cannam@89: //
cannam@89: // © Copyright Henrik Ravn 2004
cannam@89: //
cannam@89: // Use, modification and distribution are subject to the Boost Software License, Version 1.0.
cannam@89: // (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
cannam@89: //
cannam@89: 
cannam@89: using System;
cannam@89: using System.Runtime.InteropServices;
cannam@89: using System.Text;
cannam@89: 
cannam@89: 
cannam@89: namespace DotZLib
cannam@89: {
cannam@89:     #region ChecksumGeneratorBase
cannam@89:     /// <summary>
cannam@89:     /// Implements the common functionality needed for all <see cref="ChecksumGenerator"/>s
cannam@89:     /// </summary>
cannam@89:     /// <example></example>
cannam@89:     public abstract class ChecksumGeneratorBase : ChecksumGenerator
cannam@89:     {
cannam@89:         /// <summary>
cannam@89:         /// The value of the current checksum
cannam@89:         /// </summary>
cannam@89:         protected uint _current;
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Initializes a new instance of the checksum generator base - the current checksum is
cannam@89:         /// set to zero
cannam@89:         /// </summary>
cannam@89:         public ChecksumGeneratorBase()
cannam@89:         {
cannam@89:             _current = 0;
cannam@89:         }
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Initializes a new instance of the checksum generator basewith a specified value
cannam@89:         /// </summary>
cannam@89:         /// <param name="initialValue">The value to set the current checksum to</param>
cannam@89:         public ChecksumGeneratorBase(uint initialValue)
cannam@89:         {
cannam@89:             _current = initialValue;
cannam@89:         }
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Resets the current checksum to zero
cannam@89:         /// </summary>
cannam@89:         public void Reset() { _current = 0; }
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Gets the current checksum value
cannam@89:         /// </summary>
cannam@89:         public uint Value { get { return _current; } }
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Updates the current checksum with part of an array of bytes
cannam@89:         /// </summary>
cannam@89:         /// <param name="data">The data to update the checksum with</param>
cannam@89:         /// <param name="offset">Where in <c>data</c> to start updating</param>
cannam@89:         /// <param name="count">The number of bytes from <c>data</c> to use</param>
cannam@89:         /// <exception cref="ArgumentException">The sum of offset and count is larger than the length of <c>data</c></exception>
cannam@89:         /// <exception cref="NullReferenceException"><c>data</c> is a null reference</exception>
cannam@89:         /// <exception cref="ArgumentOutOfRangeException">Offset or count is negative.</exception>
cannam@89:         /// <remarks>All the other <c>Update</c> methods are implmeneted in terms of this one.
cannam@89:         /// This is therefore the only method a derived class has to implement</remarks>
cannam@89:         public abstract void Update(byte[] data, int offset, int count);
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Updates the current checksum with an array of bytes.
cannam@89:         /// </summary>
cannam@89:         /// <param name="data">The data to update the checksum with</param>
cannam@89:         public void Update(byte[] data)
cannam@89:         {
cannam@89:             Update(data, 0, data.Length);
cannam@89:         }
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Updates the current checksum with the data from a string
cannam@89:         /// </summary>
cannam@89:         /// <param name="data">The string to update the checksum with</param>
cannam@89:         /// <remarks>The characters in the string are converted by the UTF-8 encoding</remarks>
cannam@89:         public void Update(string data)
cannam@89:         {
cannam@89: 			Update(Encoding.UTF8.GetBytes(data));
cannam@89:         }
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Updates the current checksum with the data from a string, using a specific encoding
cannam@89:         /// </summary>
cannam@89:         /// <param name="data">The string to update the checksum with</param>
cannam@89:         /// <param name="encoding">The encoding to use</param>
cannam@89:         public void Update(string data, Encoding encoding)
cannam@89:         {
cannam@89:             Update(encoding.GetBytes(data));
cannam@89:         }
cannam@89: 
cannam@89:     }
cannam@89:     #endregion
cannam@89: 
cannam@89:     #region CRC32
cannam@89:     /// <summary>
cannam@89:     /// Implements a CRC32 checksum generator
cannam@89:     /// </summary>
cannam@89:     public sealed class CRC32Checksum : ChecksumGeneratorBase
cannam@89:     {
cannam@89:         #region DLL imports
cannam@89: 
