File Coverage

blib/lib/Math/ModInt/BigInt.pm

Criterion	Covered	Total	%
statement	78	78	100.0
branch	20	20	100.0
condition	6	6	100.0
subroutine	21	21	100.0
pod	2	2	100.0
total	127	127	100.0

package Math::ModInt::BigInt;

use 5.006;
use strict;
use warnings;
use Carp qw(croak);
use Math::BigInt;
use constant _ISSUE_CPAN_RT79060 => -1 != Math::BigInt->new(-2) / 3;

# ----- object definition -----

# Math::ModInt::BigInt=ARRAY(...)

# .......... index ..........   # .......... value ..........
use constant F_RESIDUE => 0;    # residue r, 0 <= r < m
use constant F_MODULUS => 1;    # modulus m
use constant NFIELDS   => 2;

# ----- class data -----

BEGIN {
    require Math::ModInt;
    our @ISA     = 'Math::ModInt';
    our $VERSION = '0.013';
}

# ----- overridden methods -----

sub _NEG {
    my ($this) = @_;
    return $this->_NEW(-$this->residue);
}

sub _ADD {
    my ($this, $that) = @_;
    return $this->_NEW($this->residue + $that->residue);
}

sub _SUB {
    my ($this, $that) = @_;
    return $this->_NEW($this->residue - $that->residue);
}

sub _MUL {
    my ($this, $that) = @_;
    return $this->_NEW($this->residue * $that->residue);
}

sub _DIV {
    my ($this, $that) = @_;
    my $i = $that->residue->copy->bmodinv($that->modulus);
    return $this->undefined if $i->is_nan;
    return $this->_NEW($this->residue * $i);
}

sub _POW {
    my ($this, $exp) = @_;
    if ($this->is_zero) {
        # work around Math::BigInt bug rt.cpan.org #61543
        return $this->undefined if 0 >  $exp;
        return $this->_NEW(1)   if 0 == $exp;
        return $this;
    }
    my $p = $this->residue->copy->bmodpow($exp, $this->modulus);
    return $this->undefined if $p->is_nan;
    return $this->_NEW($p);
}

sub _INV {
    my ($this) = @_;
    my $i = $this->residue->copy->bmodinv($this->modulus);
    return $this->undefined if $i->is_nan;
    return $this->_NEW($i);
}

sub _NEW {
    my ($this, $int, $modulus) = @_;
    my $class = ref $this;
    if ($class) {
        $modulus = $this->modulus;
    }
    else {
        $class = $this;
    }
    foreach my $arg ($int, $modulus) {
        if (!ref($arg) || !$arg->isa('Math::BigInt')) {
            $arg = Math::BigInt->new($arg);
        }
    }
    return bless [$int % $modulus, $modulus], $class;
}

sub _NEW2 {
    my ($this, $int, $modulus) = @_;
    my $class = ref $this;
    if ($class) {
        $modulus = $this->modulus;
    }
    else {
        $class = $this;
    }
    foreach my $arg ($int, $modulus) {
        if (!ref($arg) || !$arg->isa('Math::BigInt')) {
            $arg = Math::BigInt->new($arg);
        }
    }
    my ($quotient, $remainder);
    if (_ISSUE_CPAN_RT79060 && $int->is_neg) {
        $remainder = $int % $modulus;
        $quotient = ($int - $remainder) / $modulus;
    }
    else {
        ($quotient, $remainder) = $int->copy->bdiv($modulus);
    }
    return ($quotient, bless [$remainder, $modulus], $class);
}

sub residue {
    my ($this) = @_;
    return $this->[F_RESIDUE];
}

sub modulus {
    my ($this) = @_;
    return $this->[F_MODULUS];
}

1;

__END__