202 lines
7.7 KiB
C#
202 lines
7.7 KiB
C#
//
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// © Copyright Henrik Ravn 2004
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//
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// Use, modification and distribution are subject to the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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using System;
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using System.Runtime.InteropServices;
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using System.Text;
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namespace DotZLib
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{
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#region ChecksumGeneratorBase
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/// <summary>
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/// Implements the common functionality needed for all <see cref="ChecksumGenerator"/>s
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/// </summary>
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/// <example></example>
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public abstract class ChecksumGeneratorBase : ChecksumGenerator
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{
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/// <summary>
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/// The value of the current checksum
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/// </summary>
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protected uint _current;
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/// <summary>
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/// Initializes a new instance of the checksum generator base - the current checksum is
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/// set to zero
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/// </summary>
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public ChecksumGeneratorBase()
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{
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_current = 0;
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}
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/// <summary>
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/// Initializes a new instance of the checksum generator basewith a specified value
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/// </summary>
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/// <param name="initialValue">The value to set the current checksum to</param>
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public ChecksumGeneratorBase(uint initialValue)
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{
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_current = initialValue;
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}
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/// <summary>
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/// Resets the current checksum to zero
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/// </summary>
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public void Reset() { _current = 0; }
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/// <summary>
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/// Gets the current checksum value
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/// </summary>
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public uint Value { get { return _current; } }
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/// <summary>
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/// Updates the current checksum with part of an array of bytes
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/// </summary>
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/// <param name="data">The data to update the checksum with</param>
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/// <param name="offset">Where in <c>data</c> to start updating</param>
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/// <param name="count">The number of bytes from <c>data</c> to use</param>
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/// <exception cref="ArgumentException">The sum of offset and count is larger than the length of <c>data</c></exception>
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/// <exception cref="NullReferenceException"><c>data</c> is a null reference</exception>
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/// <exception cref="ArgumentOutOfRangeException">Offset or count is negative.</exception>
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/// <remarks>All the other <c>Update</c> methods are implmeneted in terms of this one.
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/// This is therefore the only method a derived class has to implement</remarks>
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public abstract void Update(byte[] data, int offset, int count);
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/// <summary>
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/// Updates the current checksum with an array of bytes.
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/// </summary>
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/// <param name="data">The data to update the checksum with</param>
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public void Update(byte[] data)
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{
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Update(data, 0, data.Length);
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}
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/// <summary>
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/// Updates the current checksum with the data from a string
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/// </summary>
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/// <param name="data">The string to update the checksum with</param>
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/// <remarks>The characters in the string are converted by the UTF-8 encoding</remarks>
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public void Update(string data)
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{
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Update(Encoding.UTF8.GetBytes(data));
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}
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/// <summary>
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/// Updates the current checksum with the data from a string, using a specific encoding
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/// </summary>
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/// <param name="data">The string to update the checksum with</param>
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/// <param name="encoding">The encoding to use</param>
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public void Update(string data, Encoding encoding)
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{
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Update(encoding.GetBytes(data));
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}
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}
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#endregion
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#region CRC32
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/// <summary>
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/// Implements a CRC32 checksum generator
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/// </summary>
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public sealed class CRC32Checksum : ChecksumGeneratorBase
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{
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#region DLL imports
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[DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
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private static extern uint crc32(uint crc, int data, uint length);
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#endregion
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/// <summary>
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/// Initializes a new instance of the CRC32 checksum generator
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/// </summary>
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public CRC32Checksum() : base() {}
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/// <summary>
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/// Initializes a new instance of the CRC32 checksum generator with a specified value
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/// </summary>
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/// <param name="initialValue">The value to set the current checksum to</param>
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public CRC32Checksum(uint initialValue) : base(initialValue) {}
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/// <summary>
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/// Updates the current checksum with part of an array of bytes
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/// </summary>
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/// <param name="data">The data to update the checksum with</param>
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/// <param name="offset">Where in <c>data</c> to start updating</param>
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/// <param name="count">The number of bytes from <c>data</c> to use</param>
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/// <exception cref="ArgumentException">The sum of offset and count is larger than the length of <c>data</c></exception>
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/// <exception cref="NullReferenceException"><c>data</c> is a null reference</exception>
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/// <exception cref="ArgumentOutOfRangeException">Offset or count is negative.</exception>
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public override void Update(byte[] data, int offset, int count)
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{
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if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
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if ((offset+count) > data.Length) throw new ArgumentException();
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GCHandle hData = GCHandle.Alloc(data, GCHandleType.Pinned);
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try
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{
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_current = crc32(_current, hData.AddrOfPinnedObject().ToInt32()+offset, (uint)count);
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}
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finally
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{
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hData.Free();
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}
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}
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}
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#endregion
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#region Adler
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/// <summary>
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/// Implements a checksum generator that computes the Adler checksum on data
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/// </summary>
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public sealed class AdlerChecksum : ChecksumGeneratorBase
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{
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#region DLL imports
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[DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
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private static extern uint adler32(uint adler, int data, uint length);
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#endregion
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/// <summary>
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/// Initializes a new instance of the Adler checksum generator
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/// </summary>
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public AdlerChecksum() : base() {}
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/// <summary>
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/// Initializes a new instance of the Adler checksum generator with a specified value
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/// </summary>
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/// <param name="initialValue">The value to set the current checksum to</param>
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public AdlerChecksum(uint initialValue) : base(initialValue) {}
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/// <summary>
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/// Updates the current checksum with part of an array of bytes
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/// </summary>
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/// <param name="data">The data to update the checksum with</param>
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/// <param name="offset">Where in <c>data</c> to start updating</param>
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/// <param name="count">The number of bytes from <c>data</c> to use</param>
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/// <exception cref="ArgumentException">The sum of offset and count is larger than the length of <c>data</c></exception>
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/// <exception cref="NullReferenceException"><c>data</c> is a null reference</exception>
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/// <exception cref="ArgumentOutOfRangeException">Offset or count is negative.</exception>
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public override void Update(byte[] data, int offset, int count)
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{
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if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
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if ((offset+count) > data.Length) throw new ArgumentException();
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GCHandle hData = GCHandle.Alloc(data, GCHandleType.Pinned);
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try
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{
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_current = adler32(_current, hData.AddrOfPinnedObject().ToInt32()+offset, (uint)count);
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}
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finally
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{
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hData.Free();
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}
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}
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}
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#endregion
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} |