src/add-ons/media/plugins/matroska/libebml/ebml/EbmlCrc32.h

   1 /****************************************************************************
   2 ** libebml : parse EBML files, see http://embl.sourceforge.net/
   3 **
   4 ** <file/class description>
   5 **
   6 ** Copyright (C) 2002-2005 Steve Lhomme.  All rights reserved.
   7 **
   8 ** This file is part of libebml.
   9 **
  10 ** This library is free software; you can redistribute it and/or
  11 ** modify it under the terms of the GNU Lesser General Public
  12 ** License as published by the Free Software Foundation; either
  13 ** version 2.1 of the License, or (at your option) any later version.
  14 **
  15 ** This library is distributed in the hope that it will be useful,
  16 ** but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18 ** Lesser General Public License for more details.
  19 **
  20 ** You should have received a copy of the GNU Lesser General Public
  21 ** License along with this library; if not, write to the Free Software
  22 ** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  23 **
  24 ** See http://www.matroska.org/license/lgpl/ for LGPL licensing information.
  25 **
  26 ** Contact license@matroska.org if any conditions of this licensing are
  27 ** not clear to you.
  28 **
  29 **********************************************************************/
  30
  31 /*!
  32         \file
  33         \version \$Id: EbmlCrc32.h 1155 2005-05-06 11:43:38Z robux4 $
  34         \author Steve Lhomme     <robux4 @ users.sf.net>
  35         \author Jory Stone       <jcsston @ toughguy.net>
  36 */
  37 #ifndef LIBEBML_CRC32_H
  38 #define LIBEBML_CRC32_H
  39
  40 #include "EbmlTypes.h"
  41 #include "EbmlBinary.h"
  42
  43 START_LIBEBML_NAMESPACE
  44
  45 const uint32 CRC32_NEGL = 0xffffffffL;
  46
  47 #ifdef WORDS_BIGENDIAN
  48 # define CRC32_INDEX(c) (c >> 24)
  49 # define CRC32_SHIFTED(c) (c << 8)
  50 #else
  51 # define CRC32_INDEX(c) (c & 0xff)
  52 # define CRC32_SHIFTED(c) (c >> 8)
  53 #endif
  54
  55 class EBML_DLL_API EbmlCrc32 : public EbmlBinary {
  56         public:
  57                 EbmlCrc32();
  58                 EbmlCrc32(const EbmlCrc32 & ElementToClone);
  59                 static EbmlElement & Create() {return *(new EbmlCrc32);}
  60                 const EbmlCallbacks & Generic() const {return ClassInfos;}
  61                 bool ValidateSize() const {return (Size == 4);}
  62                 uint32 RenderData(IOCallback & output, bool bForceRender, bool bKeepIntact = false);
  63                 uint64 ReadData(IOCallback & input, ScopeMode ReadFully = SCOPE_ALL_DATA);
  64 //              uint64 UpdateSize(bool bKeepIntact = false);
  65
  66                 static const EbmlCallbacks ClassInfos;
  67                 bool IsDefaultValue() const {
  68                         return false;
  69                 }
  70
  71                 operator const EbmlId &() const {return ClassInfos.GlobalId;}
  72                 bool IsYourId(const EbmlId & TestId) const;
  73
  74                 void AddElementCRC32(EbmlElement &ElementToCRC);
  75                 bool CheckElementCRC32(EbmlElement &ElementToCRC);
  76
  77                 /*!
  78                         CRC Checksum Calculation
  79                 */
  80                 enum {DIGESTSIZE = 4};
  81
  82                 /*!
  83                         Use this to quickly check a CRC32 with some data
  84                         \return True if inputCRC matches CRC32 generated from input data
  85                 */
  86                 static bool CheckCRC(uint32 inputCRC, const binary *input, uint32 length);
  87                 /*!
  88                         Calls Update() and Finalize(), use to create a CRC32 in one go
  89                 */
  90                 void FillCRC32(const binary *input, uint32 length);
  91                 /*!
  92                         Add data to the CRC table, in other words process some data bit by bit
  93                 */
  94                 void Update(const binary *input, uint32 length);
  95                 /*!
  96                         Use this with Update() to Finalize() or Complete the CRC32
  97                 */
  98                 void Finalize();
  99                 /*!
 100                         Returns a uint32 that has the value of the CRC32
 101                 */
 102                 uint32 GetCrc32() const {
 103                         return m_crc_final;
 104                 };
 105
 106                 void ForceCrc32(uint32 NewValue) { m_crc_final = NewValue; bValueIsSet = true;}
 107
 108                 EbmlElement * Clone() const;
 109
 110         protected:
 111                 void ResetCRC() {m_crc = CRC32_NEGL;}
 112                 void UpdateByte(binary b) {m_crc = m_tab[CRC32_INDEX(m_crc) ^ b] ^ CRC32_SHIFTED(m_crc);}
 113
 114                 static const uint32 m_tab[256];
 115                 uint32 m_crc;
 116                 uint32 m_crc_final;
 117 };
 118
 119 template <class T>
 120 inline unsigned int GetAlignment(T *dummy=NULL) // VC60 workaround
 121 {
 122 #if (_MSC_VER >= 1300)
 123         return __alignof(T);
 124 #elif defined(__GNUC__)
 125         return __alignof__(T);
 126 #else
 127         return sizeof(T);
 128 #endif
 129 }
 130
 131 template <class T>
 132 inline bool IsPowerOf2(T n)
 133 {
 134         return n > 0 && (n & (n-1)) == 0;
 135 }
 136
 137 template <class T1, class T2>
 138 inline T2 ModPowerOf2(T1 a, T2 b)
 139 {
 140         assert(IsPowerOf2(b));
 141         return T2(a) & (b-1);
 142 }
 143
 144 inline bool IsAlignedOn(const void *p, unsigned int alignment)
 145 {
 146         return IsPowerOf2(alignment) ? ModPowerOf2((unsigned long)p, alignment) == 0 : (unsigned long)p % alignment == 0;
 147 }
 148
 149 template <class T>
 150 inline bool IsAligned(const void *p, T *dummy=NULL)     // VC60 workaround
 151 {
 152         return IsAlignedOn(p, GetAlignment<T>());
 153 }
 154
 155 END_LIBEBML_NAMESPACE
 156
 157 #endif // LIBEBML_CRC32_H