Initial project's source code check-in.

WebsitePanel.Installer/Sources/WebsitePanel.Setup/Common/CRC32.cs

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+// Copyright (c) 2011, Outercurve Foundation.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without modification,
+// are permitted provided that the following conditions are met:
+//
+// - Redistributions of source code must  retain  the  above copyright notice, this
+//   list of conditions and the following disclaimer.
+//
+// - Redistributions in binary form  must  reproduce the  above  copyright  notice,
+//   this list of conditions  and  the  following  disclaimer in  the documentation
+//   and/or other materials provided with the distribution.
+//
+// - Neither  the  name  of  the  Outercurve Foundation  nor   the   names  of  its
+//   contributors may be used to endorse or  promote  products  derived  from  this
+//   software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,  BUT  NOT  LIMITED TO, THE IMPLIED
+// WARRANTIES  OF  MERCHANTABILITY   AND  FITNESS  FOR  A  PARTICULAR  PURPOSE  ARE
+// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+// ANY DIRECT, INDIRECT, INCIDENTAL,  SPECIAL,  EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+// (INCLUDING, BUT NOT LIMITED TO,  PROCUREMENT  OF  SUBSTITUTE  GOODS OR SERVICES;
+// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)  HOWEVER  CAUSED AND ON
+// ANY  THEORY  OF  LIABILITY,  WHETHER  IN  CONTRACT,  STRICT  LIABILITY,  OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE)  ARISING  IN  ANY WAY OUT OF THE USE OF THIS
+// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+using System;
+using System.Collections;
+using System.IO;
+using System.Security.Cryptography;
+
+namespace WebsitePanel.Setup
+{
+	internal class CRC32 : HashAlgorithm
+	{
+		protected static uint AllOnes = 0xffffffff;
+		protected static Hashtable cachedCRC32Tables;
+		protected static bool autoCache;
+
+		protected uint[] crc32Table;
+		private uint m_crc;
+
+		/// <summary>
+		/// Returns the default polynomial (used in WinZip, Ethernet, etc)
+		/// </summary>
+		public static uint DefaultPolynomial
+		{
+			get { return 0x04C11DB7; }
+		}
+
+		/// <summary>
+		/// Gets or sets the auto-cache setting of this class.
+		/// </summary>
+		public static bool AutoCache
+		{
+			get { return autoCache; }
+			set { autoCache = value; }
+		}
+
+		/// <summary>
+		/// Initialize the cache
+		/// </summary>
+		static CRC32()
+		{
+			cachedCRC32Tables = Hashtable.Synchronized(new Hashtable());
+			autoCache = true;
+		}
+
+		public static void ClearCache()
+		{
+			cachedCRC32Tables.Clear();
+		}
+
+
+		/// <summary>
+		/// Builds a crc32 table given a polynomial
+		/// </summary>
+		/// <param name="ulPolynomial"></param>
+		/// <returns></returns>
+		protected static uint[] BuildCRC32Table(uint ulPolynomial)
+		{
+			uint dwCrc;
+			uint[] table = new uint[256];
+
+			// 256 values representing ASCII character codes. 
+			for (int i = 0; i < 256; i++)
+			{
+				dwCrc = (uint)i;
+				for (int j = 8; j > 0; j--)
+				{
+					if ((dwCrc & 1) == 1)
+						dwCrc = (dwCrc >> 1) ^ ulPolynomial;
+					else
+						dwCrc >>= 1;
+				}
+				table[i] = dwCrc;
+			}
+
+			return table;
+		}
+
+
+		/// <summary>
+		/// Creates a CRC32 object using the DefaultPolynomial
+		/// </summary>
+		public CRC32()
+			: this(DefaultPolynomial)
+		{
+		}
+
+		/// <summary>
+		/// Creates a CRC32 object using the specified Creates a CRC32 object 
+		/// </summary>
+		public CRC32(uint aPolynomial)
+			: this(aPolynomial, CRC32.AutoCache)
+		{
+		}
+
+		/// <summary>
+		/// Construct the 
+		/// </summary>
+		public CRC32(uint aPolynomial, bool cacheTable)
+		{
+			this.HashSizeValue = 32;
+
+			crc32Table = (uint[])cachedCRC32Tables[aPolynomial];
+			if (crc32Table == null)
+			{
+				crc32Table = CRC32.BuildCRC32Table(aPolynomial);
+				if (cacheTable)
+					cachedCRC32Tables.Add(aPolynomial, crc32Table);
+			}
+			Initialize();
+		}
+
+		/// <summary>
+		/// Initializes an implementation of HashAlgorithm.
+		/// </summary>
+		public override void Initialize()
+		{
+			m_crc = AllOnes;
+		}
+
+		/// <summary>
+		/// 
+		/// </summary>
+		/// <param name="buffer"></param>
+		/// <param name="offset"></param>
+		/// <param name="count"></param>
+		protected override void HashCore(byte[] buffer, int offset, int count)
+		{
+			// Save the text in the buffer. 
+			for (int i = offset; i < count; i++)
+			{
+				ulong tabPtr = (m_crc & 0xFF) ^ buffer[i];
+				m_crc >>= 8;
+				m_crc ^= crc32Table[tabPtr];
+			}
+		}
+
+		/// <summary>
+		/// 
+		/// </summary>
+		/// <returns></returns>
+		protected override byte[] HashFinal()
+		{
+			byte[] finalHash = new byte[4];
+			ulong finalCRC = m_crc ^ AllOnes;
+
+			finalHash[0] = (byte)((finalCRC >> 24) & 0xFF);
+			finalHash[1] = (byte)((finalCRC >> 16) & 0xFF);
+			finalHash[2] = (byte)((finalCRC >> 8) & 0xFF);
+			finalHash[3] = (byte)((finalCRC >> 0) & 0xFF);
+
+			return finalHash;
+		}
+
+		/// <summary>
+		/// Computes the hash value for the specified Stream.
+		/// </summary>
+		new public byte[] ComputeHash(Stream inputStream)
+		{
+			byte[] buffer = new byte[4096];
+			int bytesRead;
+			while ((bytesRead = inputStream.Read(buffer, 0, 4096)) > 0)
+			{
+				HashCore(buffer, 0, bytesRead);
+			}
+			return HashFinal();
+		}
+
+
+		/// <summary>
+		/// Overloaded. Computes the hash value for the input data.
+		/// </summary>
+		new public byte[] ComputeHash(byte[] buffer)
+		{
+			return ComputeHash(buffer, 0, buffer.Length);
+		}
+
+		/// <summary>
+		/// Overloaded. Computes the hash value for the input data.
+		/// </summary>
+		/// <param name="buffer"></param>
+		/// <param name="offset"></param>
+		/// <param name="count"></param>
+		/// <returns></returns>
+		new public byte[] ComputeHash(byte[] buffer, int offset, int count)
+		{
+			HashCore(buffer, offset, count);
+			return HashFinal();
+		}
+
+	}
+}