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 1.14.2.2 2007/07/22 16:35:00 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 &= (const infinint & ref);
00100         infinint & operator |= (const infinint & ref);
00101         infinint & operator ^= (const infinint & ref);
00102         infinint & operator >>= (U_32 bit);
00103         infinint & operator >>= (infinint bit);
00104         infinint & operator <<= (U_32 bit);
00105         infinint & operator <<= (infinint bit);
00106         infinint operator ++(int a)
00107             { E_BEGIN infinint ret = *this; ++(*this); return ret; E_END("infinint::operator ++", "int") };
00108         infinint operator --(int a)
00109             { E_BEGIN infinint ret = *this; --(*this); return ret; E_END("infinint::operator --", "int") };
00110         infinint & operator ++()
00111             { E_BEGIN return *this += 1; E_END("infinint::operator ++", "()") };
00112         infinint & operator --()
00113             { E_BEGIN return *this -= 1; E_END("infinint::operator --", "()") };
00114 
00115         U_32 operator % (U_32 arg) const
00116             { E_BEGIN return modulo(arg); E_END("infinint::operator %","") };
00117 
00118             // increment the argument up to a legal value for its storage type and decrement the object in consequence
00119             // note that the initial value of the argument is not ignored !
00120             // when the object is null the value of the argument stays the same as before
00121         template <class T>void unstack(T &v)
00122             { E_BEGIN infinint_unstack_to(v); E_END("infinint::unstack", typeid(v).name()) }
00123 
00124         infinint get_storage_size() const { return field->size(); };
00125             // it returns number of byte of information necessary to store the integer
00126 
00127         unsigned char operator [] (const infinint & position) const;
00128             // return in big endian order the information byte storing the integer
00129 
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 bool operator <= (const infinint &, const infinint &);
00134         friend bool operator != (const infinint &, const infinint &);
00135         friend bool operator >= (const infinint &, const infinint &);
00136         friend void euclide(infinint a, const infinint &b, infinint &q, infinint &r);
00137 
00138     private :
00139         static const int TG = 4;
00140 
00141         enum endian { big_endian, little_endian, not_initialized };
00142         typedef unsigned char group[TG];
00143 
00144         storage *field;
00145 
00146         bool is_valid() const;
00147         void build_from_file(generic_file & x);
00148         void reduce(); // put the object in canonical form : no leading byte equal to zero
00149         void copy_from(const infinint & ref);
00150         void detruit();
00151         void make_at_least_as_wider_as(const infinint & ref);
00152         template <class T> void infinint_from(T a);
00153         template <class T> void infinint_unstack_to(T &a);
00154         template <class T> T modulo(T arg) const;
00155         signed int difference(const infinint & b) const; // gives the sign of (*this - arg) but only the sign !
00156 
00158             // static statments
00159             //
00160         static endian used_endian;
00161         static void setup_endian();
00162     };
00163 
00164 
00165 #define OPERATOR(OP) inline bool operator OP (const infinint &a, const infinint &b) \
00166 { \
00167     E_BEGIN \
00168     return a.difference(b) OP 0; \
00169     E_END("operator OP", "infinint, infinint") \
00170 }
00171 
00172     OPERATOR(<)
00173     OPERATOR(>)
00174     OPERATOR(<=)
00175     OPERATOR(>=)
00176     OPERATOR(==)
00177     OPERATOR(!=)
00178 
00179     infinint operator + (const infinint &, const infinint &);
00180     infinint operator - (const infinint &, const infinint &);
00181     infinint operator * (const infinint &, const infinint &);
00182     infinint operator * (const infinint &, const unsigned char);
00183     infinint operator * (const unsigned char, const infinint &);
00184     infinint operator / (const infinint &, const infinint &);
00185     infinint operator % (const infinint &, const infinint &);
00186     infinint operator & (const infinint & a, const infinint & bit);
00187     infinint operator | (const infinint & a, const infinint & bit);
00188     infinint operator ^ (const infinint & a, const infinint & bit);
00189     infinint operator >> (const infinint & a, U_32 bit);
00190     infinint operator >> (const infinint & a, const infinint & bit);
00191     infinint operator << (const infinint & a, U_32 bit);
00192     infinint operator << (const infinint & a, const infinint & bit);
00193     void euclide(infinint a, const infinint &b, infinint &q, infinint &r);
