--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/web/Zend/Validate/Barcode/Issn.php	Mon Dec 13 18:29:26 2010 +0100
@@ -0,0 +1,119 @@
+<?php
+/**
+ * Zend Framework
+ *
+ * LICENSE
+ *
+ * This source file is subject to the new BSD license that is bundled
+ * with this package in the file LICENSE.txt.
+ * It is also available through the world-wide-web at this URL:
+ * http://framework.zend.com/license/new-bsd
+ * If you did not receive a copy of the license and are unable to
+ * obtain it through the world-wide-web, please send an email
+ * to license@zend.com so we can send you a copy immediately.
+ *
+ * @category   Zend
+ * @package    Zend_Validate
+ * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)
+ * @license    http://framework.zend.com/license/new-bsd     New BSD License
+ * @version    $Id: Issn.php 20785 2010-01-31 09:43:03Z mikaelkael $
+ */
+
+/**
+ * @see Zend_Validate_Barcode_AdapterAbstract
+ */
+require_once 'Zend/Validate/Barcode/AdapterAbstract.php';
+
+/**
+ * @category   Zend
+ * @package    Zend_Validate
+ * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)
+ * @license    http://framework.zend.com/license/new-bsd     New BSD License
+ */
+class Zend_Validate_Barcode_Issn extends Zend_Validate_Barcode_AdapterAbstract
+{
+    /**
+     * Allowed barcode lengths
+     * @var integer
+     */
+    protected $_length = array(8, 13);
+
+    /**
+     * Allowed barcode characters
+     * @var string
+     */
+    protected $_characters = '0123456789X';
+
+    /**
+     * Checksum function
+     * @var string
+     */
+    protected $_checksum = '_gtin';
+
+    /**
+     * Allows X on length of 8 chars
+     *
+     * @param  string $value The barcode to check for allowed characters
+     * @return boolean
+     */
+    public function checkChars($value)
+    {
+        if (strlen($value) != 8) {
+            if (strpos($value, 'X') !== false) {
+                return false;
+            }
+        }
+
+        return parent::checkChars($value);
+    }
+
+    /**
+     * Validates the checksum
+     *
+     * @param  string $value The barcode to check the checksum for
+     * @return boolean
+     */
+    public function checksum($value)
+    {
+        if (strlen($value) == 8) {
+            $this->_checksum = '_issn';
+        } else {
+            $this->_checksum = '_gtin';
+        }
+
+        return parent::checksum($value);
+    }
+
+    /**
+     * Validates the checksum ()
+     * ISSN implementation (reversed mod11)
+     *
+     * @param  string $value The barcode to validate
+     * @return boolean
+     */
+    protected function _issn($value)
+    {
+        $checksum = substr($value, -1, 1);
+        $values   = str_split(substr($value, 0, -1));
+        $check    = 0;
+        $multi    = 8;
+        foreach($values as $token) {
+            if ($token == 'X') {
+                $token = 10;
+            }
+
+            $check += ($token * $multi);
+            --$multi;
+        }
+
+        $check %= 11;
+        $check  = 11 - $check;
+        if ($check == $checksum) {
+            return true;
+        } else if (($check == 10) && ($checksum == 'X')) {
+            return true;
+        }
+
+        return false;
+    }
+}