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1 | | -using System; |
2 | | - |
3 | 1 | namespace ICSharpCode.SharpZipLib.Checksum |
4 | 2 | { |
5 | 3 | /// <summary> |
6 | 4 | /// CRC-32 with unreversed data and reversed output |
7 | 5 | /// </summary> |
8 | 6 | /// <remarks> |
9 | | - /// Generate a table for a byte-wise 32-bit CRC calculation on the polynomial: |
10 | | - /// x^32+x^26+x^23+x^22+x^16+x^12+x^11+x^10+x^8+x^7+x^5+x^4+x^2+x^1+x^0. |
11 | | - /// |
12 | | - /// Polynomials over GF(2) are represented in binary, one bit per coefficient, |
13 | | - /// with the lowest powers in the most significant bit. Then adding polynomials |
14 | | - /// is just exclusive-or, and multiplying a polynomial by x is a right shift by |
15 | | - /// one. If we call the above polynomial p, and represent a byte as the |
16 | | - /// polynomial q, also with the lowest power in the most significant bit (so the |
17 | | - /// byte 0xb1 is the polynomial x^7+x^3+x+1), then the CRC is (q*x^32) mod p, |
18 | | - /// where a mod b means the remainder after dividing a by b. |
19 | | - /// |
20 | | - /// This calculation is done using the shift-register method of multiplying and |
21 | | - /// taking the remainder. The register is initialized to zero, and for each |
22 | | - /// incoming bit, x^32 is added mod p to the register if the bit is a one (where |
23 | | - /// x^32 mod p is p+x^32 = x^26+...+1), and the register is multiplied mod p by |
24 | | - /// x (which is shifting right by one and adding x^32 mod p if the bit shifted |
25 | | - /// out is a one). We start with the highest power (least significant bit) of |
26 | | - /// q and repeat for all eight bits of q. |
27 | | - /// |
28 | | - /// The table is simply the CRC of all possible eight bit values. This is all |
29 | | - /// the information needed to generate CRC's on data a byte at a time for all |
30 | | - /// combinations of CRC register values and incoming bytes. |
| 7 | + /// Using Force.CRC32 System. Thanks force-net. |
31 | 8 | /// </remarks> |
32 | | - public sealed class BZip2Crc : IChecksum |
| 9 | + public sealed class BZip2Crc : Crc32Base |
33 | 10 | { |
34 | | - #region Instance Fields |
35 | | - |
36 | | - private const uint crcInit = 0xFFFFFFFF; |
37 | | - //const uint crcXor = 0x00000000; |
38 | | - |
39 | | - private static readonly uint[] crcTable = { |
40 | | - 0X00000000, 0X04C11DB7, 0X09823B6E, 0X0D4326D9, |
41 | | - 0X130476DC, 0X17C56B6B, 0X1A864DB2, 0X1E475005, |
42 | | - 0X2608EDB8, 0X22C9F00F, 0X2F8AD6D6, 0X2B4BCB61, |
43 | | - 0X350C9B64, 0X31CD86D3, 0X3C8EA00A, 0X384FBDBD, |
44 | | - 0X4C11DB70, 0X48D0C6C7, 0X4593E01E, 0X4152FDA9, |
45 | | - 0X5F15ADAC, 0X5BD4B01B, 0X569796C2, 0X52568B75, |
46 | | - 0X6A1936C8, 0X6ED82B7F, 0X639B0DA6, 0X675A1011, |
47 | | - 0X791D4014, 0X7DDC5DA3, 0X709F7B7A, 0X745E66CD, |
48 | | - 0X9823B6E0, 0X9CE2AB57, 0X91A18D8E, 0X95609039, |
49 | | - 0X8B27C03C, 0X8FE6DD8B, 0X82A5FB52, 0X8664E6E5, |
50 | | - 0XBE2B5B58, 0XBAEA46EF, 0XB7A96036, 0XB3687D81, |
51 | | - 0XAD2F2D84, 0XA9EE3033, 0XA4AD16EA, 0XA06C0B5D, |
