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C#: Calcule de CRC

Exemple,d'utilisation,de,'PermissionSet'
{filelink=17832}

// StrangeCRC.cs - computes a crc used in the bziplib
//
// Copyright (C) 2001 Mike Krueger
//
// This file was translated from java, it was part of the GNU Classpath
// Copyright (C) 1999, 2000, 2001 Free Software Foundation, Inc.
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
//
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent
// modules, and to copy and distribute the resulting executable under
// terms of your choice, provided that you also meet, for each linked
// independent module, the terms and conditions of the license of that
// module.  An independent module is a module which is not derived from
// or based on this library.  If you modify this library, you may extend
// this exception to your version of the library, but you are not
// obligated to do so.  If you do not wish to do so, delete this
// exception statement from your version.
 
using System;
 
namespace MesExemples.Securités
{
 
// Algerithme Bzip2 checksum
 
  public class StrangeCRC
  {
    readonly static uint[] tableCRC32 = {
      0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9,
      0x130476dc, 0x17c56b6b, 0x1a864db2, 0x1e475005,
      0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61,
      0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
      0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9,
      0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
      0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011,
      0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd,
      0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
      0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5,
      0xbe2b5b58, 0xbaea46ef, 0xb7a96036, 0xb3687d81,
      0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
      0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49,
      0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
      0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1,
      0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d,
      0x34867077, 0x30476dc0, 0x3d044b19, 0x39c556ae,
      0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
      0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16,
      0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca,
      0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde,
      0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02,
      0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066,
      0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
      0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e,
      0xbfa1b04b, 0xbb60adfc, 0xb6238b25, 0xb2e29692,
      0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6,
      0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a,
      0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e,
      0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
      0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686,
      0xd5b88683, 0xd1799b34, 0xdc3abded, 0xd8fba05a,
      0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637,
      0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
      0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f,
      0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
      0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47,
      0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b,
      0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
      0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623,
      0xf12f560e, 0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7,
      0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
      0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f,
      0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
      0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7,
      0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b,
      0x9b3660c6, 0x9ff77d71, 0x92b45ba8, 0x9675461f,
      0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
      0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640,
      0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c,
      0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8,
      0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24,
      0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30,
      0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
      0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088,
      0x2497d08d, 0x2056cd3a, 0x2d15ebe3, 0x29d4f654,
      0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0,
      0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c,
      0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18,
      0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
      0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0,
      0x9abc8bd5, 0x9e7d9662, 0x933eb0bb, 0x97ffad0c,
      0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668,
      0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4
    };
 
    int CRCGlobal;
 
	// Initialisation d'une instance par défaut de 'StrangeCRC'
    public StrangeCRC()
    {
      Reset();
    }
 
	// Réinitialisation de l'etat de CRC
    public void Reset()
    {
      CRCGlobal = -1;
    }
 
    ///
<summary>
    /// Get the current Crc value.
    /// </summary>
 
	// Obtenir la valeur courante de CRC
    public long ObtenirValeur
	{
      get {
        return ~CRCGlobal;
      }
    }
 
	//Actualiser la valeur de CRC
    public void ActualiserValeur(int value)
    {
      int temp = (CRCGlobal >> 24) ^ value;
      if (temp < 0) {
        temp = 256 + temp;
      }
      CRCGlobal = unchecked((int)((CRCGlobal << 8) ^ tableCRC32[temp]));
    }
 
	//Actualiser le CRC d'un ensemble des données
    public void ActualiserValeur(byte[] buffer)
    {
      if (buffer == null) {
        throw new ArgumentNullException("buffer");
      }
 
      ActualiserValeur(buffer, 0, buffer.Length);
    }
 
	/* Actualiser le CRC d'une portion de données
	   decalage: index de premier octet à utilisé
	    nombre:   nombre d'octets à utilisé
	*/
    public void ActualiserValeur(byte[] buffer, int decalage, int nombre)
    {
      if (buffer == null) {
        throw new ArgumentNullException("buffer");
      }
 
      if ( decalage < 0 )
      {
       #if NETCF_1_0
        throw new ArgumentOutOfRangeException("décalage");
        #else
        throw new ArgumentOutOfRangeException("décalage", "le décalage n'est peut être inferieur à zero");
       #endif
      }
 
      if ( nombre < 0 )
      {
	#if NETCF_1_0
        throw new ArgumentOutOfRangeException("nombre");
	#else
        throw new ArgumentOutOfRangeException("nombre", "le nombre d'octet n'est peut âtre inferieur à zero");
	#endif
      }
 
      if ( decalage + nombre > buffer.Length )
      {
        throw new ArgumentOutOfRangeException("nombre");
      }
 
      for (int i = 0; i < nombre; ++i) {
        ActualiserValeur(buffer[decalage++]);
      }
    }
  }
}

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