crc.h

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// crc.h - originally written and placed in the public domain by Wei Dai
 
 
#ifndef CRYPTOPP_CRC32_H
#define CRYPTOPP_CRC32_H
 
#include "cryptlib.h"
 
NAMESPACE_BEGIN(CryptoPP)
 
const word32 CRC32_NEGL = 0xffffffffL;
 
#if (CRYPTOPP_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
 
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;}
        CRYPTOPP_STATIC_CONSTEXPR 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 reinterpret_cast<const byte *>(&m_crc)[i];}
 
        std::string AlgorithmProvider() const;
 
protected:
        void Reset() {m_crc = CRC32_NEGL;}
 
private:
        static const word32 m_tab[256];
        word32 m_crc;
};
 
class CRC32C : public HashTransformation
{
public:
        CRYPTOPP_CONSTANT(DIGESTSIZE = 4);
        CRC32C();
        void Update(const byte *input, size_t length);
        void TruncatedFinal(byte *hash, size_t size);
        unsigned int DigestSize() const {return DIGESTSIZE;}
        CRYPTOPP_STATIC_CONSTEXPR const char* StaticAlgorithmName() {return "CRC32C";}
        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 reinterpret_cast<const byte *>(&m_crc)[i];}
 
        std::string AlgorithmProvider() const;
 
protected:
        void Reset() {m_crc = CRC32_NEGL;}
 
private:
        static const word32 m_tab[256];
        word32 m_crc;
};
 
NAMESPACE_END
 
#endif