12905761471

Committed 22 Jan 2025 10:03AM UTC coverage: 2.0% (-74.0%) from 75.963%

Build # 12905761471

Build Type

push

github

Committed by

DomCR

Commit Message

version 1.0.6

Run Details

104 of 7676 branches covered (1.35%)

Branch coverage included in aggregate %.

590 of 27024 relevant lines covered (2.18%)

5.13 hits per line

Source File
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0.0

/src/ACadSharp/IO/DWG/CRC8StreamHandler.cs

﻿using System.IO;

namespace ACadSharp.IO.DWG
{
        /// <summary>
        /// The DWG file format uses a modification of a standard cyclic redundancy check as an error detecting mechanism. <br/>
        /// This class checks the integrity of the file using this check.
        /// </summary>
        /// <remarks>
        /// This method is used extensively in pre-R13 files, but seems only to be used in the header for R13 and beyond.
        /// </remarks>
        internal class CRC8StreamHandler : Stream
        {
                public override bool CanRead => this._stream.CanRead;

                public override bool CanSeek => this._stream.CanSeek;

                public override bool CanWrite => this._stream.CanWrite;

                public override long Length => this._stream.Length;

                public override long Position
                {
                        get => this._stream.Position;
                        set => this._stream.Position = value;
                }

                public ushort Seed { get; private set; }

                private Stream _stream;

                public CRC8StreamHandler(Stream stream, ushort seed)
                {
                        this._stream = stream;
                        this.Seed = seed;
                }

                public override int Read(byte[] buffer, int offset, int count)
                {
                        int nbytes = this._stream.Read(buffer, offset, count);
                        int length = offset + count;

                        for (int index = offset; index < length; ++index)
                                this.Seed = decode(this.Seed, buffer[index]);

                        return nbytes;
                }

                public override void Flush() => this._stream.Flush();

                public override long Seek(long offset, SeekOrigin origin) => this._stream.Seek(offset, origin);

                public override void SetLength(long value) => this._stream.SetLength(value);

                public override void Write(byte[] buffer, int offset, int count)
                {
                        int length = offset + count;

                        for (int index = offset; index < length; ++index)
                                this.Seed = decode(this.Seed, buffer[index]);

                        this._stream.Write(buffer, offset, count);
                }

                public static ushort GetCRCValue(ushort seed, byte[] buffer, long startPos, long endPos)
                {
                        ushort currValue = seed;
                        int index = (int)startPos;

                        while (endPos-- > 0)
                        {
                                currValue = CRC8StreamHandler.decode(currValue, buffer[index]);
                                index++;
                        }

                        return currValue;
                }

                private static ushort decode(ushort key, byte value)
                {
                        int index = value ^ (byte)key;
                        key = (ushort)((uint)key >> 8 ^ CRC.CrcTable[index]);
                        return key;
                }
        }
}

1	using System.IO;
2
3	namespace ACadSharp.IO.DWG
4	{
5	/// <summary>
6	/// The DWG file format uses a modification of a standard cyclic redundancy check as an error detecting mechanism. <br/>
7	/// This class checks the integrity of the file using this check.
8	/// </summary>
9	/// <remarks>
10	/// This method is used extensively in pre-R13 files, but seems only to be used in the header for R13 and beyond.
11	/// </remarks>
12	internal class CRC8StreamHandler : Stream
13	{
14	public override bool CanRead => this._stream.CanRead;	×
15
16	public override bool CanSeek => this._stream.CanSeek;	×
17
18	public override bool CanWrite => this._stream.CanWrite;	×
19
20	public override long Length => this._stream.Length;	×
21
22	public override long Position
23	{
24	get => this._stream.Position;	×
25	set => this._stream.Position = value;	×
26	}
27
28	public ushort Seed { get; private set; }	×
29
30	private Stream _stream;
31
32	public CRC8StreamHandler(Stream stream, ushort seed)	×
33	{	×
34	this._stream = stream;	×
35	this.Seed = seed;	×
36	}	×
37
38	public override int Read(byte[] buffer, int offset, int count)
39	{	×
40	int nbytes = this._stream.Read(buffer, offset, count);	×
41	int length = offset + count;	×
42
43	for (int index = offset; index < length; ++index)	×
44	this.Seed = decode(this.Seed, buffer[index]);	×
45
46	return nbytes;	×
47	}	×
48
49	public override void Flush() => this._stream.Flush();	×
50
51	public override long Seek(long offset, SeekOrigin origin) => this._stream.Seek(offset, origin);	×
52
53	public override void SetLength(long value) => this._stream.SetLength(value);	×
54
55	public override void Write(byte[] buffer, int offset, int count)
56	{	×
57	int length = offset + count;	×
58
59	for (int index = offset; index < length; ++index)	×
60	this.Seed = decode(this.Seed, buffer[index]);	×
61
62	this._stream.Write(buffer, offset, count);	×
63	}	×
64
65	public static ushort GetCRCValue(ushort seed, byte[] buffer, long startPos, long endPos)
66	{	×
67	ushort currValue = seed;	×
68	int index = (int)startPos;	×
69
70	while (endPos-- > 0)	×
71	{	×
72	currValue = CRC8StreamHandler.decode(currValue, buffer[index]);	×
73	index++;	×
74	}	×
75
76	return currValue;	×
77	}	×
78
79	private static ushort decode(ushort key, byte value)
80	{	×
81	int index = value ^ (byte)key;	×
82	key = (ushort)((uint)key >> 8 ^ CRC.CrcTable[index]);	×
83	return key;	×
84	}	×
85	}
86	}

DomCR / ACadSharp / 12905761471

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