package Math::BigInt::CalcEmu;

use 5.006002;
use strict;
# use warnings; # dont use warnings for older Perls
use vars qw/$VERSION/;

$VERSION = '1.998';

package Math::BigInt;

# See SYNOPSIS below.

my $CALC_EMU;

BEGIN
{
$CALC_EMU = Math::BigInt->config()->{'lib'};
# register us with MBI to get notified of future lib changes
Math::BigInt::_register_callback( __PACKAGE__, sub { $CALC_EMU = $_[0]; } );
}

sub __emu_band
{
my ($self,$x,$y,$sx,$sy,@r) = @_;

return $x->bzero(@r) if $y->is_zero() || $x->is_zero();

my $sign = 0; # sign of result
$sign = 1 if $sx == -1 && $sy == -1;

my ($bx,$by);

if ($sx == -1) # if x is negative
{
# two's complement: inc and flip all "bits" in $bx
$bx = $x->binc()->as_hex(); # -1 => 0, -2 => 1, -3 => 2 etc
$bx =~ s/-?0x//;
$bx =~ tr/0123456789abcdef/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
}
else
{
$bx = $x->as_hex(); # get binary representation
$bx =~ s/-?0x//;
$bx =~ tr/fedcba9876543210/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
}
if ($sy == -1) # if y is negative
{
# two's complement: inc and flip all "bits" in $by
$by = $y->copy()->binc()->as_hex(); # -1 => 0, -2 => 1, -3 => 2 etc
$by =~ s/-?0x//;
$by =~ tr/0123456789abcdef/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
}
else
{
$by = $y->as_hex(); # get binary representation
$by =~ s/-?0x//;
$by =~ tr/fedcba9876543210/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
}
# now we have bit-strings from X and Y, reverse them for padding
$bx = reverse $bx;
$by = reverse $by;

# padd the shorter string
my $xx = "\x00"; $xx = "\x0f" if $sx == -1;
my $yy = "\x00"; $yy = "\x0f" if $sy == -1;
my $diff = CORE::length($bx) - CORE::length($by);
if ($diff > 0)
{
# if $yy eq "\x00", we can cut $bx, otherwise we need to padd $by
$by .= $yy x $diff;
}
elsif ($diff < 0)
{
# if $xx eq "\x00", we can cut $by, otherwise we need to padd $bx
$bx .= $xx x abs($diff);
}

# and the strings together
my $r = $bx & $by;

# and reverse the result again
$bx = reverse $r;

# One of $x or $y was negative, so need to flip bits in the result.
# In both cases (one or two of them negative, or both positive) we need
# to get the characters back.
if ($sign == 1)
{
$bx =~ tr/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/0123456789abcdef/;
}
else
{
$bx =~ tr/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/fedcba9876543210/;
}

# leading zeros will be stripped by _from_hex()
$bx = '0x' . $bx;
$x->{value} = $CALC_EMU->_from_hex( $bx );

# calculate sign of result
$x->{sign} = '+';
$x->{sign} = '-' if $sign == 1 && !$x->is_zero();

$x->bdec() if $sign == 1;

$x->round(@r);
}

sub __emu_bior
{
my ($self,$x,$y,$sx,$sy,@r) = @_;

return $x->round(@r) if $y->is_zero();

my $sign = 0; # sign of result
$sign = 1 if ($sx == -1) || ($sy == -1);

my ($bx,$by);

if ($sx == -1) # if x is negative
{
# two's complement: inc and flip all "bits" in $bx
$bx = $x->binc()->as_hex(); # -1 => 0, -2 => 1, -3 => 2 etc
$bx =~ s/-?0x//;
$bx =~ tr/0123456789abcdef/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
}
else
{
$bx = $x->as_hex(); # get binary representation
$bx =~ s/-?0x//;
$bx =~ tr/fedcba9876543210/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
}
if ($sy == -1) # if y is negative
{
# two's complement: inc and flip all "bits" in $by
$by = $y->copy()->binc()->as_hex(); # -1 => 0, -2 => 1, -3 => 2 etc
$by =~ s/-?0x//;
$by =~ tr/0123456789abcdef/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
}
else
{
$by = $y->as_hex(); # get binary representation
$by =~ s/-?0x//;
$by =~ tr/fedcba9876543210/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
}
# now we have bit-strings from X and Y, reverse them for padding
$bx = reverse $bx;
$by = reverse $by;