cannam@89:         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
cannam@89:         private static extern uint crc32(uint crc, int data, uint length);
cannam@89: 
cannam@89:         #endregion
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Initializes a new instance of the CRC32 checksum generator
cannam@89:         /// </summary>
cannam@89:         public CRC32Checksum() : base() {}
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Initializes a new instance of the CRC32 checksum generator with a specified value
cannam@89:         /// </summary>
cannam@89:         /// <param name="initialValue">The value to set the current checksum to</param>
cannam@89:         public CRC32Checksum(uint initialValue) : base(initialValue) {}
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Updates the current checksum with part of an array of bytes
cannam@89:         /// </summary>
cannam@89:         /// <param name="data">The data to update the checksum with</param>
cannam@89:         /// <param name="offset">Where in <c>data</c> to start updating</param>
cannam@89:         /// <param name="count">The number of bytes from <c>data</c> to use</param>
cannam@89:         /// <exception cref="ArgumentException">The sum of offset and count is larger than the length of <c>data</c></exception>
cannam@89:         /// <exception cref="NullReferenceException"><c>data</c> is a null reference</exception>
cannam@89:         /// <exception cref="ArgumentOutOfRangeException">Offset or count is negative.</exception>
cannam@89:         public override void Update(byte[] data, int offset, int count)
cannam@89:         {
cannam@89:             if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
cannam@89:             if ((offset+count) > data.Length) throw new ArgumentException();
cannam@89:             GCHandle hData = GCHandle.Alloc(data, GCHandleType.Pinned);
cannam@89:             try
cannam@89:             {
cannam@89:                 _current = crc32(_current, hData.AddrOfPinnedObject().ToInt32()+offset, (uint)count);
cannam@89:             }
cannam@89:             finally
cannam@89:             {
cannam@89:                 hData.Free();
cannam@89:             }
cannam@89:         }
cannam@89: 
cannam@89:     }
cannam@89:     #endregion
cannam@89: 
cannam@89:     #region Adler
cannam@89:     /// <summary>
cannam@89:     /// Implements a checksum generator that computes the Adler checksum on data
cannam@89:     /// </summary>
cannam@89:     public sealed class AdlerChecksum : ChecksumGeneratorBase
cannam@89:     {
cannam@89:         #region DLL imports
cannam@89: 
cannam@89:         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
cannam@89:         private static extern uint adler32(uint adler, int data, uint length);
cannam@89: 
cannam@89:         #endregion
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Initializes a new instance of the Adler checksum generator
cannam@89:         /// </summary>
cannam@89:         public AdlerChecksum() : base() {}
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Initializes a new instance of the Adler checksum generator with a specified value
cannam@89:         /// </summary>
cannam@89:         /// <param name="initialValue">The value to set the current checksum to</param>
cannam@89:         public AdlerChecksum(uint initialValue) : base(initialValue) {}
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Updates the current checksum with part of an array of bytes
cannam@89:         /// </summary>
cannam@89:         /// <param name="data">The data to update the checksum with</param>
cannam@89:         /// <param name="offset">Where in <c>data</c> to start updating</param>
cannam@89:         /// <param name="count">The number of bytes from <c>data</c> to use</param>
cannam@89:         /// <exception cref="ArgumentException">The sum of offset and count is larger than the length of <c>data</c></exception>
cannam@89:         /// <exception cref="NullReferenceException"><c>data</c> is a null reference</exception>
cannam@89:         /// <exception cref="ArgumentOutOfRangeException">Offset or count is negative.</exception>
cannam@89:         public override void Update(byte[] data, int offset, int count)
cannam@89:         {
cannam@89:             if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
cannam@89:             if ((offset+count) > data.Length) throw new ArgumentException();
cannam@89:             GCHandle hData = GCHandle.Alloc(data, GCHandleType.Pinned);
cannam@89:             try
cannam@89:             {
cannam@89:                 _current = adler32(_current, hData.AddrOfPinnedObject().ToInt32()+offset, (uint)count);
cannam@89:             }
cannam@89:             finally
cannam@89:             {
cannam@89:                 hData.Free();
cannam@89:             }
cannam@89:         }
cannam@89: 
cannam@89:     }
cannam@89:     #endregion
cannam@89: 
cannam@89: }