/Utilities/Compression/Deflaters/DeflaterConstants.cs

// Based on Mike Krueger's SharpZipLib, Copyright (C) 2001 (GNU license).

// Authors of the original java version: Jochen Hoenicke, John Leuner

// See http://www.ISeeSharpCode.com for more information.



using System;



namespace Delta.Utilities.Compression.Deflaters

{

	/// <summary>

	/// This class contains constants used for deflation.

	/// </summary>

	public class DeflaterConstants

	{

		#region Constants

		/// <summary>

		/// Written to Zip file to identify a stored block

		/// </summary>

		public const int StoredBlock = 0;



		/// <summary>

		/// Identifies static tree in Zip file

		/// </summary>

		public const int StaticTrees = 1;



		/// <summary>

		/// Identifies dynamic tree in Zip file

		/// </summary>

		public const int DynamicTrees = 2;



		/// <summary>

		/// Header flag indicating a preset dictionary for deflation

		/// </summary>

		public const int PresetDictionary = 0x20;



		/// <summary>

		/// Sets internal buffer sizes for Huffman encoding

		/// </summary>

		public const int DefaultMemoryLevel = 8;



		/// <summary>

		/// Max match. Internal compression engine constant

		/// </summary>		

		public const int MaxMatch = 258;



		/// <summary>

		/// Min match. Internal compression engine constant

		/// </summary>		

		public const int MinMatch = 3;



		/// <summary>

		/// Max WBits for WSize. Internal compression engine constant

		/// </summary>		

		public const int MaxWBits = 15;



		/// <summary>

		/// WSize. Internal compression engine constant

		/// </summary>		

		public const int WSize = 1 << MaxWBits;



		/// <summary>

		/// WMask. Internal compression engine constant

		/// </summary>		

		public const int WMask = WSize - 1;



		/// <summary>

		/// Hash bits. Internal compression engine constant

		/// </summary>		

		public const int HashBits = DefaultMemoryLevel + 7;



		/// <summary>

		/// Hash size. Internal compression engine constant

		/// </summary>		

		public const int HashSize = 1 << HashBits;



		/// <summary>

		/// Hash mask. Internal compression engine constant

		/// </summary>		

		public const int HashMask = HashSize - 1;



		/// <summary>

		/// Hash shift. Internal compression engine constant

		/// </summary>		

		public const int HashShift = (HashBits + MinMatch - 1) / MinMatch;



		/// <summary>

		/// Min look ahead. Internal compression engine constant

		/// </summary>		

		public const int MinLookAhead = MaxMatch + MinMatch + 1;



		/// <summary>

		/// Max distance. Internal compression engine constant

		/// </summary>		

		public const int MaxDistance = WSize - MinLookAhead;



		/// <summary>

		/// Pending buffer size. Internal compression engine constant

		/// </summary>		

		public const int PendingBufferSize = 1 << (DefaultMemoryLevel + 8);



		/// <summary>

		/// Compression deflate stored. Internal compression engine constant

		/// </summary>		

		public const int CompressionDeflateStored = 0;



		/// <summary>

		/// Compression deflate fast. Internal compression engine constant

		/// </summary>		

		public const int CompressionDeflateFast = 1;



		/// <summary>

		/// Compression deflate slow. Internal compression engine constant

		/// </summary>		

		public const int CompressionDeflateSlow = 2;

		#endregion



		#region MaxBlockSize (Static)

		/// <summary>

		/// Max block size. Internal compression engine constant

		/// </summary>		

		public static int MaxBlockSize = Math.Min(65535, PendingBufferSize - 5);

		#endregion



		#region GoodLength (Static)

		/// <summary>

		/// Good length. Internal compression engine constant

		/// </summary>		

		public static int[] GoodLength = {

			0, 4, 4, 4, 4, 8, 8, 8, 32, 32

		};

		#endregion



		#region MaxLazy (Static)

		/// <summary>

		/// Max lazy. Internal compression engine constant

		/// </summary>		

		public static int[] MaxLazy = {

			0, 4, 5, 6, 4, 16, 16, 32, 128, 258

		};

		#endregion



		#region NiceLength (Static)

		/// <summary>

		/// Nice length. Internal compression engine constant

		/// </summary>		

		public static int[] NiceLength =

			{

				0, 8, 16, 32, 16, 32, 128, 128, 258, 258

			};

		#endregion



		#region MaxChain (Static)

		/// <summary>

		/// Max chain. Internal compression engine constant

		/// </summary>		

		public static int[] MaxChain =

			{

				0, 4, 8, 32, 16, 32, 128, 256, 1024, 4096

			};

		#endregion



		#region CompressionFunction (Static)

		/// <summary>

		/// Compression function. Internal compression engine constant

		/// </summary>		

		public static int[] CompressionFunction =

			{

				0, 1, 1, 1, 1, 2, 2, 2, 2, 2

			};

		#endregion

	}

}