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   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: bcinvert.php,v 1.2 2005/11/22 20:24:45 aidan Exp $

  19  
  20  
  21  /**

  22   * Replace bcinvert()

  23   *

  24   * @category    PHP

  25   * @package     PHP_Compat

  26   * @link        http://php.net/function.bcinvert

  27   * @author      Sara Golemon <pollita@php.net>

  28   * @version     $Revision: 1.2 $

  29   * @since       PHP 5.2.0

  30   * @require     PHP 4.0.4 (call_user_func_array)

  31   */
  32  if (!function_exists('bcinvert')) {
  33      function bcinvert($a, $n)
  34      {
  35          // Sanity check

  36          if (!is_scalar($a)) {
  37              user_error('bcinvert() expects parameter 1 to be string, ' .
  38                  gettype($a) . ' given', E_USER_WARNING);
  39              return false;
  40          }
  41  
  42          if (!is_scalar($n)) {
  43              user_error('bcinvert() expects parameter 2 to be string, ' .
  44                  gettype($n) . ' given', E_USER_WARNING);
  45              return false;
  46          }
  47          
  48          $u1 = $v2 = '1';
  49          $u2 = $v1 = '0';
  50          $u3 = $n;
  51          $v3 = $a;
  52  
  53          while (bccomp($v3, '0')) {
  54              $q0 = bcdiv($u3, $v3);
  55              $t1 = bcsub($u1, bcmul($q0, $v1));
  56              $t2 = bcsub($u2, bcmul($q0, $v2));
  57              $t3 = bcsub($u3, bcmul($q0, $v3));
  58  
  59              $u1 = $v1;
  60              $u2 = $v2;
  61              $u3 = $v3;
  62  
  63              $v1 = $t1;
  64              $v2 = $t2;
  65              $v3 = $t3;
  66          }
  67  
  68          if (bccomp($u2, '0') < 0) {
  69              return bcadd($u2, $n);
  70          } else {
  71              return bcmod($u2, $n);
  72          }
  73      }
  74  }
  75  
  76  ?>