107 lines
3.9 KiB
C#
107 lines
3.9 KiB
C#
//
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// © Copyright Henrik Ravn 2004
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//
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// Use, modification and distribution are subject to the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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using System;
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using System.Diagnostics;
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using System.Runtime.InteropServices;
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namespace DotZLib
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{
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/// <summary>
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/// Implements a data compressor, using the deflate algorithm in the ZLib dll
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/// </summary>
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public sealed class Deflater : CodecBase
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{
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#region Dll imports
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[DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl, CharSet=CharSet.Ansi)]
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private static extern int deflateInit_(ref ZStream sz, int level, string vs, int size);
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[DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
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private static extern int deflate(ref ZStream sz, int flush);
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[DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
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private static extern int deflateReset(ref ZStream sz);
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[DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
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private static extern int deflateEnd(ref ZStream sz);
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#endregion
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/// <summary>
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/// Constructs an new instance of the <c>Deflater</c>
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/// </summary>
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/// <param name="level">The compression level to use for this <c>Deflater</c></param>
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public Deflater(CompressLevel level) : base()
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{
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int retval = deflateInit_(ref _ztream, (int)level, Info.Version, Marshal.SizeOf(_ztream));
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if (retval != 0)
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throw new ZLibException(retval, "Could not initialize deflater");
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resetOutput();
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}
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/// <summary>
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/// Adds more data to the codec to be processed.
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/// </summary>
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/// <param name="data">Byte array containing the data to be added to the codec</param>
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/// <param name="offset">The index of the first byte to add from <c>data</c></param>
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/// <param name="count">The number of bytes to add</param>
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/// <remarks>Adding data may, or may not, raise the <c>DataAvailable</c> event</remarks>
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public override void Add(byte[] data, int offset, int count)
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{
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if (data == null) throw new ArgumentNullException();
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if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
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if ((offset+count) > data.Length) throw new ArgumentException();
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int total = count;
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int inputIndex = offset;
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int err = 0;
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while (err >= 0 && inputIndex < total)
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{
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copyInput(data, inputIndex, Math.Min(total - inputIndex, kBufferSize));
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while (err >= 0 && _ztream.avail_in > 0)
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{
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err = deflate(ref _ztream, (int)FlushTypes.None);
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if (err == 0)
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while (_ztream.avail_out == 0)
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{
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OnDataAvailable();
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err = deflate(ref _ztream, (int)FlushTypes.None);
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}
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inputIndex += (int)_ztream.total_in;
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}
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}
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setChecksum( _ztream.adler );
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}
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/// <summary>
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/// Finishes up any pending data that needs to be processed and handled.
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/// </summary>
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public override void Finish()
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{
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int err;
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do
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{
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err = deflate(ref _ztream, (int)FlushTypes.Finish);
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OnDataAvailable();
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}
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while (err == 0);
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setChecksum( _ztream.adler );
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deflateReset(ref _ztream);
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resetOutput();
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}
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/// <summary>
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/// Closes the internal zlib deflate stream
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/// </summary>
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protected override void CleanUp() { deflateEnd(ref _ztream); }
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}
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}
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