crc.hpp

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/*********************************************************************/
// dar - disk archive - a backup/restoration program
// Copyright (C) 2002-2026 Denis Corbin
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//
// to contact the author, see the AUTHOR file
/*********************************************************************/

 
#ifndef CRC_HPP
#define CRC_HPP
 
#include "../my_config.h"
 
#include <string>
#include <list>
#include "integers.hpp"
#include "storage.hpp"
#include "infinint.hpp"
#include "proto_generic_file.hpp"
 
namespace libdar
{


 
    class crc
    {
    public:
    static constexpr U_I OLD_CRC_SIZE = 2;
 
    crc() {};
    crc(const crc & ref) = default;
    crc(crc && ref) noexcept = default;
    crc & operator = (const crc & ref) = default;
    crc & operator = (crc && ref) noexcept = default;
    virtual ~crc() = default;
 
    virtual bool operator == (const crc & ref) const = 0;
    bool operator != (const crc & ref) const { return ! (*this == ref); };
 
    virtual void compute(const infinint & offset, const char *buffer, U_I length) = 0;
    virtual void compute(const char *buffer, U_I length) = 0; // for sequential read only
    virtual void clear() = 0;
    virtual void dump(proto_generic_file & f) const = 0;
    virtual std::string crc2str() const = 0;
    virtual infinint get_size() const = 0;
    virtual crc *clone() const = 0;
    };

    extern crc *create_crc_from_file(proto_generic_file & f, bool old = false);

    extern crc *create_crc_from_size(infinint width);

 
    class crc_i : public crc
    {
    public:
    crc_i(const infinint & width);
    crc_i(const infinint & width, proto_generic_file & f);
    crc_i(const crc_i & ref) : size(ref.size), cyclic(ref.size) { copy_data_from(ref); pointer = cyclic.begin(); };
    crc_i(crc_i && ref) noexcept = default;
    crc_i & operator = (const crc_i & ref) { copy_from(ref); return *this; };
    crc_i & operator = (crc_i && ref) noexcept = default;
    ~crc_i() = default;
 
    bool operator == (const crc & ref) const override;
 
    virtual void compute(const infinint & offset, const char *buffer, U_I length) override;
    virtual void compute(const char *buffer, U_I length) override; // for sequential read only
    virtual void clear() override;
    virtual void dump(proto_generic_file & f) const override;
    virtual std::string crc2str() const override;
    virtual infinint get_size() const override { return size; };
 
    protected:
    virtual crc *clone() const override { crc *tmp = new (std::nothrow) crc_i(*this); if(tmp == nullptr) throw Ememory("crc"); return tmp; };
 
    private:
 
    infinint size;                              
    storage::iterator pointer;                  
    storage cyclic;                             
 
    void copy_from(const crc_i & ref);
    void copy_data_from(const crc_i & ref);
    };
 

 
    class crc_n : public crc
    {
    public:
 
    crc_n(U_I width);
    crc_n(U_I width, proto_generic_file & f);
    crc_n(const crc_n & ref) { copy_from(ref); };
    crc_n(crc_n && ref) noexcept = default;
    crc_n & operator = (const crc_n & ref);
    crc_n & operator = (crc_n && ref) noexcept = default;
    ~crc_n() { destroy(); };
 
    bool operator == (const crc & ref) const override;
 
    virtual void compute(const infinint & offset, const char *buffer, U_I length) override;
    virtual void compute(const char *buffer, U_I length) override; // for sequential read only
    virtual void clear() override;
    virtual void dump(proto_generic_file & f) const override;
    virtual std::string crc2str() const override;
    virtual infinint get_size() const override { return size; };
 
    protected:
    virtual crc *clone() const override { crc *tmp = new (std::nothrow) crc_n(*this); if(tmp == nullptr) throw Ememory("crc"); return tmp; };
 
    private:
 
    U_I size;                                   
    unsigned char *pointer;                     
    unsigned char *cyclic;                      
 
    void alloc(U_I width);
    void copy_from(const crc_n & ref);
    void copy_data_from(const crc_n & ref);
    void destroy();
    };
 

 
} // end of namespace
 
 
#endif