00194     template <class T> inline void euclide(T a, T b, T & q, T &r)
00195     {
00196         E_BEGIN
00197         q = a/b; r = a%b;
00198         E_END("euclide", "")
00199     }
00200 
00201     inline infinint & infinint::operator /= (const infinint & ref)
00202     {
00203         E_BEGIN
00204         *this = *this / ref;
00205         return *this;
00206         E_END("infinint::operator /=", "")
00207     }
00208 
00209     inline infinint & infinint::operator %= (const infinint & ref)
00210     {
00211         E_BEGIN
00212         *this = *this % ref;
00213         return *this;
00214         E_END("infinint::operator %=", "")
00215     }
00216 
00217 
00221 
00222     template <class T> infinint infinint::power(const T & exponent) const
00223     {
00224         infinint ret = 1;
00225         for(T count = 0; count < exponent; ++count)
00226             ret *= *this;
00227 
00228         return ret;
00229     }
00230 
00231     template <class T> T infinint::modulo(T arg) const
00232     {
00233         E_BEGIN
00234         infinint tmp = *this % infinint(arg);
00235         T ret = 0;
00236         unsigned char *debut = (unsigned char *)(&ret);
00237         unsigned char *ptr = debut + sizeof(T) - 1;
00238         storage::iterator it = tmp.field->rbegin();
00239 
00240         while(it != tmp.field->rend() && ptr >= debut)
00241         {
00242             *ptr = *it;
00243             --ptr;
00244             --it;
00245         }
00246 
00247         if(it != tmp.field->rend())
00248             throw SRC_BUG; // could not put all the data in the returned value !
00249 
00250         if(used_endian == big_endian)
00251             int_tools_swap_bytes(debut, sizeof(T));
00252 
00253         return ret;
00254         E_END("infinint::modulo", "")
00255     }
00256 
00257 
00258     template <class T> void infinint::infinint_from(T a)
00259     {
00260         E_BEGIN
00261         U_I size = sizeof(a);
00262         S_I direction = +1;
00263         unsigned char *ptr, *fin;
00264 
00265         if(used_endian == not_initialized)
00266             setup_endian();
00267 
00268         if(used_endian == big_endian)
00269         {
00270             direction = -1;
00271             ptr = (unsigned char *)(&a) + (size - 1);
00272             fin = (unsigned char *)(&a) - 1;
00273         }
00274         else
00275         {
00276             direction = +1;
00277             ptr = (unsigned char *)(&a);
00278             fin = (unsigned char *)(&a) + size;
00279         }
00280 
00281         while(ptr != fin && *ptr == 0)
00282         {
00283             ptr += direction;
00284             --size;
00285         }
00286 
00287         if(size == 0)
00288         {
00289             size = 1;
00290             ptr -= direction;
00291         }
00292 
00293         field = new storage(size);
00294         if(field != NULL)
00295         {
00296             storage::iterator it = field->begin();
00297 
00298             while(ptr != fin)
00299             {
00300                 *it = *ptr;
00301                 ++it;
00302                 ptr += direction;
00303             }
00304             if(it != field->end())
00305                 throw SRC_BUG; // size mismatch in this algorithm
00306         }
00307         else
00308             throw Ememory("template infinint::infinint_from");
00309 
00310         E_END("infinint::infinint_from", "")
00311     }
00312 
00313     template <class T> void infinint::infinint_unstack_to(T &a)
00314     {
00315         E_BEGIN
00316             // T is supposed to be an unsigned "integer"
00317             // (ie.: sizeof() returns the width of the storage bit field  and no sign bit is present)
00318             // Note : static here avoids the recalculation of max_T at each call
00319         static const T max_T = int_tools_maxof_agregate(T(0));
00320         infinint step = max_T - a;
00321 
00322         if(*this < step)
00323         {
00324             T transfert = 0;
00325             unsigned char *debut = (unsigned char *)&transfert;
00326             unsigned char *ptr = debut + sizeof(transfert) - 1;
00327             storage::iterator it = field->rbegin();
00328 
00329             while(ptr >= debut && it != field->rend())
00330             {
00331                 *ptr = *it;
00332                 --ptr;
00333                 --it;
00334             }
00335             if(used_endian == big_endian)
00336                 int_tools_swap_bytes(debut, sizeof(transfert));
00337             a += transfert;
00338             *this -= *this;
00339         }
00340         else
00341         {
00342             *this -= step;
00343             a = max_T;
00344         }
00345         E_END("infinint::infinint_unstack_to", "")
00346     }
00347 
00348 } // end of namespace
00349 
00350 #endif

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