Checksum.h

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/*********************************************************\
 *  File: Checksum.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_CHECKSUM_H__
#define __PLCORE_CHECKSUM_H__
#pragma once


//[-------------------------------------------------------]
//[ Includes                                              ]
//[-------------------------------------------------------]
#include "PLCore/String/String.h"


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


//[-------------------------------------------------------]
//[ Forward declarations                                  ]
//[-------------------------------------------------------]
class File;


//[-------------------------------------------------------]
//[ Classes                                               ]
//[-------------------------------------------------------]
/**
*  @brief
*    Abstract checksum ("digital fingerprint") base class
*
*  @remarks
*    Normally a checksum is used to detect errors after transmission or storage. Before transmission
*    or storage of data, a checksum of the data is calculated and send/saved. Afterwards the received
*    data is verified by using the checksum to confirm that no changes occurred on transit.
*
*  @note
*    - Each time a checksum is calculated, an instance of the class is created and destroyed at the end
*/
class Checksum {


    //[-------------------------------------------------------]
    //[ Public functions                                      ]
    //[-------------------------------------------------------]
    public:
        /**
        *  @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, empty on error (maybe empty buffer?)
        */
        PLCORE_API String Get(const uint8 *pnBuffer, uint32 nNumOfBytes);

        /**
        *  @brief
        *    Returns the checksum of a given string
        *
        *  @param[in] sString
        *    String to create the checksum from, the original internal format is used -
        *    if it's a Unicode string, Unicode will be used to get the checksum
        *
        *  @return
        *    The checksum of the given string, empty on error (maybe unknown class?)
        *
        *  @note
        *     - sString: "My text" != L"My text" (ASCII != Unicode even if the text itself is the same!)
        */
        PLCORE_API String Get(const String &sString);

        /**
        *  @brief
        *    Returns the checksum of a given file
        *
        *  @param[in] cFile
        *    File to create the checksum from (MUST be opened and readable!)
        *
        *  @return
        *    The checksum of the given file, empty string on error
        *    (maybe unknown class or the given file is invalid?)
        *
        *  @note
        *    - The current file offset is not changed
        */
        PLCORE_API String Get(File &cFile);

        /**
        *  @brief
        *    Returns the checksum of a given file
        *
        *  @param[in] sFilename
        *    Name of the file to create the checksum from
        *
        *  @return
        *    The checksum of the given file, empty on error (maybe unknown class or invalid file?)
        */
        PLCORE_API String GetFile(const String &sFilename);


    //[-------------------------------------------------------]
    //[ Protected functions                                   ]
    //[-------------------------------------------------------]
    protected:
        /**
        *  @brief
        *    Default constructor
        */
        PLCORE_API Checksum();

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


    //[-------------------------------------------------------]
    //[ Protected virtual Checksum functions                  ]
    //[-------------------------------------------------------]
    protected:
        /**
        *  @brief
        *    Implementation of main checksum algorithm
        *
        *  @param[in] nInput
        *    Input block
        *  @param[in] nInputLen
        *    Length of input block in bytes
        *
        *  @remarks
        *    Computes the partial checksum for 'nInputLen' bytes of data in 'Input'.
        */
        virtual void Update(const uint8 nInput[], uint32 nInputLen) = 0;

        /**
        *  @brief
        *    Implementation of main checksum algorithm; ends the checksum calculation.
        *
        *  @return
        *    The final hexadecimal checksum result
        *    (without the 0x prefix and with lower case hex characters)
        *
        *  @remarks
        *    Performs the final checksum calculation. 'Update' does most of the work,
        *    this function just finishes the calculation.
        */
        virtual String Final() = 0;


    //[-------------------------------------------------------]
    //[ Private functions                                     ]
    //[-------------------------------------------------------]
    private:
        /**
        *  @brief
        *    Copy constructor
        *
        *  @param[in] cSource
        *    Source to copy from
        */
        Checksum(const Checksum &cSource);

        /**
        *  @brief
        *    Copy operator
        *
        *  @param[in] cSource
        *    Source to copy from
        *
        *  @return
        *    Reference to this instance
        */
        Checksum &operator =(const Checksum &cSource);


};


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


#endif // __PLCORE_CHECKSUM_H__