Disk ARchive 2.4.2
crc.hpp
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00001 /*********************************************************************/
00002 // dar - disk archive - a backup/restoration program
00003 // Copyright (C) 2002-2052 Denis Corbin
00004 //
00005 // This program is free software; you can redistribute it and/or
00006 // modify it under the terms of the GNU General Public License
00007 // as published by the Free Software Foundation; either version 2
00008 // of the License, or (at your option) any later version.
00009 //
00010 // This program is distributed in the hope that it will be useful,
00011 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00012 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00013 // GNU General Public License for more details.
00014 //
00015 // You should have received a copy of the GNU General Public License
00016 // along with this program; if not, write to the Free Software
00017 // Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
00018 //
00019 // to contact the author : http://dar.linux.free.fr/email.html
00020 /*********************************************************************/
00021 // $Id: crc.hpp,v 1.8 2011/02/11 20:23:42 edrusb Rel $
00022 //
00023 /*********************************************************************/
00024 
00028 
00029 #ifndef CRC_HPP
00030 #define CRC_HPP
00031 
00032 #include "../my_config.h"
00033 
00034 #include <string>
00035 #include <list>
00036 
00037 #include "integers.hpp"
00038 #include "storage.hpp"
00039 #include "infinint.hpp"
00040 
00041 namespace libdar
00042 {
00043 
00046 
00047     class crc
00048     {
00049     public:
00050         static const U_I OLD_CRC_SIZE = 2;
00051 
00052         crc(U_I width = 1);
00053         crc(const infinint & width);
00054         crc(const crc & ref) : i_cyclic(1) { copy_from(ref); };
00055         const crc & operator = (const crc & ref) { destroy(); copy_from(ref); return *this; };
00056         ~crc() { destroy(); };
00057 
00058         bool operator == (const crc & ref) const;
00059         bool operator != (const crc & ref) const { return ! (*this == ref); };
00060 
00061         void compute(const infinint & offset, const char *buffer, U_I length);
00062         void compute(const char *buffer, U_I length); // for sequential read only
00063         void clear();
00064         void dump(generic_file & f) const;
00065         void read(generic_file & f);
00066         void old_read(generic_file & f);
00067         std::string crc2str() const;
00068         void resize(const infinint & width);
00069         void resize(U_I width) { resize_non_infinint(width); };
00070         void resize_based_on(const crc & ref) { resize(ref.get_size()); };
00071         infinint get_size() const { return infinint_mode ? i_size : n_size; };
00072 
00073         static void set_crc_pointer(crc * & dst, const crc *src);
00074 
00075     private:
00076 
00077         bool infinint_mode;                           //< true for infinint mode
00078                                                       // ---
00079         infinint i_size;                              //< size of the checksum (infinint mode)
00080         storage::iterator i_pointer;                  //< points to the next byte to modify (infinint mode)
00081         storage i_cyclic;                             //< the checksum storage (infinint mode)
00082                                                       // ---
00083         U_I n_size;                                   //< size of checksum (non infinint mode)
00084         unsigned char *n_pointer;                     //< points to the next byte to modify (non infinint mode)
00085         unsigned char *n_cyclic;                      //< the checksum storage (non infinint mode)
00086 
00087         void copy_from(const crc & ref);
00088         void destroy();
00089         void resize_infinint(const infinint & width);
00090         void resize_non_infinint(U_I width);
00091     };
00092 
00093 
00095 
00096 } // end of namespace
00097 
00098 
00099 #endif
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