C#文件CRC计算

public sealed class CRC 
 
 
 

   { 
 
 
 

       private static ushort[] CRC16Table = null; 
 
 
 

       private static uint[] CRC32Table = null; 
 
 
 

       private static void MakeCRC16Table() 
 
 
 

       { 
 
 
 

           if (CRC16Table != null) return; 
 
 
 

           CRC16Table = new ushort[256]; 
 
 
 

           for (ushort i = 0; i < 256; i++) 
 
 
 

           { 
 
 
 

               ushort vCRC = i; 
 
 
 

               for (int j = 0; j < 8; j++) 
 
 
 

                   if (vCRC % 2 == 0) 
 
 
 

                       vCRC = (ushort)(vCRC >> 1); 
 
 
 

                   else vCRC = (ushort)((vCRC >> 1) ^ 0x8408); 
 
 
 

               CRC16Table[i] = vCRC; 
 
 
 

           } 
 
 
 

       } 
 
 
 

       private static void MakeCRC32Table() 
 
 
 

       { 
 
 
 

           if (CRC32Table != null) return; 
 
 
 

           CRC32Table = new uint[256]; 
 
 
 

           for (uint i = 0; i < 256; i++) 
 
 
 

           { 
 
 
 

               uint vCRC = i; 
 
 
 

               for (int j = 0; j < 8; j++) 
 
 
 

                   if (vCRC % 2 == 0) 
 
 
 

                       vCRC = (uint)(vCRC >> 1); 
 
 
 

                   else vCRC = (uint)((vCRC >> 1) ^ 0xEDB88320); 
 
 
 

               CRC32Table[i] = vCRC; 
 
 
 

           } 
 
 
 

       } 
 
 
 

       public static ushort UpdateCRC16(byte AByte, ushort ASeed) 
 
 
 

       { 
 
 
 

           return (ushort)(CRC16Table[(ASeed & 0x000000FF) ^ AByte] ^ (ASeed >> 8)); 
 
 
 

       } 
 
 
 

       public static uint UpdateCRC32(byte AByte, uint ASeed) 
 
 
 

       { 
 
 
 

           return (uint)(CRC32Table[(ASeed & 0x000000FF) ^ AByte] ^ (ASeed >> 8)); 
 
 
 

       } 
 
 
 

       public static ushort CRC16(byte[] ABytes) 
 
 
 

       { 
 
 
 

           MakeCRC16Table(); 
 
 
 

           ushort Result = 0xFFFF; 
 
 
 

           foreach (byte vByte in ABytes) 
 
 
 

               Result = UpdateCRC16(vByte, Result); 
 
 
 

           return (ushort)(~Result); 
 
 
 

       } 
 
 
 

       public static ushort CRC16(string AString, Encoding AEncoding) 
 
 
 

       { 
 
 
 

           return CRC16(AEncoding.GetBytes(AString)); 
 
 
 

       } 
 
 
 

       public static ushort CRC16(string AString) 
 
 
 

       { 
 
 
 

           return CRC16(AString, Encoding.UTF8); 
 
 
 

       } 
 
 
 

       public static uint CRC32(byte[] ABytes) 
 
 
 

       { 
 
 
 

           MakeCRC32Table(); 
 
 
 

           uint Result = 0xFFFFFFFF; 
 
 
 

           foreach (byte vByte in ABytes) 
 
 
 

               Result = UpdateCRC32(vByte, Result); 
 
 
 

           return (uint)(~Result); 
 
 
 

       } 
 
 
 

       public static uint CRC32(string AString, Encoding AEncoding) 
 
 
 

       { 
 
 
 

           return CRC32(AEncoding.GetBytes(AString)); 
 
 
 

       } 
 
 
 

       public static uint CRC32(string AString) 
 
 
 

       { 
 
 
 

           return CRC32(AString, Encoding.UTF8); 
 
 
 

       } 
 
 
 

   }