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real_infinint.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 REAL_INFININT_HPP
#define REAL_INFININT_HPP
#include "../my_config.h"
extern "C"
{
#if HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
} // end extern "C"
#include <typeinfo>
#include "integers.hpp"
#include "int_tools.hpp"
#include "proto_generic_file.hpp"
#include "storage.hpp"
#define ZEROED_SIZE 50
namespace libdar
{
class infinint
{
public :
#if SIZEOF_OFF_T > SIZEOF_TIME_T
#if SIZEOF_OFF_T > SIZEOF_SIZE_T
infinint(off_t a = 0) { infinint_from(a); };
#else
infinint(size_t a = 0) { infinint_from(a); };
#endif
#else
#if SIZEOF_TIME_T > SIZEOF_SIZE_T
infinint(time_t a = 0) { infinint_from(a); };
#else
infinint(size_t a = 0) { infinint_from(a); };
#endif
#endif
infinint(proto_generic_file & x);
infinint(const infinint & ref) { copy_from(ref); }
infinint(infinint && ref) noexcept { field = nullptr; move_from(std::move(ref)); };
infinint & operator = (const infinint & ref) { detruit(); copy_from(ref); return *this; };
infinint & operator = (infinint && ref) noexcept { move_from(std::move(ref)); return *this; }
~infinint() { detruit(); };
void dump(proto_generic_file &x) const; // write byte sequence to file
void read(proto_generic_file &f) { detruit(); build_from_file(f); };
infinint & operator += (const infinint & ref);
infinint & operator -= (const infinint & ref);
infinint & operator *= (unsigned char arg);
infinint & operator *= (const infinint & ref);
template <class T> infinint power(const T & exponent) const;
inline infinint & operator /= (const infinint & ref);
inline infinint & operator %= (const infinint & ref);
infinint & operator &= (const infinint & ref);
infinint & operator |= (const infinint & ref);
infinint & operator ^= (const infinint & ref);
infinint & operator >>= (U_32 bit);
infinint & operator >>= (infinint bit);
infinint & operator <<= (U_32 bit);
infinint & operator <<= (infinint bit);
infinint operator ++(int a)
{ infinint ret = *this; ++(*this); return ret; };
infinint operator --(int a)
{ infinint ret = *this; --(*this); return ret; };
infinint & operator ++()
{ return *this += 1; };
infinint & operator --()
{ return *this -= 1; };
U_32 operator % (U_32 arg) const
{ return modulo(arg); };
template <class T>void unstack(T &v)
{ infinint_unstack_to(v); }
infinint get_storage_size() const noexcept { return field->size(); };
unsigned char operator [] (const infinint & position) const;
bool is_zero() const;
friend bool operator < (const infinint &, const infinint &);
friend bool operator == (const infinint &, const infinint &);
friend bool operator > (const infinint &, const infinint &);
friend bool operator <= (const infinint &, const infinint &);
friend bool operator != (const infinint &, const infinint &);
friend bool operator >= (const infinint &, const infinint &);
friend void euclide(infinint a, const infinint &b, infinint &q, infinint &r);
static bool is_system_big_endian();
private :
static constexpr int TG = 4;
enum endian { big_endian, little_endian, not_initialized };
using group = unsigned char[TG];
storage *field;
bool is_valid() const noexcept;
void build_from_file(proto_generic_file & x);
void reduce(); // put the object in canonical form : no leading byte equal to zero
void copy_from(const infinint & ref);
void move_from(infinint && ref) noexcept { std::swap(field, ref.field); };
void detruit();
void make_at_least_as_wider_as(const infinint & ref);
template <class T> void infinint_from(T a);
template <class T> T max_val_of(T x);
template <class T> void infinint_unstack_to(T &a);
template <class T> T modulo(T arg) const;
signed int difference(const infinint & b) const; // gives the sign of (*this - arg) but only the sign !
