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 // Common/CRC.h

 #ifndef __COMMON_CRC_H

 #define __COMMON_CRC_H

 #include <stddef.h>

 #include "Types.h"

 class CCRC

 {

   UInt32 _value;

 public:

 	static UInt32 Table[256];

 	static void InitTable();

   CCRC():  _value(0xFFFFFFFF){};

   void Init() { _value = 0xFFFFFFFF; }

   void UpdateByte(Byte v);

   void UpdateUInt16(UInt16 v);

   void UpdateUInt32(UInt32 v);

   void UpdateUInt64(UInt64 v);

   void Update(const void *data, size_t size);

   UInt32 GetDigest() const { return _value ^ 0xFFFFFFFF; } 

   static UInt32 CalculateDigest(const void *data, size_t size)

   {

     CCRC crc;

     crc.Update(data, size);

     return crc.GetDigest();

   }

   static bool VerifyDigest(UInt32 digest, const void *data, size_t size)

   {

     return (CalculateDigest(data, size) == digest);

   }

 };

 #endif