/*
 * Compilation Copyright (c) 1995-2019 by Wei Dai.  All rights reserved.
 *	This copyright applies only to this software distribution package
 *	as a compilation, and does not imply a copyright on any particular
 *	file in the package.
 * 
 *	Boost Software License - Version 1.0 - August 17th, 2003
 *
 *	Permission is hereby granted, free of charge, to any person or organization
 *	obtaining a copy of the software and accompanying documentation covered by
 *	this license (the "Software") to use, reproduce, display, distribute,
 *	execute, and transmit the Software, and to prepare derivative works of the
 *	Software, and to permit third-parties to whom the Software is furnished to
 *	do so, all subject to the following:
 * 
 *	The copyright notices in the Software and this entire statement, including
 *	the above license grant, this restriction and the following disclaimer,
 *	must be included in all copies of the Software, in whole or in part, and
 *	all derivative works of the Software, unless such copies or derivative
 *	works are solely in the form of machine-executable object code generated by
 *	a source language processor.
 *
 *	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *	FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
 *	SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
 *	FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
 *	ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 *	DEALINGS IN THE SOFTWARE.
 */

// crc.h - originally written and placed in the public domain by Wei Dai

/// \file crc.h
/// \brief Classes for CRC-32 and CRC-32C checksum algorithm

#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

/// \brief CRC-32 Checksum Calculation
/// \details Uses CRC polynomial 0xEDB88320
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;
};

/// \brief CRC-32C Checksum Calculation
/// \details Uses CRC polynomial 0x82F63B78
/// \since Crypto++ 5.6.4
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
