crc.h
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#ifndef CRYPTOPP_CRC32_H
#define CRYPTOPP_CRC32_H
#include "cryptlib.h"
NAMESPACE_BEGIN(CryptoPP)
const word32 CRC32_NEGL = 0xffffffffL;
#ifdef IS_LITTLE_ENDIAN
#define CRC32_INDEX(c) (c & 0xff)
#define CRC32_SHIFTED(c) (c >> 8)
#else
#define CRC32_INDEX(c) (c >> 24)
#define CRC32_SHIFTED(c) (c << 8)
#endif
//! CRC Checksum Calculation
class CRC32 : public HashTransformation
{
public:
CRYPTOPP_CONSTANT(DIGESTSIZE = 4)
CRC32();
void Update(const byte *input, size_t length);
void TruncatedFinal(byte *hash, size_t size);
unsigned int DigestSize() const {return DIGESTSIZE;}
static const char * StaticAlgorithmName() {return "CRC32";}
std::string AlgorithmName() const {return StaticAlgorithmName();}
void UpdateByte(byte b) {m_crc = m_tab[CRC32_INDEX(m_crc) ^ b] ^ CRC32_SHIFTED(m_crc);}
byte GetCrcByte(size_t i) const {return ((byte *)&(m_crc))[i];}
private:
void Reset() {m_crc = CRC32_NEGL;}
static const word32 m_tab[256];
word32 m_crc;
};
NAMESPACE_END
#endif