// static statments
//
static endian used_endian;
static U_8 zeroed_field[ZEROED_SIZE];
static void setup_endian();
};
#define OPERATOR(OP) inline bool operator OP (const infinint &a, const infinint &b) \
{ \
return a.difference(b) OP 0; \
}
OPERATOR(<)
OPERATOR(>)
OPERATOR(<=)
OPERATOR(>=)
OPERATOR(==)
OPERATOR(!=)
infinint operator + (const infinint &, const infinint &);
infinint operator - (const infinint &, const infinint &);
infinint operator * (const infinint &, const infinint &);
infinint operator * (const infinint &, const unsigned char);
infinint operator * (const unsigned char, const infinint &);
infinint operator / (const infinint &, const infinint &);
infinint operator % (const infinint &, const infinint &);
infinint operator & (const infinint & a, const infinint & bit);
infinint operator | (const infinint & a, const infinint & bit);
infinint operator ^ (const infinint & a, const infinint & bit);
infinint operator >> (const infinint & a, U_32 bit);
infinint operator >> (const infinint & a, const infinint & bit);
infinint operator << (const infinint & a, U_32 bit);
infinint operator << (const infinint & a, const infinint & bit);
void euclide(infinint a, const infinint &b, infinint &q, infinint &r);
template <class T> inline void euclide(T a, T b, T & q, T &r)
{
q = a/b; r = a%b;
}
inline infinint & infinint::operator /= (const infinint & ref)
{
*this = *this / ref;
return *this;
}
inline infinint & infinint::operator %= (const infinint & ref)
{
*this = *this % ref;
return *this;
}
template <class T> infinint infinint::power(const T & exponent) const
{
infinint ret = 1;
for(T count = 0; count < exponent; ++count)
ret *= *this;
return ret;
}
template <class T> T infinint::modulo(T arg) const
{
infinint tmp = *this % infinint(arg);
T ret = 0;
unsigned char *debut = (unsigned char *)(&ret);
unsigned char *ptr = debut + sizeof(T) - 1;
storage::iterator it = tmp.field->rbegin();
while(it != tmp.field->rend() && ptr >= debut)
{
*ptr = *it;
--ptr;
--it;
}
// checking for overflow (should never occur, but for sanity, we check it anyway)
while(it != tmp.field->rend()) // field may not be reduced (some zeros are leading)
{
if(*it != 0)
throw SRC_BUG; // could not put all the data in the returned value !
--it;
}
if(used_endian == little_endian)
int_tools_swap_bytes(debut, sizeof(T));
return ret;
}
template <class T> void infinint::infinint_from(T a)
{
U_I size = sizeof(a);
S_I direction = +1;
unsigned char *ptr, *fin;
if(used_endian == not_initialized)
setup_endian();
if(used_endian == little_endian)
{
direction = -1;
ptr = (unsigned char *)(&a) + (size - 1);
fin = (unsigned char *)(&a) - 1;
}
else
{
direction = +1;
ptr = (unsigned char *)(&a);
fin = (unsigned char *)(&a) + size;
}
while(ptr != fin && *ptr == 0)
{
ptr += direction;
--size;
}
if(size == 0)
{
size = 1;
ptr -= direction;
}
field = new (std::nothrow) storage(size);
if(field != nullptr)
{
storage::iterator it = field->begin();
while(ptr != fin)
{
*it = *ptr;
++it;
ptr += direction;
}
if(it != field->end())
throw SRC_BUG; // size mismatch in this algorithm
}
else
throw Ememory("template infinint::infinint_from");
}
template <class T> T infinint::max_val_of(T x)
{
x = 0;
x = ~x;
if(x <= 0) // T is a signed integer type. Note that it should be "x < 0" but to avoid compiler warning when T is unsigned it does not hurt having "x <= 0" here
{
x = 1;
x = int_tools_rotate_right_one_bit(x);
x = ~x;
}
return x;
}
template <class T> void infinint::infinint_unstack_to(T & a)
{
// T is supposed to be an unsigned "integer"
// (ie.: sizeof() returns the width of the storage bit field and no sign bit is present)
// Note : static here avoids the recalculation of max_T at each call
static const T max_T = max_val_of(a);
infinint step = max_T - a;
if(*this < step)
{
T transfert = 0;
unsigned char *debut = (unsigned char *)&transfert;
unsigned char *ptr = debut + sizeof(transfert) - 1;
storage::iterator it = field->rbegin();
while(ptr >= debut && it != field->rend())
{
*ptr = *it;
--ptr;
--it;
}
if(used_endian == little_endian)
int_tools_swap_bytes(debut, sizeof(transfert));
a += transfert;
*this -= *this;
}
else
{
*this -= step;
a = max_T;
}
}
} // end of namespace
#endif
libdar::infinint
the arbitrary large positive integer class
Definition real_infinint.hpp:62
libdar::proto_generic_file
ancestor class of generic_file
Definition proto_generic_file.hpp:55
libdar::storage
arbitrary large storage structure
Definition storage.hpp:53
libdar::infinint::operator[]
unsigned char operator[](const infinint &position) const
return in little endian order the information byte storing the integer
libdar::infinint::unstack
void unstack(T &v)
convert infinint to standard interger types
Definition real_infinint.hpp:124
libdar::infinint::get_storage_size
infinint get_storage_size() const noexcept
it returns number of byte of information necessary to store the integer
Definition real_infinint.hpp:128
libdar::infinint::infinint
infinint(proto_generic_file &x)
read an infinint from a file
libdar::infinint::is_zero
bool is_zero() const
int_tools.hpp
elementary operation for infinint integers
integers.hpp
are defined here basic integer types that tend to be portable
my_config.h
include macro defined by the configure script and some specific additional ones
libdar
libdar namespace encapsulate all libdar symbols
Definition archive.hpp:47
proto_generic_file.hpp
precursor class of generic_file used to avoid cyclic dependencies with storage and infinint
storage.hpp
contains a class that permits arbitrary large data storage