/// <param name="length">The length of the stream to slurp</param>
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public CrcCalculatorStream(System.IO.Stream stream, Int64 length)
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: this(true, length, stream, null)
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{
|
if (length < 0)
|
throw new ArgumentException("length");
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}
|
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/// <summary>
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/// A constructor allowing the specification of the length of the stream
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/// to read, as well as whether to keep the underlying stream open upon
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/// Close().
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/// </summary>
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/// <remarks>
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/// <para>
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/// The stream uses the default CRC32 algorithm, which implies a
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/// polynomial of 0xEDB88320.
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/// </para>
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/// </remarks>
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/// <param name="stream">The underlying stream</param>
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/// <param name="length">The length of the stream to slurp</param>
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/// <param name="leaveOpen">true to leave the underlying stream
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/// open upon close of the <c>CrcCalculatorStream</c>; false otherwise.</param>
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public CrcCalculatorStream(System.IO.Stream stream, Int64 length, bool leaveOpen)
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: this(leaveOpen, length, stream, null)
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{
|
if (length < 0)
|
throw new ArgumentException("length");
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}
|
|
/// <summary>
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/// A constructor allowing the specification of the length of the stream
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/// to read, as well as whether to keep the underlying stream open upon
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/// Close(), and the CRC32 instance to use.
|
/// </summary>
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/// <remarks>
|
/// <para>
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/// The stream uses the specified CRC32 instance, which allows the
|
/// application to specify how the CRC gets calculated.
|
/// </para>
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/// </remarks>
|
/// <param name="stream">The underlying stream</param>
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/// <param name="length">The length of the stream to slurp</param>
|
/// <param name="leaveOpen">true to leave the underlying stream
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/// open upon close of the <c>CrcCalculatorStream</c>; false otherwise.</param>
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/// <param name="crc32">the CRC32 instance to use to calculate the CRC32</param>
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public CrcCalculatorStream(System.IO.Stream stream, Int64 length, bool leaveOpen,
|
CRC32 crc32)
|
: this(leaveOpen, length, stream, crc32)
|
{
|
if (length < 0)
|
throw new ArgumentException("length");
|
}
|
|
|
// This ctor is private - no validation is done here. This is to allow the use
|
// of a (specific) negative value for the _lengthLimit, to indicate that there
|
// is no length set. So we validate the length limit in those ctors that use an
|
// explicit param, otherwise we don't validate, because it could be our special
|
// value.
|
private CrcCalculatorStream
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(bool leaveOpen, Int64 length, System.IO.Stream stream, CRC32 crc32)
|
: base()
|
{
|
_innerStream = stream;
|
_Crc32 = crc32 ?? new CRC32();
|
_lengthLimit = length;
|
_leaveOpen = leaveOpen;
|
}
|
|
|
/// <summary>
|
/// Gets the total number of bytes run through the CRC32 calculator.
|
/// </summary>
|
///
|
/// <remarks>
|
/// This is either the total number of bytes read, or the total number of
|
/// bytes written, depending on the direction of this stream.
|
/// </remarks>
|
public Int64 TotalBytesSlurped
|
{
|
get { return _Crc32.TotalBytesRead; }
|
}
|
|
/// <summary>
|
/// Provides the current CRC for all blocks slurped in.
|
/// </summary>
|
/// <remarks>
|
/// <para>
|
/// The running total of the CRC is kept as data is written or read
|
/// through the stream. read this property after all reads or writes to
|
/// get an accurate CRC for the entire stream.
|
/// </para>
|
/// </remarks>
|
public Int32 Crc
|
{
|
get { return _Crc32.Crc32Result; }
|
}
|
|
/// <summary>
|
/// Indicates whether the underlying stream will be left open when the
|
/// <c>CrcCalculatorStream</c> is Closed.
|
/// </summary>
|
/// <remarks>
|
/// <para>
|
/// Set this at any point before calling <see cref="Close()"/>.
