CRC32算法

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Text;
 4 using System.IO;
 5 
 6 namespace GetCRC32
 7 {
 8     class CRC32Cls
 9     {
10         protected ulong[] Crc32Table;
11         //生成CRC32码表
12         public void GetCRC32Table() 
13         {
14             ulong Crc;
15             Crc32Table = new ulong[256];
16             int i,j;
17             for(i = 0;i < 256; i++) 
18             {
19                 Crc = (ulong)i;
20                 for (j = 8; j > 0; j--)
21                 {
22                     if ((Crc & 1) == 1)
23                         Crc = (Crc >> 1) ^ 0xEDB88320;
24                     else
25                         Crc >>= 1;
26                 }
27                 Crc32Table[i] = Crc;
28             }
29         }
30 
31         //获取字符串的CRC32校验值
32         public ulong GetCRC32Str(string sInputString)
33         {
34             //生成码表
35             GetCRC32Table();
36             byte[] buffer = System.Text.ASCIIEncoding.ASCII.GetBytes(sInputString);
37             ulong value = 0xffffffff;
38             int len = buffer.Length;
39             for (int i = 0; i < len; i++)
40             {
41                 value = (value >> 8) ^ Crc32Table[(value & 0xFF)^ buffer[i]];
42             }
43             return value ^ 0xffffffff; 
44         }
45     }
46 }

CRC16算法

 1          public static byte[] CRC16(string sInputString)
 2          {
 3              byte[] data = System.Text.ASCIIEncoding.ASCII.GetBytes(sInputString);
 4              int len = data.Length;
 5              if (len > 0)
 6              {
 7                  ushort crc = 0xFFFF;
 8 
 9                  for (int i = 0; i < len; i++)
10                  {
11                      crc = (ushort)(crc ^ (data[i]));
12                      for (int j = 0; j < 8; j++)
13                      {
14                          crc = (crc & 1) != 0 ? (ushort)((crc >> 1) ^ 0xA001) : (ushort)(crc >> 1);
15                      }
16                  }
17                  byte hi = (byte)((crc & 0xFF00) >> 8);  //高位置
18                  byte lo = (byte)(crc & 0x00FF);         //低位置
19 
20                  return new byte[] { hi, lo };
21              }
22              return new byte[] { 0, 0 };
23          }
24 
25 // ASCII码转为字符串
26          public static string ByteToString(byte[] arr, bool isReverse)
27          {
28              try
29              {
30                  byte hi = arr[0], lo = arr[1];
31                  return Convert.ToString(isReverse ? hi + lo * 0x100 : hi * 0x100 + lo, 16).ToUpper().PadLeft(4, '0');
32              }
33              catch (Exception ex) { throw (ex); }
34          }

CRC32/CRC16算法C#中的实现

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