Chris@43: //
Chris@43: // © Copyright Henrik Ravn 2004
Chris@43: //
Chris@43: // Use, modification and distribution are subject to the Boost Software License, Version 1.0.
Chris@43: // (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@43: //
Chris@43: 
Chris@43: using System;
Chris@43: using System.Runtime.InteropServices;
Chris@43: using System.Text;
Chris@43: 
Chris@43: 
Chris@43: namespace DotZLib
Chris@43: {
Chris@43:     #region ChecksumGeneratorBase
Chris@43:     /// <summary>
Chris@43:     /// Implements the common functionality needed for all <see cref="ChecksumGenerator"/>s
Chris@43:     /// </summary>
Chris@43:     /// <example></example>
Chris@43:     public abstract class ChecksumGeneratorBase : ChecksumGenerator
Chris@43:     {
Chris@43:         /// <summary>
Chris@43:         /// The value of the current checksum
Chris@43:         /// </summary>
Chris@43:         protected uint _current;
Chris@43: 
Chris@43:         /// <summary>
Chris@43:         /// Initializes a new instance of the checksum generator base - the current checksum is
Chris@43:         /// set to zero
Chris@43:         /// </summary>
Chris@43:         public ChecksumGeneratorBase()
Chris@43:         {
Chris@43:             _current = 0;
Chris@43:         }
Chris@43: 
Chris@43:         /// <summary>
Chris@43:         /// Initializes a new instance of the checksum generator basewith a specified value
Chris@43:         /// </summary>
Chris@43:         /// <param name="initialValue">The value to set the current checksum to</param>
Chris@43:         public ChecksumGeneratorBase(uint initialValue)
Chris@43:         {
Chris@43:             _current = initialValue;
Chris@43:         }
Chris@43: 
Chris@43:         /// <summary>
Chris@43:         /// Resets the current checksum to zero
Chris@43:         /// </summary>
Chris@43:         public void Reset() { _current = 0; }
Chris@43: 
Chris@43:         /// <summary>
Chris@43:         /// Gets the current checksum value
Chris@43:         /// </summary>
Chris@43:         public uint Value { get { return _current; } }
Chris@43: 
Chris@43:         /// <summary>
Chris@43:         /// Updates the current checksum with part of an array of bytes
Chris@43:         /// </summary>
Chris@43:         /// <param name="data">The data to update the checksum with</param>
Chris@43:         /// <param name="offset">Where in <c>data</c> to start updating</param>
Chris@43:         /// <param name="count">The number of bytes from <c>data</c> to use</param>
Chris@43:         /// <exception cref="ArgumentException">The sum of offset and count is larger than the length of <c>data</c></exception>
Chris@43:         /// <exception cref="NullReferenceException"><c>data</c> is a null reference</exception>
Chris@43:         /// <exception cref="ArgumentOutOfRangeException">Offset or count is negative.</exception>
Chris@43:         /// <remarks>All the other <c>Update</c> methods are implmeneted in terms of this one.
Chris@43:         /// This is therefore the only method a derived class has to implement</remarks>
Chris@43:         public abstract void Update(byte[] data, int offset, int count);
Chris@43: 
Chris@43:         /// <summary>
Chris@43:         /// Updates the current checksum with an array of bytes.
Chris@43:         /// </summary>
Chris@43:         /// <param name="data">The data to update the checksum with</param>
Chris@43:         public void Update(byte[] data)
Chris@43:         {
Chris@43:             Update(data, 0, data.Length);
Chris@43:         }
Chris@43: 
Chris@43:         /// <summary>
Chris@43:         /// Updates the current checksum with the data from a string
Chris@43:         /// </summary>
Chris@43:         /// <param name="data">The string to update the checksum with</param>
Chris@43:         /// <remarks>The characters in the string are converted by the UTF-8 encoding</remarks>
Chris@43:         public void Update(string data)
Chris@43:         {
Chris@43: 			Update(Encoding.UTF8.GetBytes(data));
Chris@43:         }
Chris@43: 
Chris@43:         /// <summary>
Chris@43:         /// Updates the current checksum with the data from a string, using a specific encoding
Chris@43:         /// </summary>
Chris@43:         /// <param name="data">The string to update the checksum with</param>
Chris@43:         /// <param name="encoding">The encoding to use</param>
Chris@43:         public void Update(string data, Encoding encoding)
Chris@43:         {
Chris@43:             Update(encoding.GetBytes(data));
Chris@43:         }
Chris@43: 
Chris@43:     }
Chris@43:     #endregion
Chris@43: 
Chris@43:     #region CRC32
Chris@43:     /// <summary>
Chris@43:     /// Implements a CRC32 checksum generator
Chris@43:     /// </summary>
Chris@43:     public sealed class CRC32Checksum : ChecksumGeneratorBase
Chris@43:     {
Chris@43:         #region DLL imports
Chris@43: 
