Initial project's source code check-in.

WebsitePanel/Sources/Tools/WebsitePanel.FilesComparer/CRC32.cs

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+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace WebsitePanel.FilesComparer
+{
+	public class CRC32
+	{
+		private UInt32[] crc32Table;
+		private const int BUFFER_SIZE = 1024;
+
+		/// <summary>
+		/// Returns the CRC32 for the specified stream.
+		/// </summary>
+		/// <param name="stream">The stream to calculate the CRC32 for</param>
+		/// <returns>An unsigned integer containing the CRC32 calculation</returns>
+		public UInt32 GetCrc32(System.IO.Stream stream)
+		{
+			unchecked
+			{
+				UInt32 crc32Result;
+				crc32Result = 0xFFFFFFFF;
+				byte[] buffer = new byte[BUFFER_SIZE];
+				int readSize = BUFFER_SIZE;
+
+				int count = stream.Read(buffer, 0, readSize);
+				while (count > 0)
+				{
+					for (int i = 0; i < count; i++)
+					{
+						crc32Result = ((crc32Result) >> 8) ^ crc32Table[(buffer[i]) ^ ((crc32Result) & 0x000000FF)];
+					}
+					count = stream.Read(buffer, 0, readSize);
+				}
+
+				return ~crc32Result;
+			}
+		}
+
+		/// <summary>
+		/// Construct an instance of the CRC32 class, pre-initialising the table
+		/// for speed of lookup.
+		/// </summary>
+		public CRC32()
+		{
+			unchecked
+			{
+				// This is the official polynomial used by CRC32 in PKZip.
+				// Often the polynomial is shown reversed as 0x04C11DB7.
+				UInt32 dwPolynomial = 0xEDB88320;
+				UInt32 i, j;
+
+				crc32Table = new UInt32[256];
+
+				UInt32 dwCrc;
+				for (i = 0; i < 256; i++)
+				{
+					dwCrc = i;
+					for (j = 8; j > 0; j--)
+					{
+						if ((dwCrc & 1) == 1)
+						{
+							dwCrc = (dwCrc >> 1) ^ dwPolynomial;
+						}
+						else
+						{
+							dwCrc >>= 1;
+						}
+					}
+					crc32Table[i] = dwCrc;
+				}
+			}
+		}
+	}
+}