CRC16 and CRC32 in C#

/***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Initial Developer of the CRC Code is:
 * Thomas Kejser
 * 
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
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 * decision by deleting the provisions above and replace them with the notice
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 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
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 * ***** END LICENSE BLOCK ***** */
using System;
using System.Data;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using Microsoft.SqlServer.Server;

public partial class UserDefinedFunctions
{

  #region constants for CRC32
  const UInt32 FinalCRC32_XOR = 0xFFFFFFFF;
  const UInt32 InitialReminder32 = 0xFFFFFFFF;
  const UInt32 Polynomial32 = 0xEDB88320;


  private static readonly UInt32[] CRCTable32 = {
         0x00000000,0x77073096,0xee0e612c,0x990951ba
        ,0x076dc419,0x706af48f,0xe963a535,0x9e6495a3
        ,0x0edb8832,0x79dcb8a4,0xe0d5e91e,0x97d2d988
        ,0x09b64c2b,0x7eb17cbd,0xe7b82d07,0x90bf1d91
        ,0x1db71064,0x6ab020f2,0xf3b97148,0x84be41de
        ,0x1adad47d,0x6ddde4eb,0xf4d4b551,0x83d385c7
        ,0x136c9856,0x646ba8c0,0xfd62f97a,0x8a65c9ec
        ,0x14015c4f,0x63066cd9,0xfa0f3d63,0x8d080df5
        ,0x3b6e20c8,0x4c69105e,0xd56041e4,0xa2677172
        ,0x3c03e4d1,0x4b04d447,0xd20d85fd,0xa50ab56b
        ,0x35b5a8fa,0x42b2986c,0xdbbbc9d6,0xacbcf940
        ,0x32d86ce3,0x45df5c75,0xdcd60dcf,0xabd13d59
        ,0x26d930ac,0x51de003a,0xc8d75180,0xbfd06116
        ,0x21b4f4b5,0x56b3c423,0xcfba9599,0xb8bda50f
        ,0x2802b89e,0x5f058808,0xc60cd9b2,0xb10be924
        ,0x2f6f7c87,0x58684c11,0xc1611dab,0xb6662d3d
        ,0x76dc4190,0x01db7106,0x98d220bc,0xefd5102a
        ,0x71b18589,0x06b6b51f,0x9fbfe4a5,0xe8b8d433
        ,0x7807c9a2,0x0f00f934,0x9609a88e,0xe10e9818
        ,0x7f6a0dbb,0x086d3d2d,0x91646c97,0xe6635c01
        ,0x6b6b51f4,0x1c6c6162,0x856530d8,0xf262004e
        ,0x6c0695ed,0x1b01a57b,0x8208f4c1,0xf50fc457
        ,0x65b0d9c6,0x12b7e950,0x8bbeb8ea,0xfcb9887c
        ,0x62dd1ddf,0x15da2d49,0x8cd37cf3,0xfbd44c65
        ,0x4db26158,0x3ab551ce,0xa3bc0074,0xd4bb30e2
        ,0x4adfa541,0x3dd895d7,0xa4d1c46d,0xd3d6f4fb
        ,0x4369e96a,0x346ed9fc,0xad678846,0xda60b8d0
        ,0x44042d73,0x33031de5,0xaa0a4c5f,0xdd0d7cc9
        ,0x5005713c,0x270241aa,0xbe0b1010,0xc90c2086
        ,0x5768b525,0x206f85b3,0xb966d409,0xce61e49f
        ,0x5edef90e,0x29d9c998,0xb0d09822,0xc7d7a8b4
        ,0x59b33d17,0x2eb40d81,0xb7bd5c3b,0xc0ba6cad
        ,0xedb88320,0x9abfb3b6,0x03b6e20c,0x74b1d29a
        ,0xead54739,0x9dd277af,0x04db2615,0x73dc1683
        ,0xe3630b12,0x94643b84,0x0d6d6a3e,0x7a6a5aa8
        ,0xe40ecf0b,0x9309ff9d,0x0a00ae27,0x7d079eb1
        ,0xf00f9344,0x8708a3d2,0x1e01f268,0x6906c2fe
        ,0xf762575d,0x806567cb,0x196c3671,0x6e6b06e7
        ,0xfed41b76,0x89d32be0,0x10da7a5a,0x67dd4acc
        ,0xf9b9df6f,0x8ebeeff9,0x17b7be43,0x60b08ed5
        ,0xd6d6a3e8,0xa1d1937e,0x38d8c2c4,0x4fdff252
        ,0xd1bb67f1,0xa6bc5767,0x3fb506dd,0x48b2364b
        ,0xd80d2bda,0xaf0a1b4c,0x36034af6,0x41047a60
        ,0xdf60efc3,0xa867df55,0x316e8eef,0x4669be79
        ,0xcb61b38c,0xbc66831a,0x256fd2a0,0x5268e236
        ,0xcc0c7795,0xbb0b4703,0x220216b9,0x5505262f
        ,0xc5ba3bbe,0xb2bd0b28,0x2bb45a92,0x5cb36a04
        ,0xc2d7ffa7,0xb5d0cf31,0x2cd99e8b,0x5bdeae1d
        ,0x9b64c2b0,0xec63f226,0x756aa39c,0x026d930a
        ,0x9c0906a9,0xeb0e363f,0x72076785,0x05005713
        ,0x95bf4a82,0xe2b87a14,0x7bb12bae,0x0cb61b38
        ,0x92d28e9b,0xe5d5be0d,0x7cdcefb7,0x0bdbdf21
        ,0x86d3d2d4,0xf1d4e242,0x68ddb3f8,0x1fda836e
        ,0x81be16cd,0xf6b9265b,0x6fb077e1,0x18b74777
        ,0x88085ae6,0xff0f6a70,0x66063bca,0x11010b5c
        ,0x8f659eff,0xf862ae69,0x616bffd3,0x166ccf45
        ,0xa00ae278,0xd70dd2ee,0x4e048354,0x3903b3c2
        ,0xa7672661,0xd06016f7,0x4969474d,0x3e6e77db
        ,0xaed16a4a,0xd9d65adc,0x40df0b66,0x37d83bf0
        ,0xa9bcae53,0xdebb9ec5,0x47b2cf7f,0x30b5ffe9
        ,0xbdbdf21c,0xcabac28a,0x53b39330,0x24b4a3a6
        ,0xbad03605,0xcdd70693,0x54de5729,0x23d967bf
        ,0xb3667a2e,0xc4614ab8,0x5d681b02,0x2a6f2b94
        ,0xb40bbe37,0xc30c8ea1,0x5a05df1b,0x2d02ef8d
        };
  #endregion