|
/// </para>
|
/// </remarks>
|
public bool LeaveOpen
|
{
|
get { return _leaveOpen; }
|
set { _leaveOpen = value; }
|
}
|
|
/// <summary>
|
/// Read from the stream
|
/// </summary>
|
/// <param name="buffer">the buffer to read</param>
|
/// <param name="offset">the offset at which to start</param>
|
/// <param name="count">the number of bytes to read</param>
|
/// <returns>the number of bytes actually read</returns>
|
public override int Read(byte[] buffer, int offset, int count)
|
{
|
int bytesToRead = count;
|
|
// Need to limit the # of bytes returned, if the stream is intended to have
|
// a definite length. This is especially useful when returning a stream for
|
// the uncompressed data directly to the application. The app won't
|
// necessarily read only the UncompressedSize number of bytes. For example
|
// wrapping the stream returned from OpenReader() into a StreadReader() and
|
// calling ReadToEnd() on it, We can "over-read" the zip data and get a
|
// corrupt string. The length limits that, prevents that problem.
|
|
if (_lengthLimit != CrcCalculatorStream.UnsetLengthLimit)
|
{
|
if (_Crc32.TotalBytesRead >= _lengthLimit) return 0; // EOF
|
Int64 bytesRemaining = _lengthLimit - _Crc32.TotalBytesRead;
|
if (bytesRemaining < count) bytesToRead = (int)bytesRemaining;
|
}
|
int n = _innerStream.Read(buffer, offset, bytesToRead);
|
if (n > 0) _Crc32.SlurpBlock(buffer, offset, n);
|
return n;
|
}
|
|
/// <summary>
|
/// Write to the stream.
|
/// </summary>
|
/// <param name="buffer">the buffer from which to write</param>
|
/// <param name="offset">the offset at which to start writing</param>
|
/// <param name="count">the number of bytes to write</param>
|
public override void Write(byte[] buffer, int offset, int count)
|
{
|
if (count > 0) _Crc32.SlurpBlock(buffer, offset, count);
|
_innerStream.Write(buffer, offset, count);
|
}
|
|
/// <summary>
|
/// Indicates whether the stream supports reading.
|
/// </summary>
|
public override bool CanRead
|
{
|
get { return _innerStream.CanRead; }
|
}
|
|
/// <summary>
|
/// Indicates whether the stream supports seeking.
|
/// </summary>
|
/// <remarks>
|
/// <para>
|
/// Always returns false.
|
/// </para>
|
/// </remarks>
|
public override bool CanSeek
|
{
|
get { return false; }
|
}
|
|
/// <summary>
|
/// Indicates whether the stream supports writing.
|
/// </summary>
|
public override bool CanWrite
|
{
|
get { return _innerStream.CanWrite; }
|
}
|
|
/// <summary>
|
/// Flush the stream.
|
/// </summary>
|
public override void Flush()
|
{
|
_innerStream.Flush();
|
}
|
|
/// <summary>
|
/// Returns the length of the underlying stream.
|
/// </summary>
|
public override long Length
|
{
|
get
|
{
|
if (_lengthLimit == CrcCalculatorStream.UnsetLengthLimit)
|
return _innerStream.Length;
|
else return _lengthLimit;
|
}
|
}
|
|
/// <summary>
|
/// The getter for this property returns the total bytes read.
|
/// If you use the setter, it will throw
|
/// <see cref="NotSupportedException"/>.
|
/// </summary>
|
public override long Position
|
{
|
get { return _Crc32.TotalBytesRead; }
|
set { throw new NotSupportedException(); }
|
}
|
|
/// <summary>
|
/// Seeking is not supported on this stream. This method always throws
|
/// <see cref="NotSupportedException"/>
|
/// </summary>
|
/// <param name="offset">N/A</param>
|
/// <param name="origin">N/A</param>
|
/// <returns>N/A</returns>
|
public override long Seek(long offset, System.IO.SeekOrigin origin)
|
{
|
throw new NotSupportedException();
|
}
|
|
/// <summary>
|
/// This method always throws
|
/// <see cref="NotSupportedException"/>
|
/// </summary>
|
/// <param name="value">N/A</param>
|
public override void SetLength(long value)
|
{
|
throw new NotSupportedException();
|
}
|
|
|
void IDisposable.Dispose()
|
{
|
Close();
|
}
|
|
/// <summary>
|
/// Closes the stream.
|
/// </summary>
|
public override void Close()
|
{
|
base.Close();
|
if (!_leaveOpen)
|
_innerStream.Close();
|
}
|
|
}
|
|
}
|
