real_infinint.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 : dar.linux@free.fr
00020 /*********************************************************************/
00021 // $Id: real_infinint.hpp,v 1.14 2005/09/25 19:05:42 edrusb Rel $
00022 //
00023 /*********************************************************************/
00024 
00030 
00031 #ifndef REAL_INFININT_HPP
00032 #define REAL_INFININT_HPP
00033 
00034 #include "../my_config.h"
00035 
00036 extern "C"
00037 {
00038 #if HAVE_SYS_TYPES_H
00039 #include <sys/types.h>
00040 #endif
00041 } // end extern "C"
00042 
00043 #include <typeinfo>
00044 #include "storage.hpp"
00045 #include "integers.hpp"
00046 #include "int_tools.hpp"
00047 
00048 namespace libdar
00049 {
00050     class generic_file;
00051     class user_interaction;
00052 
00054 
00057     class infinint
00058     {
00059     public :
00060 
00061 #if SIZEOF_OFF_T > SIZEOF_TIME_T
00062 #if SIZEOF_OFF_T > SIZEOF_SIZE_T
00063         infinint(off_t a = 0)
00064             { E_BEGIN infinint_from(a); E_END("infinint::infinint", "off_t") };
00065 #else
00066         infinint(size_t a = 0)
00067             { E_BEGIN infinint_from(a); E_END("infinint::infinint", "size_t") };
00068 #endif
00069 #else
00070 #if SIZEOF_TIME_T > SIZEOF_SIZE_T
00071         infinint(time_t a = 0)
00072             { E_BEGIN infinint_from(a); E_END("infinint::infinint", "time_t") };
00073 #else
00074         infinint(size_t a = 0)
00075             { E_BEGIN infinint_from(a); E_END("infinint::infinint", "size_t") };
00076 #endif
00077 #endif
00078 
00079         infinint(const infinint & ref)
00080             { E_BEGIN; copy_from(ref); E_END("infinint::infinint", "const infinint &"); }
00081         infinint(user_interaction & dialog, S_I *fd, generic_file *x); // read an infinint from a file
00082         ~infinint()
00083             { E_BEGIN detruit(); E_END("infinint::~infinint","") };
00084 
00085         infinint & operator = (const infinint & ref)
00086             { E_BEGIN detruit(); copy_from(ref); return *this; E_END("infinint::operator =","") };
00087 
00088         void dump(user_interaction & dialog, int fd) const; // write byte sequence to file
00089         void dump(generic_file &x) const; // write byte sequence to file
00090         void read(generic_file &f) { detruit(); build_from_file(f); };
00091 
00092         infinint & operator += (const infinint & ref);
00093         infinint & operator -= (const infinint & ref);
00094         infinint & operator *= (unsigned char arg);
00095         infinint & operator *= (const infinint & ref);
00096         template <class T> infinint power(const T & exponent) const;
00097         inline infinint & operator /= (const infinint & ref);
00098         inline infinint & operator %= (const infinint & ref);
00099         infinint & operator >>= (U_32 bit);
00100         infinint & operator >>= (infinint bit);
00101         infinint & operator <<= (U_32 bit);
00102         infinint & operator <<= (infinint bit);
00103         infinint operator ++(int a)
00104             { E_BEGIN infinint ret = *this; ++(*this); return ret; E_END("infinint::operator ++", "int") };
00105         infinint operator --(int a)
00106             { E_BEGIN infinint ret = *this; --(*this); return ret; E_END("infinint::operator --", "int") };
00107         infinint & operator ++()
00108             { E_BEGIN return *this += 1; E_END("infinint::operator ++", "()") };
00109         infinint & operator --()
00110             { E_BEGIN return *this -= 1; E_END("infinint::operator --", "()") };
00111 
00112         U_32 operator % (U_32 arg) const
00113             { E_BEGIN return modulo(arg); E_END("infinint::operator %","") };
00114 
00115             // increment the argument up to a legal value for its storage type and decrement the object in consequence
00116             // note that the initial value of the argument is not ignored !
00117             // when the object is null the value of the argument stays the same as before
00118         template <class T>void unstack(T &v)
00119             { E_BEGIN infinint_unstack_to(v); E_END("infinint::unstack", typeid(v).name()) }
00120 
00121         infinint get_storage_size() const { return field->size(); };
00122             // it returns number of byte of information necessary to store the integer
00123 
00124         unsigned char operator [] (const infinint & position) const;
00125             // return in big endian order the information byte storing the integer
00126 
00127         friend bool operator < (const infinint &, const infinint &);
00128         friend bool operator == (const infinint &, const infinint &);
00129         friend bool operator > (const infinint &, const infinint &);
00130         friend bool operator <= (const infinint &, const infinint &);
00131         friend bool operator != (const infinint &, const infinint &);
00132         friend bool operator >= (const infinint &, const infinint &);
00133         friend void euclide(infinint a, const infinint &b, infinint &q, infinint &r);
00134 
00135     private :
00136         static const int TG = 4;
00137 
00138         enum endian { big_endian, little_endian, not_initialized };
00139         typedef unsigned char group[TG];
00140 
00141         storage *field;
00142 
00143         bool is_valid() const;
00144         void build_from_file(generic_file & x);
00145         void reduce(); // put the object in canonical form : no leading byte equal to zero
00146         void copy_from(const infinint & ref);
00147         void detruit();
00148         void make_at_least_as_wider_as(const infinint & ref);
00149         template <class T> void infinint_from(T a);
00150         template <class T> void infinint_unstack_to(T &a);
00151         template <class T> T modulo(T arg) const;
00152         signed int difference(const infinint & b) const; // gives the sign of (*this - arg) but only the sign !
