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###############################################################################
# core math lib for BigInt, representing big numbers by the GMP library
package Math::BigInt::GMP;
use strict;
use 5.006002;
# use warnings; # dont use warnings for older Perls
use vars qw/$VERSION/;
$VERSION = '1.24';
use XSLoader;
XSLoader::load "Math::BigInt::GMP", $VERSION;
sub import { } # catch and throw away
sub api_version() { 2; } # we are compatible with MBI v1.83 and up
BEGIN
{
# both _num and _str just return a string
*_str = \&_num;
}
##############################################################################
# Routines not present here are in GMP.xs
sub _digit
{
# return the nth digit, negative values count backward; this is costly!
my ($c,$x,$n) = @_;
$n++; substr( Math::BigInt::GMP::_num($c,$x), -$n, 1 );
}
###############################################################################
# routine to test internal state for corruptions
sub _check
{
# no checks yet, pull it out from the test suite
my ($x) = $_[1];
return "$x is not a reference to Math::BigInt::GMP"
if ref($x) ne 'Math::BigInt::GMP';
0;
}
sub _log_int
{
my ($c,$x,$base) = @_;
# X == 0 => NaN
return if _is_zero($c,$x);
$base = _new($c,2) unless defined $base;
$base = _new($c,$base) unless ref $base;
# BASE 0 or 1 => NaN
return if _is_zero($c,$base) || _is_one($c,$base);
my $cmp = _acmp($c,$x,$base); # X == BASE => 1
if ($cmp == 0)
{
# return one
return (_one($c), 1);
}
# X < BASE
if ($cmp < 0)
{
return (_zero($c),undef);
}
# Compute a guess for the result based on:
# $guess = int ( length_in_base_10(X) / ( log(base) / log(10) ) )
my $len = _alen($c,$x);
my $log = log( _num($c,$base) ) / log(10);
# calculate now a guess based on the values obtained above:
my $x_org = _copy($c,$x);
# keep the reference to $x, modifying it in place
_set($c, $x, int($len / $log) - 1);
my $trial = _pow ($c, _copy($c, $base), $x);
my $a = _acmp($c,$trial,$x_org);
if ($a == 0)
{
return ($x,1);
}
elsif ($a > 0)
{
# too big, shouldn't happen
_div($c,$trial,$base); _dec($c, $x);
}
# find the real result by going forward:
my $base_mul = _mul($c, _copy($c,$base), $base);
my $two = _two($c);
while (($a = _acmp($c, $trial, $x_org)) < 0)
{
_mul($c,$trial,$base_mul); _add($c, $x, $two);
}
my $exact = 1;
if ($a > 0)
{
# overstepped the result
_dec($c, $x);
_div($c,$trial,$base);
$a = _acmp($c,$trial,$x_org);
if ($a > 0)
{
_dec($c, $x);
}
$exact = 0 if $a != 0;
}
($x,$exact);
}
1;
__END__
=pod
=head1 NAME
Math::BigInt::GMP - Use the GMP library for Math::BigInt routines
=head1 SYNOPSIS
Provides support for big integer calculations via means of the GMP c-library.
Math::BigInt::GMP now no longer uses Math::GMP, but provides it's own XS layer
to access the GMP c-library. This cut's out another (perl sub routine) layer
and also reduces the memory footprint by not loading Math::GMP and Carp at
all.
=head1 LICENSE
This program is free software; you may redistribute it and/or modify it under
the same terms as Perl itself.
=head1 AUTHOR
Tels <http://bloodgate.com/> in 2001-2007.
Thanx to Chip Turner for providing Math::GMP, which was inspiring my work.
=head1 SEE ALSO
L<Math::BigInt>, L<Math::BigInt::Calc>.
=cut
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