Chris@43:         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
Chris@43:         private static extern uint crc32(uint crc, int data, uint length);
Chris@43: 
Chris@43:         #endregion
Chris@43: 
Chris@43:         /// <summary>
Chris@43:         /// Initializes a new instance of the CRC32 checksum generator
Chris@43:         /// </summary>
Chris@43:         public CRC32Checksum() : base() {}
Chris@43: 
Chris@43:         /// <summary>
Chris@43:         /// Initializes a new instance of the CRC32 checksum generator with a specified value
Chris@43:         /// </summary>
Chris@43:         /// <param name="initialValue">The value to set the current checksum to</param>
Chris@43:         public CRC32Checksum(uint initialValue) : base(initialValue) {}
Chris@43: 
Chris@43:         /// <summary>
Chris@43:         /// Updates the current checksum with part of an array of bytes
Chris@43:         /// </summary>
Chris@43:         /// <param name="data">The data to update the checksum with</param>
Chris@43:         /// <param name="offset">Where in <c>data</c> to start updating</param>
Chris@43:         /// <param name="count">The number of bytes from <c>data</c> to use</param>
Chris@43:         /// <exception cref="ArgumentException">The sum of offset and count is larger than the length of <c>data</c></exception>
Chris@43:         /// <exception cref="NullReferenceException"><c>data</c> is a null reference</exception>
Chris@43:         /// <exception cref="ArgumentOutOfRangeException">Offset or count is negative.</exception>
Chris@43:         public override void Update(byte[] data, int offset, int count)
Chris@43:         {
Chris@43:             if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
Chris@43:             if ((offset+count) > data.Length) throw new ArgumentException();
Chris@43:             GCHandle hData = GCHandle.Alloc(data, GCHandleType.Pinned);
Chris@43:             try
Chris@43:             {
Chris@43:                 _current = crc32(_current, hData.AddrOfPinnedObject().ToInt32()+offset, (uint)count);
Chris@43:             }
Chris@43:             finally
Chris@43:             {
Chris@43:                 hData.Free();
Chris@43:             }
Chris@43:         }
Chris@43: 
Chris@43:     }
Chris@43:     #endregion
Chris@43: 
Chris@43:     #region Adler
Chris@43:     /// <summary>
Chris@43:     /// Implements a checksum generator that computes the Adler checksum on data
Chris@43:     /// </summary>
Chris@43:     public sealed class AdlerChecksum : ChecksumGeneratorBase
Chris@43:     {
Chris@43:         #region DLL imports
Chris@43: 
Chris@43:         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
Chris@43:         private static extern uint adler32(uint adler, int data, uint length);
Chris@43: 
Chris@43:         #endregion
Chris@43: 
Chris@43:         /// <summary>
Chris@43:         /// Initializes a new instance of the Adler checksum generator
Chris@43:         /// </summary>
Chris@43:         public AdlerChecksum() : base() {}
Chris@43: 
Chris@43:         /// <summary>
Chris@43:         /// Initializes a new instance of the Adler checksum generator with a specified value
Chris@43:         /// </summary>
Chris@43:         /// <param name="initialValue">The value to set the current checksum to</param>
Chris@43:         public AdlerChecksum(uint initialValue) : base(initialValue) {}
Chris@43: 
Chris@43:         /// <summary>
Chris@43:         /// Updates the current checksum with part of an array of bytes
Chris@43:         /// </summary>
Chris@43:         /// <param name="data">The data to update the checksum with</param>
Chris@43:         /// <param name="offset">Where in <c>data</c> to start updating</param>
Chris@43:         /// <param name="count">The number of bytes from <c>data</c> to use</param>
Chris@43:         /// <exception cref="ArgumentException">The sum of offset and count is larger than the length of <c>data</c></exception>
Chris@43:         /// <exception cref="NullReferenceException"><c>data</c> is a null reference</exception>
Chris@43:         /// <exception cref="ArgumentOutOfRangeException">Offset or count is negative.</exception>
Chris@43:         public override void Update(byte[] data, int offset, int count)
Chris@43:         {
Chris@43:             if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
Chris@43:             if ((offset+count) > data.Length) throw new ArgumentException();
Chris@43:             GCHandle hData = GCHandle.Alloc(data, GCHandleType.Pinned);
Chris@43:             try
Chris@43:             {
Chris@43:                 _current = adler32(_current, hData.AddrOfPinnedObject().ToInt32()+offset, (uint)count);
Chris@43:             }
Chris@43:             finally
Chris@43:             {
Chris@43:                 hData.Free();
Chris@43:             }
Chris@43:         }
Chris@43: 
Chris@43:     }
Chris@43:     #endregion
Chris@43: 
Chris@43: }