Viewing file:  bcpowmod.php (2.74 KB) -rw-rw-rw-
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<?php
// +----------------------------------------------------------------------+
// | PHP Version 4 |
// +----------------------------------------------------------------------+
// | Copyright (c) 1997-2004 The PHP Group |
// +----------------------------------------------------------------------+
// | This source file is subject to version 3.0 of the PHP license, |
// | that is bundled with this package in the file LICENSE, and is |
// | available at through the world-wide-web at |
// | http://www.php.net/license/3_0.txt. |
// | If you did not receive a copy of the PHP license and are unable to |
// | obtain it through the world-wide-web, please send a note to |
// | license@php.net so we can mail you a copy immediately. |
// +----------------------------------------------------------------------+
// | Authors: Aidan Lister <aidan@php.net> |
// +----------------------------------------------------------------------+
//
// $Id: bcpowmod.php,v 1.2 2005/11/22 20:24:45 aidan Exp $
/**
* Replace bcpowmod()
*
* @category PHP
* @package PHP_Compat
* @link http://php.net/function.bcpowmod
* @author Sara Golemon <pollita@php.net>
* @version $Revision: 1.2 $
* @since PHP 5.0.0
* @require PHP 4.0.0 (user_error)
*/
if (!function_exists('bcpowmod')) {
function bcpowmod($x, $y, $modulus, $scale)
{
// Sanity check
if (!is_scalar($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;
}
}
?>
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