calculate guid

<?php

//echo "".PHP_INT_MAX."<br>";

date_default_timezone_set('Europe/London');

include "includes/header.php";

if ((!isset($_POST['steamid']) && !isset($_POST['submitok'])) || $_POST['steamid'] == "")
{
    echo '<div style="float:left;padding:20px;">';
    echo '  <form method="post" action="lookup.php" name="myform">
                <p style="width:100%;padding-top:5px;padding-bottom:5px">
                    <label>Steam64ID:</label><br>
                    <input type="text" name="steamid" size=45 id="steamid"></input>
                    <input type="hidden" name="submitok" value="true">
                    <input type="submit">
                </p>
            </form>
            <script language="Javascript"  type="text/javascript"><!--
            document.myform.steamID.focus();
            //-->
            </script>
        </div>';
}
else
{
    $steamid = $_POST['steamid'];
    $guid = getGUID($steamid);

    $temp = '';
    for ($i = 0; $i < 8; $i++) {
            $temp .= chr($steamid & 0xFF);
            $steamid >>= 8;
    }
    $return = md5('BE' . $temp);

    echo '<div style="float:left;padding:20px;">';
    echo "<hr>steam64ID: ".$_POST['steamid']."<br>guid: $return<hr>";
    echo '</div>';

}

function A2S($steamid)
{
    return bcadd($steamid,'76561197960265728');
}

function S2A($steamid)
{
    return bcsub($steamid,'76561197960265728');
}

function getGUID($steamid)
{
    $temp = '';
    for ($i = 0; $i < 8; $i++) {
            $temp .= chr($steamid & 0xFF);
            $steamid >>= 8;
    }
    $return = md5('BE' . $temp);
}

?>