# padd the shorter string
my $xx = "\x00"; $xx = "\x0f" if $sx == -1;
my $yy = "\x00"; $yy = "\x0f" if $sy == -1;
my $diff = CORE::length($bx) - CORE::length($by);
if ($diff > 0)
{
$by .= $yy x $diff;
}
elsif ($diff < 0)
{
$bx .= $xx x abs($diff);
}

# or the strings together
my $r = $bx | $by;

# and reverse the result again
$bx = reverse $r;

# one of $x or $y was negative, so need to flip bits in the result
# in both cases (one or two of them negative, or both positive) we need
# to get the characters back.
if ($sign == 1)
{
$bx =~ tr/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/0123456789abcdef/;
}
else
{
$bx =~ tr/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/fedcba9876543210/;
}

# leading zeros will be stripped by _from_hex()
$bx = '0x' . $bx;
$x->{value} = $CALC_EMU->_from_hex( $bx );

# calculate sign of result
$x->{sign} = '+';
$x->{sign} = '-' if $sign == 1 && !$x->is_zero();

# if one of X or Y was negative, we need to decrement result
$x->bdec() if $sign == 1;

$x->round(@r);
}

sub __emu_bxor
{
my ($self,$x,$y,$sx,$sy,@r) = @_;

return $x->round(@r) if $y->is_zero();

my $sign = 0; # sign of result
$sign = 1 if $x->{sign} ne $y->{sign};

my ($bx,$by);

if ($sx == -1) # if x is negative
{
# two's complement: inc and flip all "bits" in $bx
$bx = $x->binc()->as_hex(); # -1 => 0, -2 => 1, -3 => 2 etc
$bx =~ s/-?0x//;
$bx =~ tr/0123456789abcdef/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
}
else
{
$bx = $x->as_hex(); # get binary representation
$bx =~ s/-?0x//;
$bx =~ tr/fedcba9876543210/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
}
if ($sy == -1) # if y is negative
{
# two's complement: inc and flip all "bits" in $by
$by = $y->copy()->binc()->as_hex(); # -1 => 0, -2 => 1, -3 => 2 etc
$by =~ s/-?0x//;
$by =~ tr/0123456789abcdef/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
}
else
{
$by = $y->as_hex(); # get binary representation
$by =~ s/-?0x//;
$by =~ tr/fedcba9876543210/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/;
}
# now we have bit-strings from X and Y, reverse them for padding
$bx = reverse $bx;
$by = reverse $by;

# padd the shorter string
my $xx = "\x00"; $xx = "\x0f" if $sx == -1;
my $yy = "\x00"; $yy = "\x0f" if $sy == -1;
my $diff = CORE::length($bx) - CORE::length($by);
if ($diff > 0)
{
$by .= $yy x $diff;
}
elsif ($diff < 0)
{
$bx .= $xx x abs($diff);
}

# xor the strings together
my $r = $bx ^ $by;

# and reverse the result again
$bx = reverse $r;

# one of $x or $y was negative, so need to flip bits in the result
# in both cases (one or two of them negative, or both positive) we need
# to get the characters back.
if ($sign == 1)
{
$bx =~ tr/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/0123456789abcdef/;
}
else
{
$bx =~ tr/\x0f\x0e\x0d\x0c\x0b\x0a\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00/fedcba9876543210/;
}

# leading zeros will be stripped by _from_hex()
$bx = '0x' . $bx;
$x->{value} = $CALC_EMU->_from_hex( $bx );

# calculate sign of result
$x->{sign} = '+';
$x->{sign} = '-' if $sx != $sy && !$x->is_zero();

$x->bdec() if $sign == 1;

$x->round(@r);
}

##############################################################################
##############################################################################

1;
__END__

=head1 NAME

Math::BigInt::CalcEmu - Emulate low-level math with BigInt code

=head1 SYNOPSIS

use Math::BigInt::CalcEmu;

=head1 DESCRIPTION

Contains routines that emulate low-level math functions in BigInt, e.g.
optional routines the low-level math package does not provide on its own.

Will be loaded on demand and called automatically by BigInt.

Stuff here is really low-priority to optimize, since it is far better to
implement the operation in the low-level math library directly, possible even
using a call to the native lib.

=head1 METHODS

=head2 __emu_bxor

=head2 __emu_band

=head2 __emu_bior

=head1 LICENSE

This program is free software; you may redistribute it and/or modify it under
the same terms as Perl itself.

=head1 AUTHORS

(c) Tels http://bloodgate.com 2003, 2004 - based on BigInt code by
Tels from 2001-2003.

=head1 SEE ALSO

L<Math::BigInt>, L<Math::BigFloat>,
L<Math::BigInt::GMP> and L<Math::BigInt::Pari>.

=cut