  [Microsoft.SqlServer.Server.SqlFunction(IsDeterministic = true
    , IsPrecise = false, DataAccess = DataAccessKind.None)]
  public static SqlInt32 CRC32_Naive(SqlBinary data)
  {


    Int32 length = (Int32)data.Length;
    if (length == 0)
      return 0;

    UInt32 rem = InitialReminder32;
    for (int i = 0; i < length; i++)
    {
      rem = rem ^ data[i];
      for (int j = 0; j < 8; j++)
      {
        if ((rem & 0x00000001) == 0x00000001)
        {   // if rightmost (least significant) bit is set
          rem = (rem >> 1) ^ Polynomial32; /* Polynomial */
        }
        else
        {
          rem = (rem >> 1);
        }
      }
    }
    /* Interface back to SQL server */
    unchecked
    {
      return (SqlInt32)(Int32)(rem ^ FinalCRC32_XOR);
    }
  }

  [Microsoft.SqlServer.Server.SqlFunction(IsDeterministic = true
    , IsPrecise = false, DataAccess = DataAccessKind.None)]
  public static SqlInt32 CRC32(SqlBinary data)
  {
    UInt32 rem = InitialReminder32;

    for (int i = 0; i < data.Length; i++)
    {
      rem = (rem >> 8 ) ^ CRCTable32[(rem & 0xff) ^ data[i]];
    }
    /* Interface back to SQL server */
    unchecked
    {
      return (SqlInt32)(Int32)(rem ^ FinalCRC16_XOR);
    }
  }

