summaryrefslogtreecommitdiffstats
path: root/CryptoPP/crc.h
blob: f75ea384c2b775a252340167013b286125a9cfb7 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
#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