52 | | - 0XD4326D90, 0XD0F37027, 0XDDB056FE, 0XD9714B49, |
53 | | - 0XC7361B4C, 0XC3F706FB, 0XCEB42022, 0XCA753D95, |
54 | | - 0XF23A8028, 0XF6FB9D9F, 0XFBB8BB46, 0XFF79A6F1, |
55 | | - 0XE13EF6F4, 0XE5FFEB43, 0XE8BCCD9A, 0XEC7DD02D, |
56 | | - 0X34867077, 0X30476DC0, 0X3D044B19, 0X39C556AE, |
57 | | - 0X278206AB, 0X23431B1C, 0X2E003DC5, 0X2AC12072, |
58 | | - 0X128E9DCF, 0X164F8078, 0X1B0CA6A1, 0X1FCDBB16, |
59 | | - 0X018AEB13, 0X054BF6A4, 0X0808D07D, 0X0CC9CDCA, |
60 | | - 0X7897AB07, 0X7C56B6B0, 0X71159069, 0X75D48DDE, |
61 | | - 0X6B93DDDB, 0X6F52C06C, 0X6211E6B5, 0X66D0FB02, |
62 | | - 0X5E9F46BF, 0X5A5E5B08, 0X571D7DD1, 0X53DC6066, |
63 | | - 0X4D9B3063, 0X495A2DD4, 0X44190B0D, 0X40D816BA, |
64 | | - 0XACA5C697, 0XA864DB20, 0XA527FDF9, 0XA1E6E04E, |
65 | | - 0XBFA1B04B, 0XBB60ADFC, 0XB6238B25, 0XB2E29692, |
66 | | - 0X8AAD2B2F, 0X8E6C3698, 0X832F1041, 0X87EE0DF6, |
67 | | - 0X99A95DF3, 0X9D684044, 0X902B669D, 0X94EA7B2A, |
68 | | - 0XE0B41DE7, 0XE4750050, 0XE9362689, 0XEDF73B3E, |
69 | | - 0XF3B06B3B, 0XF771768C, 0XFA325055, 0XFEF34DE2, |
70 | | - 0XC6BCF05F, 0XC27DEDE8, 0XCF3ECB31, 0XCBFFD686, |
71 | | - 0XD5B88683, 0XD1799B34, 0XDC3ABDED, 0XD8FBA05A, |
72 | | - 0X690CE0EE, 0X6DCDFD59, 0X608EDB80, 0X644FC637, |
73 | | - 0X7A089632, 0X7EC98B85, 0X738AAD5C, 0X774BB0EB, |
74 | | - 0X4F040D56, 0X4BC510E1, 0X46863638, 0X42472B8F, |
75 | | - 0X5C007B8A, 0X58C1663D, 0X558240E4, 0X51435D53, |
76 | | - 0X251D3B9E, 0X21DC2629, 0X2C9F00F0, 0X285E1D47, |
77 | | - 0X36194D42, 0X32D850F5, 0X3F9B762C, 0X3B5A6B9B, |
78 | | - 0X0315D626, 0X07D4CB91, 0X0A97ED48, 0X0E56F0FF, |
79 | | - 0X1011A0FA, 0X14D0BD4D, 0X19939B94, 0X1D528623, |
80 | | - 0XF12F560E, 0XF5EE4BB9, 0XF8AD6D60, 0XFC6C70D7, |
81 | | - 0XE22B20D2, 0XE6EA3D65, 0XEBA91BBC, 0XEF68060B, |
82 | | - 0XD727BBB6, 0XD3E6A601, 0XDEA580D8, 0XDA649D6F, |
83 | | - 0XC423CD6A, 0XC0E2D0DD, 0XCDA1F604, 0XC960EBB3, |
84 | | - 0XBD3E8D7E, 0XB9FF90C9, 0XB4BCB610, 0XB07DABA7, |
85 | | - 0XAE3AFBA2, 0XAAFBE615, 0XA7B8C0CC, 0XA379DD7B, |
86 | | - 0X9B3660C6, 0X9FF77D71, 0X92B45BA8, 0X9675461F, |
87 | | - 0X8832161A, 0X8CF30BAD, 0X81B02D74, 0X857130C3, |
88 | | - 0X5D8A9099, 0X594B8D2E, 0X5408ABF7, 0X50C9B640, |
89 | | - 0X4E8EE645, 0X4A4FFBF2, 0X470CDD2B, 0X43CDC09C, |
90 | | - 0X7B827D21, 0X7F436096, 0X7200464F, 0X76C15BF8, |
91 | | - 0X68860BFD, 0X6C47164A, 0X61043093, 0X65C52D24, |
92 | | - 0X119B4BE9, 0X155A565E, 0X18197087, 0X1CD86D30, |
93 | | - 0X029F3D35, 0X065E2082, 0X0B1D065B, 0X0FDC1BEC, |
94 | | - 0X3793A651, 0X3352BBE6, 0X3E119D3F, 0X3AD08088, |
95 | | - 0X2497D08D, 0X2056CD3A, 0X2D15EBE3, 0X29D4F654, |
96 | | - 0XC5A92679, 0XC1683BCE, 0XCC2B1D17, 0XC8EA00A0, |
97 | | - 0XD6AD50A5, 0XD26C4D12, 0XDF2F6BCB, 0XDBEE767C, |
98 | | - 0XE3A1CBC1, 0XE760D676, 0XEA23F0AF, 0XEEE2ED18, |
99 | | - 0XF0A5BD1D, 0XF464A0AA, 0XF9278673, 0XFDE69BC4, |
100 | | - 0X89B8FD09, 0X8D79E0BE, 0X803AC667, 0X84FBDBD0, |
101 | | - 0X9ABC8BD5, 0X9E7D9662, 0X933EB0BB, 0X97FFAD0C, |
102 | | - 0XAFB010B1, 0XAB710D06, 0XA6322BDF, 0XA2F33668, |
103 | | - 0XBCB4666D, 0XB8757BDA, 0XB5365D03, 0XB1F740B4 |
