| 1 |
lars |
1 |
<?php
|
|
|
2 |
// +----------------------------------------------------------------------+
|
|
|
3 |
// | PHP Version 4 |
|
|
|
4 |
// +----------------------------------------------------------------------+
|
|
|
5 |
// | Copyright (c) 1997-2004 The PHP Group |
|
|
|
6 |
// +----------------------------------------------------------------------+
|
|
|
7 |
// | This source file is subject to version 3.0 of the PHP license, |
|
|
|
8 |
// | that is bundled with this package in the file LICENSE, and is |
|
|
|
9 |
// | available at through the world-wide-web at |
|
|
|
10 |
// | http://www.php.net/license/3_0.txt. |
|
|
|
11 |
// | If you did not receive a copy of the PHP license and are unable to |
|
|
|
12 |
// | obtain it through the world-wide-web, please send a note to |
|
|
|
13 |
// | license@php.net so we can mail you a copy immediately. |
|
|
|
14 |
// +----------------------------------------------------------------------+
|
|
|
15 |
// | Authors: Aidan Lister <aidan@php.net> |
|
|
|
16 |
// +----------------------------------------------------------------------+
|
|
|
17 |
//
|
|
|
18 |
// $Id: bcpowmod.php,v 1.2 2005/11/22 20:24:45 aidan Exp $
|
|
|
19 |
|
|
|
20 |
|
|
|
21 |
/**
|
|
|
22 |
* Replace bcpowmod()
|
|
|
23 |
*
|
|
|
24 |
* @category PHP
|
|
|
25 |
* @package PHP_Compat
|
|
|
26 |
* @link http://php.net/function.bcpowmod
|
|
|
27 |
* @author Sara Golemon <pollita@php.net>
|
|
|
28 |
* @version $Revision: 1.2 $
|
|
|
29 |
* @since PHP 5.0.0
|
|
|
30 |
* @require PHP 4.0.0 (user_error)
|
|
|
31 |
*/
|
|
|
32 |
if (!function_exists('bcpowmod')) {
|
|
|
33 |
function bcpowmod($x, $y, $modulus, $scale)
|
|
|
34 |
{
|
|
|
35 |
// Sanity check
|
|
|
36 |
if (!is_scalar($x)) {
|
|
|
37 |
user_error('bcpowmod() expects parameter 1 to be string, ' .
|
|
|
38 |
gettype($x) . ' given', E_USER_WARNING);
|
|
|
39 |
return false;
|
|
|
40 |
}
|
|
|
41 |
|
|
|
42 |
if (!is_scalar($y)) {
|
|
|
43 |
user_error('bcpowmod() expects parameter 2 to be string, ' .
|
|
|
44 |
gettype($y) . ' given', E_USER_WARNING);
|
|
|
45 |
return false;
|
|
|
46 |
}
|
|
|
47 |
|
|
|
48 |
if (!is_scalar($modulus)) {
|
|
|
49 |
user_error('bcpowmod() expects parameter 3 to be string, ' .
|
|
|
50 |
gettype($modulus) . ' given', E_USER_WARNING);
|
|
|
51 |
return false;
|
|
|
52 |
}
|
|
|
53 |
|
|
|
54 |
if (!is_scalar($scale)) {
|
|
|
55 |
user_error('bcpowmod() expects parameter 4 to be integer, ' .
|
|
|
56 |
gettype($scale) . ' given', E_USER_WARNING);
|
|
|
57 |
return false;
|
|
|
58 |
}
|
|
|
59 |
|
|
|
60 |
$t = '1';
|
|
|
61 |
while (bccomp($y, '0')) {
|
|
|
62 |
if (bccomp(bcmod($y, '2'), '0')) {
|
|
|
63 |
$t = bcmod(bcmul($t, $x), $modulus);
|
|
|
64 |
$y = bcsub($y, '1');
|
|
|
65 |
}
|
|
|
66 |
|
|
|
67 |
$x = bcmod(bcmul($x, $x), $modulus);
|
|
|
68 |
$y = bcdiv($y, '2');
|
|
|
69 |
}
|
|
|
70 |
|
|
|
71 |
return $t;
|
|
|
72 |
}
|
|
|
73 |
}
|
|
|
74 |
|
|
|
75 |
?>
|