crc.h

来自「各种加密算法的集合」· C头文件 代码 · 共 31 行

#ifndef CRYPTOPP_CRC32_H 
#define CRYPTOPP_CRC32_H 
 
#include "cryptlib.h" 
 
NAMESPACE_BEGIN(CryptoPP) 
 
/* Must use this value instead of ~0 due to 64-bit computers */ 
const unsigned long CRC32_NEGL = 0xffffffffL; 
 
class CRC32 : public HashModule 
{ 
public: 
	CRC32(); 
	void Update(const byte *input, unsigned int length); 
	void Final(byte *hash); 
	unsigned int DigestSize() const {return 4;} 
 
	void Reset() {curr_crc = CRC32_NEGL;} 
	void UpdateByte(byte b) {curr_crc = crc_32_tab[byte(curr_crc ^ b)] ^ (curr_crc >> 8);} 
	word32 GetCrc() const {return curr_crc ^ CRC32_NEGL;} 
 
private: 
	static const unsigned long crc_32_tab[256]; 
	unsigned long curr_crc; 
}; 
 
NAMESPACE_END 
 
#endif