1#ifndef CRYPTOPP_CRC32_H
2#define CRYPTOPP_CRC32_H
3
4#include "cryptlib.h"
5
6NAMESPACE_BEGIN(CryptoPP)
7
8const word32 CRC32_NEGL = 0xffffffffL;
9
10#ifdef IS_LITTLE_ENDIAN
11#define CRC32_INDEX(c) (c & 0xff)
12#define CRC32_SHIFTED(c) (c >> 8)
13#else
14#define CRC32_INDEX(c) (c >> 24)
15#define CRC32_SHIFTED(c) (c << 8)
16#endif
17
18//! CRC Checksum Calculation
19class CRC32 : public HashTransformation
20{
21public:
22	CRYPTOPP_CONSTANT(DIGESTSIZE = 4)
23	CRC32();
24	void Update(const byte *input, size_t length);
25	void TruncatedFinal(byte *hash, size_t size);
26	unsigned int DigestSize() const {return DIGESTSIZE;}
27    static const char * StaticAlgorithmName() {return "CRC32";}
28    std::string AlgorithmName() const {return StaticAlgorithmName();}
29
30	void UpdateByte(byte b) {m_crc = m_tab[CRC32_INDEX(m_crc) ^ b] ^ CRC32_SHIFTED(m_crc);}
31	byte GetCrcByte(size_t i) const {return ((byte *)&(m_crc))[i];}
32
33private:
34	void Reset() {m_crc = CRC32_NEGL;}
35
36	static const word32 m_tab[256];
37	word32 m_crc;
38};
39
40NAMESPACE_END
41
42#endif
43