irc/TechBot/Compression/Checksums/StrangeCRC.cs

   1 // StrangeCRC.cs - computes a crc used in the bziplib ... I don't think that
   2 //                 this is the 'standard' crc, please correct me, if I'm wrong
   3 // Copyright (C) 2001 Mike Krueger
   4 //
   5 // This file was translated from java, it was part of the GNU Classpath
   6 // Copyright (C) 1999, 2000, 2001 Free Software Foundation, Inc.
   7 //
   8 // This program is free software; you can redistribute it and/or
   9 // modify it under the terms of the GNU General Public License
  10 // as published by the Free Software Foundation; either version 2
  11 // of the License, or (at your option) any later version.
  12 //
  13 // This program is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 // GNU General Public License for more details.
  17 //
  18 // You should have received a copy of the GNU General Public License
  19 // along with this program; if not, write to the Free Software
  20 // Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  21 //
  22 // Linking this library statically or dynamically with other modules is
  23 // making a combined work based on this library.  Thus, the terms and
  24 // conditions of the GNU General Public License cover the whole
  25 // combination.
  26 //
  27 // As a special exception, the copyright holders of this library give you
  28 // permission to link this library with independent modules to produce an
  29 // executable, regardless of the license terms of these independent
  30 // modules, and to copy and distribute the resulting executable under
  31 // terms of your choice, provided that you also meet, for each linked
  32 // independent module, the terms and conditions of the license of that
  33 // module.  An independent module is a module which is not derived from
  34 // or based on this library.  If you modify this library, you may extend
  35 // this exception to your version of the library, but you are not
  36 // obligated to do so.  If you do not wish to do so, delete this
  37 // exception statement from your version.
  38
  39 using System;
  40
  41 namespace ICSharpCode.SharpZipLib.Checksums
  42 {
  43
  44         public class StrangeCRC : IChecksum
  45         {
  46                 readonly static uint[] crc32Table = {
  47                         0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9,
  48                         0x130476dc, 0x17c56b6b, 0x1a864db2, 0x1e475005,
  49                         0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61,
  50                         0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
  51                         0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9,
  52                         0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
  53                         0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011,
  54                         0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd,
  55                         0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
  56                         0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5,
  57                         0xbe2b5b58, 0xbaea46ef, 0xb7a96036, 0xb3687d81,
  58                         0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
  59                         0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49,
  60                         0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
  61                         0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1,
  62                         0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d,
  63                         0x34867077, 0x30476dc0, 0x3d044b19, 0x39c556ae,
  64                         0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
  65                         0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16,
  66                         0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca,
  67                         0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde,
  68                         0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02,
  69                         0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066,
  70                         0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
  71                         0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e,
  72                         0xbfa1b04b, 0xbb60adfc, 0xb6238b25, 0xb2e29692,
  73                         0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6,
  74                         0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a,
  75                         0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e,
  76                         0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
  77                         0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686,
  78                         0xd5b88683, 0xd1799b34, 0xdc3abded, 0xd8fba05a,
  79                         0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637,
  80                         0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
  81                         0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f,
  82                         0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
  83                         0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47,
  84                         0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b,
  85                         0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
  86                         0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623,
  87                         0xf12f560e, 0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7,
  88                         0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
  89                         0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f,
  90                         0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
  91                         0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7,
  92                         0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b,
  93                         0x9b3660c6, 0x9ff77d71, 0x92b45ba8, 0x9675461f,
  94                         0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
  95                         0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640,
  96                         0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c,
  97                         0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8,
  98                         0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24,
  99                         0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30,
 100                         0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
 101                         0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088,
 102                         0x2497d08d, 0x2056cd3a, 0x2d15ebe3, 0x29d4f654,
 103                         0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0,
 104                         0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c,
 105                         0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18,
 106                         0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
 107                         0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0,
 108                         0x9abc8bd5, 0x9e7d9662, 0x933eb0bb, 0x97ffad0c,
 109                         0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668,
 110                         0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4
 111                 };
 112                 int globalCrc;
 113
 114                 public StrangeCRC()
 115                 {
 116                         Reset();
 117                 }
 118
 119                 public void Reset()
 120                 {
 121                         globalCrc = -1;
 122                 }
 123
 124                 public long Value {
 125                         get {
 126                                 return ~globalCrc;
 127                         }
 128                 }
 129
 130                 public void Update(int inCh)
 131                 {
 132                         int temp = (globalCrc >> 24) ^ inCh;
 133                         if (temp < 0) {
 134                                 temp = 256 + temp;
 135                         }
 136                         globalCrc = (int)((globalCrc << 8) ^ crc32Table[temp]);
 137                 }
 138
 139                 public void Update(byte[] buf)
 140                 {
 141                         Update(buf, 0, buf.Length);
 142                 }
 143
 144                 public void Update(byte[] buf, int off, int len)
 145                 {
 146                         if (buf == null) {
 147                                 throw new ArgumentNullException("buf");
 148                         }
 149
 150                         if (off < 0 || len < 0 || off + len > buf.Length) {
 151                                 throw new ArgumentOutOfRangeException();
 152                         }
 153
 154                         for (int i = 0; i < len; ++i) {
 155                                 Update(buf[off++]);
 156                         }
 157                 }
 158         }
 159 }