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<?php
// $Id: bcpowmod.php,v 1.1 2007/07/02 04:19:55 terrafrost Exp $
/**
* Replace bcpowmod()
*
* @category PHP
* @package PHP_Compat
* @license LGPL - http://www.gnu.org/licenses/lgpl.html
* @copyright 2004-2007 Aidan Lister <aidan@php.net>, Arpad Ray <arpad@php.net>
* @link http://php.net/function.bcpowmod
* @author Sara Golemon <pollita@php.net>
* @version $Revision: 1.1 $
* @since PHP 5.0.0
* @require PHP 4.0.0 (user_error)
*/
function php_compat_bcpowmod($x, $y, $modulus, $scale = 0)
{
// Sanity check
if (!is_scalar($x)) {
user_error('bcpowmod() expects parameter 1 to be string, ' .
gettype($x) . ' given', E_USER_WARNING);
return false;
}
if (!is_scalar($y)) {
user_error('bcpowmod() expects parameter 2 to be string, ' .
gettype($y) . ' given', E_USER_WARNING);
return false;
}
if (!is_scalar($modulus)) {
user_error('bcpowmod() expects parameter 3 to be string, ' .
gettype($modulus) . ' given', E_USER_WARNING);
return false;
}
if (!is_scalar($scale)) {
user_error('bcpowmod() expects parameter 4 to be integer, ' .
gettype($scale) . ' given', E_USER_WARNING);
return false;
}
$t = '1';
while (bccomp($y, '0')) {
if (bccomp(bcmod($y, '2'), '0')) {
$t = bcmod(bcmul($t, $x), $modulus);
$y = bcsub($y, '1');
}
$x = bcmod(bcmul($x, $x), $modulus);
$y = bcdiv($y, '2');
}
return $t;
}
// Define
if (!function_exists('bcpowmod')) {
function bcpowmod($x, $y, $modulus, $scale = 0)
{
return php_compat_bcpowmod($x, $y, $modulus, $scale);
}
}
?>
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