ChecksumCRC32.h

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/*********************************************************\
 *  File: ChecksumCRC32.h                                *
 *
 *  Copyright (C) 2002-2012 The PixelLight Team (http://www.pixellight.org/)
 *
 *  This file is part of PixelLight.
 *
 *  PixelLight is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  PixelLight is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 *  GNU Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with PixelLight. If not, see <http://www.gnu.org/licenses/>.
\*********************************************************/


#ifndef __PLCORE_CHECKSUMCRC32_H__
#define __PLCORE_CHECKSUMCRC32_H__
#pragma once


//[-------------------------------------------------------]
//[ Includes                                              ]
//[-------------------------------------------------------]
#include "PLCore/Container/Array.h"
#include "PLCore/Tools/Checksum.h"


//[-------------------------------------------------------]
//[ Namespace                                             ]
//[-------------------------------------------------------]
namespace PLCore {


//[-------------------------------------------------------]
//[ Classes                                               ]
//[-------------------------------------------------------]
/**
*  @brief
*    CRC32 (cyclic redundancy check) checksum
*
*  @remarks
*    This implementation is using the official polynomial (0x04C11DB7) used by CRC32 in
*    PKZip, WinZip and Ethernet. Often times the polynomial shown reversed as 0xEDB88320.
*
*  @note
*    - CRC32 produces a 32-bit/4-byte hash
*/
class ChecksumCRC32 : public Checksum {


    //[-------------------------------------------------------]
    //[ Public functions                                      ]
    //[-------------------------------------------------------]
    public:
        /**
        *  @brief
        *    Constructor
        */
        PLCORE_API ChecksumCRC32();

        /**
        *  @brief
        *    Destructor
        */
        PLCORE_API virtual ~ChecksumCRC32();

        /**
        *  @brief
        *    Returns the current CRC32 checksum
        *
        *  @return
        *    Current CRC32 checksum
        */
        PLCORE_API uint32 GetChecksum() const;

        /**
        *  @brief
        *    Returns the checksum of a given buffer
        *
        *  @param[in] pnBuffer
        *    Buffer to create the checksum from (MUST be valid!)
        *  @param[in] nNumOfBytes
        *    Number of bytes of the given buffer (MUST be valid!)
        *
        *  @return
        *    The checksum of the given buffer
        */
        PLCORE_API uint32 GetChecksum(const uint8 *pnBuffer, uint32 nNumOfBytes);


    //[-------------------------------------------------------]
    //[ Private functions                                     ]
    //[-------------------------------------------------------]
    private:
        /**
        *  @brief
        *    Initializes the CRC32 table
        */
        void Init();

        /**
        *  @brief
        *    Reflection part of the the CRC32 table initialization
        *
        *  @param[in] nReflection
        *    Reflection value
        *  @param[in] nCharacter
        *    Character to reflect
        *
        *  @return
        *    The reflected character
        *
        *  @remarks
        *    Reflection is a requirement for the official CRC-32 standard.
        */
        uint32 Reflect(uint32 nReflection, char nCharacter) const;


    //[-------------------------------------------------------]
    //[ Private data                                          ]
    //[-------------------------------------------------------]
    private:
        static Array<uint32> m_lstCRC32Table;   /**< Static CRC32 table */
        uint32               m_nCRC32;          /**< Current CRC32 checksum */


    //[-------------------------------------------------------]
    //[ Private virtual Checksum functions                    ]
    //[-------------------------------------------------------]
    private:
        virtual void Update(const uint8 nInput[], uint32 nInputLen) override;
        virtual String Final() override;


};


//[-------------------------------------------------------]
//[ Namespace                                             ]
//[-------------------------------------------------------]
} // PLCore


#endif // __PLCORE_CHECKSUMCRC32_H__