104 | | - }; |
105 | | - |
106 | | - /// <summary> |
107 | | - /// The CRC data checksum so far. |
108 | | - /// </summary> |
109 | | - private uint checkValue; |
110 | | - |
111 | | - #endregion Instance Fields |
112 | | - |
113 | | - /// <summary> |
114 | | - /// Initialise a default instance of <see cref="BZip2Crc"></see> |
115 | | - /// </summary> |
116 | | - public BZip2Crc() |
117 | | - { |
118 | | - Reset(); |
119 | | - } |
120 | | - |
121 | | - /// <summary> |
122 | | - /// Resets the CRC data checksum as if no update was ever called. |
123 | | - /// </summary> |
124 | | - public void Reset() |
125 | | - { |
126 | | - checkValue = crcInit; |
127 | | - } |
| 11 | + private static readonly NormalCrc32Proxy proxy = new NormalCrc32Proxy(); |
| 12 | + internal override Crc32ProxyBase Proxy => proxy; |
128 | 13 |
|
129 | | - /// <summary> |
130 | | - /// Returns the CRC data checksum computed so far. |
131 | | - /// </summary> |
132 | | - /// <remarks>Reversed Out = true</remarks> |
133 | | - public long Value |
| 14 | + internal static uint ComputeCrc32(uint oldCrc, byte bval) |
134 | 15 | { |
135 | | - get |
136 | | - { |
137 | | - // Technically, the output should be: |
138 | | - //return (long)(~checkValue ^ crcXor); |
139 | | - // but x ^ 0 = x, so there is no point in adding |
140 | | - // the XOR operation |
141 | | - return ~checkValue; |
142 | | - } |
143 | | - } |
144 | | - |
145 | | - /// <summary> |
146 | | - /// Updates the checksum with the int bval. |
147 | | - /// </summary> |
148 | | - /// <param name = "bval"> |
149 | | - /// the byte is taken as the lower 8 bits of bval |
150 | | - /// </param> |
151 | | - /// <remarks>Reversed Data = false</remarks> |
152 | | - public void Update(int bval) |
153 | | - { |
154 | | - checkValue = unchecked(crcTable[(byte)(((checkValue >> 24) & 0xFF) ^ bval)] ^ (checkValue << 8)); |
155 | | - } |
156 | | - |
157 | | - /// <summary> |
158 | | - /// Updates the CRC data checksum with the bytes taken from |
159 | | - /// a block of data. |
160 | | - /// </summary> |
161 | | - /// <param name="buffer">Contains the data to update the CRC with.</param> |
162 | | - public void Update(byte[] buffer) |
163 | | - { |
164 | | - if (buffer == null) |
165 | | - { |
166 | | - throw new ArgumentNullException(nameof(buffer)); |
167 | | - } |
168 | | - |
169 | | - Update(new ArraySegment<byte>(buffer, 0, buffer.Length)); |
170 | | - } |
171 | | - |
172 | | - /// <summary> |
173 | | - /// Update CRC data checksum based on a portion of a block of data |
174 | | - /// </summary> |
175 | | - /// <param name = "segment"> |
176 | | - /// The chunk of data to add |
177 | | - /// </param> |
178 | | - public void Update(ArraySegment<byte> segment) |
179 | | - { |
180 | | - var count = segment.Count; |
181 | | - var offset = segment.Offset; |
182 | | - |
183 | | - while (--count >= 0) |
184 | | - Update(segment.Array[offset++]); |
| 16 | + return ~proxy.Append(~oldCrc, new[] { bval }, 0, 1); |
185 | 17 | } |
186 | 18 | } |
187 | 19 | } |
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