  #region constants for CRC16
  const UInt16 FinalCRC16_XOR = 0x0000;
  const UInt16 InitialReminder16 = 0x0000;
  const UInt16 Polynomial16 = 0xA001;
  private static readonly UInt16[] CRCTable16 = {
    	 0x0000,0xc0c1,0xc181,0x0140,0xc301,0x03c0,0x0280,0xc241
        ,0xc601,0x06c0,0x0780,0xc741,0x0500,0xc5c1,0xc481,0x0440
        ,0xcc01,0x0cc0,0x0d80,0xcd41,0x0f00,0xcfc1,0xce81,0x0e40
        ,0x0a00,0xcac1,0xcb81,0x0b40,0xc901,0x09c0,0x0880,0xc841
        ,0xd801,0x18c0,0x1980,0xd941,0x1b00,0xdbc1,0xda81,0x1a40
        ,0x1e00,0xdec1,0xdf81,0x1f40,0xdd01,0x1dc0,0x1c80,0xdc41
        ,0x1400,0xd4c1,0xd581,0x1540,0xd701,0x17c0,0x1680,0xd641
        ,0xd201,0x12c0,0x1380,0xd341,0x1100,0xd1c1,0xd081,0x1040
        ,0xf001,0x30c0,0x3180,0xf141,0x3300,0xf3c1,0xf281,0x3240
        ,0x3600,0xf6c1,0xf781,0x3740,0xf501,0x35c0,0x3480,0xf441
        ,0x3c00,0xfcc1,0xfd81,0x3d40,0xff01,0x3fc0,0x3e80,0xfe41
        ,0xfa01,0x3ac0,0x3b80,0xfb41,0x3900,0xf9c1,0xf881,0x3840
        ,0x2800,0xe8c1,0xe981,0x2940,0xeb01,0x2bc0,0x2a80,0xea41
        ,0xee01,0x2ec0,0x2f80,0xef41,0x2d00,0xedc1,0xec81,0x2c40
        ,0xe401,0x24c0,0x2580,0xe541,0x2700,0xe7c1,0xe681,0x2640
        ,0x2200,0xe2c1,0xe381,0x2340,0xe101,0x21c0,0x2080,0xe041
        ,0xa001,0x60c0,0x6180,0xa141,0x6300,0xa3c1,0xa281,0x6240
        ,0x6600,0xa6c1,0xa781,0x6740,0xa501,0x65c0,0x6480,0xa441
        ,0x6c00,0xacc1,0xad81,0x6d40,0xaf01,0x6fc0,0x6e80,0xae41
        ,0xaa01,0x6ac0,0x6b80,0xab41,0x6900,0xa9c1,0xa881,0x6840
        ,0x7800,0xb8c1,0xb981,0x7940,0xbb01,0x7bc0,0x7a80,0xba41
        ,0xbe01,0x7ec0,0x7f80,0xbf41,0x7d00,0xbdc1,0xbc81,0x7c40
        ,0xb401,0x74c0,0x7580,0xb541,0x7700,0xb7c1,0xb681,0x7640
        ,0x7200,0xb2c1,0xb381,0x7340,0xb101,0x71c0,0x7080,0xb041
        ,0x5000,0x90c1,0x9181,0x5140,0x9301,0x53c0,0x5280,0x9241
        ,0x9601,0x56c0,0x5780,0x9741,0x5500,0x95c1,0x9481,0x5440
        ,0x9c01,0x5cc0,0x5d80,0x9d41,0x5f00,0x9fc1,0x9e81,0x5e40
        ,0x5a00,0x9ac1,0x9b81,0x5b40,0x9901,0x59c0,0x5880,0x9841
        ,0x8801,0x48c0,0x4980,0x8941,0x4b00,0x8bc1,0x8a81,0x4a40
        ,0x4e00,0x8ec1,0x8f81,0x4f40,0x8d01,0x4dc0,0x4c80,0x8c41
        ,0x4400,0x84c1,0x8581,0x4540,0x8701,0x47c0,0x4680,0x8641
        ,0x8201,0x42c0,0x4380,0x8341,0x4100,0x81c1,0x8081,0x4040
    };
  #endregion

  [Microsoft.SqlServer.Server.SqlFunction(IsDeterministic = true
    , IsPrecise = false, DataAccess = DataAccessKind.None)]
  public static SqlInt16 CRC16_Naive(SqlBinary data)
  {
    Int32 length = (Int32)data.Length;
    if (length == 0)
      return 0;

    UInt16 rem = InitialReminder16;
    for (int i = 0; i < length; i++)
    {
      rem = (UInt16)(rem ^ data[i]);
      for (int j = 0; j < 8; j++)
      {
        if ((rem & 0x0001) == 0x0001)
        {   // if rightmost (least significant) bit is set
          rem = (UInt16)((rem >> 1) ^ Polynomial16); /* Polynomial */
        }
        else
        {
          rem = (UInt16)(rem >> 1);
        }
      }
    }
    /* Interface back to SQL server */
    unchecked
    {
      return (SqlInt16)(Int16)(rem ^ FinalCRC16_XOR);
    }
  }

  [Microsoft.SqlServer.Server.SqlFunction(IsDeterministic = true
    , IsPrecise = false, DataAccess = DataAccessKind.None)]
  public static SqlInt16 CRC16(SqlBinary data)
  {
    /* Need ugly 32-bit int here because of silly behavior 
       of shift operator in .NET */
    UInt16 rem = InitialReminder16;
    for (int i = 0; i < data.Length; i++)
    {
      rem = (UInt16)((rem >> 8 ) ^ CRCTable16[(rem & 0xff) ^ data[i]]);
    }
    /* Interface back to SQL server */
    unchecked
    {
      return (SqlInt16)(Int16)(rem ^ FinalCRC16_XOR);
    }
  }
}

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