00153 
00155             // static statments
00156             //
00157         static endian used_endian;
00158         static void setup_endian();
00159     };
00160 
00161 
00162 #define OPERATOR(OP) inline bool operator OP (const infinint &a, const infinint &b) \
00163 { \
00164     E_BEGIN \
00165     return a.difference(b) OP 0; \
00166     E_END("operator OP", "infinint, infinint") \
00167 }
00168 
00169     OPERATOR(<)
00170     OPERATOR(>)
00171     OPERATOR(<=)
00172     OPERATOR(>=)
00173     OPERATOR(==)
00174     OPERATOR(!=)
00175 
00176     infinint operator + (const infinint &, const infinint &);
00177     infinint operator - (const infinint &, const infinint &);
00178     infinint operator * (const infinint &, const infinint &);
00179     infinint operator * (const infinint &, const unsigned char);
00180     infinint operator * (const unsigned char, const infinint &);
00181     infinint operator / (const infinint &, const infinint &);
00182     infinint operator % (const infinint &, const infinint &);
00183     infinint operator >> (const infinint & a, U_32 bit);
00184     infinint operator >> (const infinint & a, const infinint & bit);
00185     infinint operator << (const infinint & a, U_32 bit);
00186     infinint operator << (const infinint & a, const infinint & bit);
00187     void euclide(infinint a, const infinint &b, infinint &q, infinint &r);
00188     template <class T> inline void euclide(T a, T b, T & q, T &r)
00189     {
00190         E_BEGIN
00191         q = a/b; r = a%b;
00192         E_END("euclide", "")
00193     }
00194 
00195     inline infinint & infinint::operator /= (const infinint & ref)
00196     {
00197         E_BEGIN
00198         *this = *this / ref;
00199         return *this;
00200         E_END("infinint::operator /=", "")
00201     }
00202 
00203     inline infinint & infinint::operator %= (const infinint & ref)
00204     {
00205         E_BEGIN
00206         *this = *this % ref;
00207         return *this;
00208         E_END("infinint::operator %=", "")
00209     }
00210 
00211 
00215 
00216     template <class T> infinint infinint::power(const T & exponent) const
00217     {
00218         infinint ret = 1;
00219         for(T count = 0; count < exponent; count++)
00220             ret *= *this;
00221 
00222         return ret;
00223     }
00224 
00225     template <class T> T infinint::modulo(T arg) const
00226     {
00227         E_BEGIN
00228         infinint tmp = *this % infinint(arg);
00229         T ret = 0;
00230         unsigned char *debut = (unsigned char *)(&ret);
00231         unsigned char *ptr = debut + sizeof(T) - 1;
00232         storage::iterator it = tmp.field->rbegin();
00233 
00234         while(it != tmp.field->rend() && ptr >= debut)
00235             *(ptr--) = *(it--);
00236 
00237         if(it != tmp.field->rend())
00238             throw SRC_BUG; // could not put all the data in the returned value !
00239 
00240         if(used_endian == big_endian)
00241             int_tools_swap_bytes(debut, sizeof(T));
00242 
00243         return ret;
00244         E_END("infinint::modulo", "")
00245     }
00246 
00247 
00248     template <class T> void infinint::infinint_from(T a)
00249     {
00250         E_BEGIN
00251         U_I size = sizeof(a);
00252         S_I direction = +1;
00253         unsigned char *ptr, *fin;
00254 
00255         if(used_endian == not_initialized)
00256             setup_endian();
00257 
00258         if(used_endian == big_endian)
00259         {
00260             direction = -1;
00261             ptr = (unsigned char *)(&a) + (size - 1);
00262             fin = (unsigned char *)(&a) - 1;
00263         }
00264         else
00265         {
00266             direction = +1;
00267             ptr = (unsigned char *)(&a);
00268             fin = (unsigned char *)(&a) + size;
00269         }
00270 
00271         while(ptr != fin && *ptr == 0)
00272         {
00273             ptr += direction;
00274             size--;
00275         }
00276 
00277         if(size == 0)
00278         {
00279             size = 1;
00280             ptr -= direction;
00281         }
00282 
00283         field = new storage(size);
00284         if(field != NULL)
00285         {
00286             storage::iterator it = field->begin();
00287 
00288             while(ptr != fin)
00289             {
00290                 *(it++) = *ptr;
00291                 ptr += direction;
00292             }
00293             if(it != field->end())
00294                 throw SRC_BUG; // size mismatch in this algorithm
00295         }
00296         else
00297             throw Ememory("template infinint::infinint_from");
00298 
00299         E_END("infinint::infinint_from", "")
00300     }
00301 
00302     template <class T> void infinint::infinint_unstack_to(T &a)
00303     {
00304         E_BEGIN
00305             // T is supposed to be an unsigned "integer"
00306             // (ie.: sizeof() returns the width of the storage bit field  and no sign bit is present)
00307             // Note : static here avoids the recalculation of max_T at each call
00308         static const T max_T = int_tools_maxof_agregate(T(0));
00309         infinint step = max_T - a;
00310 
00311         if(*this < step)
00312         {
00313             T transfert = 0;
00314             unsigned char *debut = (unsigned char *)&transfert;
00315             unsigned char *ptr = debut + sizeof(transfert) - 1;
00316             storage::iterator it = field->rbegin();
00317 
00318             while(ptr >= debut && it != field->rend())
00319                 *(ptr--) = *(it--);
00320 
00321             if(used_endian == big_endian)
00322                 int_tools_swap_bytes(debut, sizeof(transfert));
00323             a += transfert;
00324             *this -= *this;
00325         }
00326         else
00327         {
00328             *this -= step;
00329             a = max_T;
00330         }
00331         E_END("infinint::infinint_unstack_to", "")
00332     }
00333 
00334 } // end of namespace
00335 
00336 #endif

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