/****************************************************************************

** libebml : parse EBML files, see http://embl.sourceforge.net/

**

** <file/class description>

**

** Copyright (C) 2002-2010 Steve Lhomme.  All rights reserved.

**

** This file is part of libebml.

**

** This library 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 2.1 of the License, or (at your option) any later version.

**

** This library 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 this library; if not, write to the Free Software

** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

**

** See http://www.gnu.org/licenses/lgpl-2.1.html for LGPL licensing information.

**

** Contact license@matroska.org if any conditions of this licensing are

** not clear to you.

**

**********************************************************************/

/*!

  \file

  \version \$Id$

  \author Steve Lhomme     <robux4 @ users.sf.net>

  \author Jory Stone       <jcsston @ toughguy.net>

*/

#ifndef LIBEBML_CRC32_H

#define LIBEBML_CRC32_H

#include <cassert>

#include "EbmlTypes.h"

#include "EbmlBinary.h"

namespace libebml {

DECLARE_EBML_BINARY(EbmlCrc32)

  public:

    EbmlCrc32(const EbmlCrc32 & ElementToClone);

    EbmlCrc32 &operator =(const EbmlCrc32 &) = default;

    bool ValidateSize() const override {return IsFiniteSize() && (GetSize() == 4);}

    filepos_t RenderData(IOCallback & output, bool bForceRender, bool bWithDefault = false) override;

    filepos_t ReadData(IOCallback & input, ScopeMode ReadFully = SCOPE_ALL_DATA) override;

//    filepos_t UpdateSize(bool bWithDefault = false);

    bool IsDefaultValue() const override {

      return false;

    }

    void AddElementCRC32(EbmlElement &ElementToCRC);

    bool CheckElementCRC32(EbmlElement &ElementToCRC);

    /*!

      Use this to quickly check a CRC32 with some data

      \return True if inputCRC matches CRC32 generated from input data

    */

    static bool CheckCRC(uint32 inputCRC, const binary *input, uint32 length);

    /*!

      Calls Update() and Finalize(), use to create a CRC32 in one go

    */

    void FillCRC32(const binary *input, uint32 length);

    /*!

      Add data to the CRC table, in other words process some data bit by bit

    */

    void Update(const binary *input, uint32 length);

    /*!

      Use this with Update() to Finalize() or Complete the CRC32

    */

    void Finalize();

    /*!

      Returns a uint32 that has the value of the CRC32

    */

    uint32 GetCrc32() const {

      return m_crc_final;

    }

    void ForceCrc32(uint32 NewValue) { m_crc_final = NewValue; SetValueIsSet();}

#if defined(EBML_STRICT_API)

    private:

#else

    protected:

#endif

    void ResetCRC();

    void UpdateByte(binary b);

    static const uint32 m_tab[256];

    uint32 m_crc;

    uint32 m_crc_final;

        EBML_CONCRETE_CLASS(EbmlCrc32)

};

template <class T>

inline unsigned int GetAlignment(T * /* dummy */=nullptr) // VC60 workaround

{

#if defined(_MSC_VER) && (_MSC_VER >= 1300)

  return __alignof(T);

#elif defined(__GNUC__)

  return __alignof__(T);

#else

  return sizeof(T);

#endif

}

template <class T>

inline bool IsPowerOf2(T n)

{

  return n > 0 && (n & (n-1)) == 0;

}

template <class T1, class T2>

inline T2 ModPowerOf2(T1 a, T2 b)

{

  assert(IsPowerOf2(b));

  return static_cast<T2>(a) & (b-1);

}

inline bool IsAlignedOn(const void *p, unsigned int alignment)

{

  return IsPowerOf2(alignment) ? ModPowerOf2(reinterpret_cast<uintptr_t>(p), alignment) == 0 : reinterpret_cast<uintptr_t>(p) % alignment == 0;

}

template <class T>

inline bool IsAligned(const void *p, T * /* dummy */=nullptr)  // VC60 workaround

{

  return IsAlignedOn(p, GetAlignment<T>());

}

} // namespace libebml

#endif // LIBEBML_CRC32_H