<?php

/***
 * Purpose : generation checksum code for matching request checksum
 * 
 * @author Rohit Kashyap
 * @since 07/05/2020 >> dd/mm/yyyy
 * @version 0.1
 * @copyright Copyright (C) 2020 Graposs Edutech Ltd. All rights reserved.
 * @license Graposs Edutech Ltd.
 */

/***
 * function return checksum value
 */
function adler32($data) {
 $a = 1; $b = 0; $len = strlen($data);
 for ($index = 0; $index < $len; ++$index) {
 $a = ($a + ord($data[$index])) % 65521;
 $b = ($b + $a) % 65521;
 }
 return ($b << 16) | $a; 
}