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      1 /*
      2  * File:	crc.h
      3  *
      4  * Copyright (c) Freescale Semiconductor, Inc. All rights reserved.
      5  * See included license file for license details.
      6  */
      7 #if !defined(_crc_h_)
      8 #define CRYPTOPP_CRC32_H
      9 
     10 #include "stdafx.h"
     11 
     12 const uint32_t CRC32_NEGL = 0xffffffffL;
     13 
     14 #ifdef __LITTLE_ENDIAN__
     15 	#define CRC32_INDEX(c) (c & 0xff)
     16 	#define CRC32_SHIFTED(c) (c >> 8)
     17 #else
     18 	#define CRC32_INDEX(c) (c >> 24)
     19 	#define CRC32_SHIFTED(c) (c << 8)
     20 #endif
     21 
     22 //! CRC Checksum Calculation
     23 class CRC32
     24 {
     25 public:
     26 	enum
     27 	{
     28 		DIGESTSIZE = 4
     29 	};
     30 
     31 	CRC32();
     32 
     33 	void update(const uint8_t * input, unsigned length);
     34 
     35 	void truncatedFinal(uint8_t * hash, unsigned size);
     36 
     37 	void updateByte(uint8_t b) { m_crc = m_tab[CRC32_INDEX(m_crc) ^ b] ^ CRC32_SHIFTED(m_crc); }
     38 	uint8_t getCrcByte(unsigned i) const { return ((uint8_t *)&(m_crc))[i]; }
     39 
     40 private:
     41 	void reset() { m_crc = CRC32_NEGL; m_count = 0; }
     42 
     43 	static const uint32_t m_tab[256];
     44 	uint32_t m_crc;
     45     unsigned m_count;
     46 };
     47 
     48 #endif // _crc_h_
     49