source: rtems/cpukit/zlib/contrib/dotzlib/DotZLib/Deflater.cs @ 959f7df2

4.104.114.84.9
Last change on this file since 959f7df2 was 959f7df2, checked in by Ralf Corsepius <ralf.corsepius@…>, on Oct 28, 2005 at 7:22:42 AM

Import of zlib-1.2.2.2.tar.gz

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File size: 3.9 KB
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1//
2// © Copyright Henrik Ravn 2004
3//
4// Use, modification and distribution are subject to the Boost Software License, Version 1.0.
5// (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6//
7
8using System;
9using System.Diagnostics;
10using System.Runtime.InteropServices;
11
12namespace DotZLib
13{
14
15    /// <summary>
16    /// Implements a data compressor, using the deflate algorithm in the ZLib dll
17    /// </summary>
18        public sealed class Deflater : CodecBase
19        {
20        #region Dll imports
21        [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl, CharSet=CharSet.Ansi)]
22        private static extern int deflateInit_(ref ZStream sz, int level, string vs, int size);
23
24        [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
25        private static extern int deflate(ref ZStream sz, int flush);
26
27        [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
28        private static extern int deflateReset(ref ZStream sz);
29
30        [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
31        private static extern int deflateEnd(ref ZStream sz);
32        #endregion
33
34        /// <summary>
35        /// Constructs an new instance of the <c>Deflater</c>
36        /// </summary>
37        /// <param name="level">The compression level to use for this <c>Deflater</c></param>
38                public Deflater(CompressLevel level) : base()
39                {
40            int retval = deflateInit_(ref _ztream, (int)level, Info.Version, Marshal.SizeOf(_ztream));
41            if (retval != 0)
42                throw new ZLibException(retval, "Could not initialize deflater");
43
44            resetOutput();
45                }
46
47        /// <summary>
48        /// Adds more data to the codec to be processed.
49        /// </summary>
50        /// <param name="data">Byte array containing the data to be added to the codec</param>
51        /// <param name="offset">The index of the first byte to add from <c>data</c></param>
52        /// <param name="count">The number of bytes to add</param>
53        /// <remarks>Adding data may, or may not, raise the <c>DataAvailable</c> event</remarks>
54        public override void Add(byte[] data, int offset, int count)
55        {
56            if (data == null) throw new ArgumentNullException();
57            if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
58            if ((offset+count) > data.Length) throw new ArgumentException();
59           
60            int total = count;
61            int inputIndex = offset;
62            int err = 0;
63
64            while (err >= 0 && inputIndex < total)
65            {
66                copyInput(data, inputIndex, Math.Min(total - inputIndex, kBufferSize));
67                while (err >= 0 && _ztream.avail_in > 0)
68                {
69                    err = deflate(ref _ztream, (int)FlushTypes.None);
70                    if (err == 0)
71                        while (_ztream.avail_out == 0)
72                        {
73                            OnDataAvailable();
74                            err = deflate(ref _ztream, (int)FlushTypes.None);
75                        }
76                    inputIndex += (int)_ztream.total_in;
77                }
78            }
79            setChecksum( _ztream.adler );
80        }
81
82
83        /// <summary>
84        /// Finishes up any pending data that needs to be processed and handled.
85        /// </summary>
86        public override void Finish()
87        {
88            int err;
89            do 
90            {
91                err = deflate(ref _ztream, (int)FlushTypes.Finish);
92                OnDataAvailable();
93            }
94            while (err == 0);
95            setChecksum( _ztream.adler );
96            deflateReset(ref _ztream);
97            resetOutput();
98        }
99
100        /// <summary>
101        /// Closes the internal zlib deflate stream
102        /// </summary>
103        protected override void CleanUp() { deflateEnd(ref _ztream); }
104
105    }
106}
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