public static function powmod($x, $y, $m)
{
switch (BigInt::support()) {
case 'gmp':
return gmp_powm($x, $y, $m);
case 'big_int':
return bi_powmod($x, $y, $m);
case 'bcmath':
return bcpowmod($x, $y, $m);
case '':
default:
return BigInt::_powmod($x, $y, $m);
}
}
