Ion - Base64 coder

(source)
<?PHP
ini_set('display_errors', 0);
echo '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">';
echo '<html><head><title>Ion - Base64 coder</title></head><body>';

b64( htmlentities( $_POST['txtb64'], ENT_QUOTES ), htmlentities( $_POST['butb64'], ENT_QUOTES ) );

echo '<font size="1" face="courier new"><br><br>(<a href="?action=source">source</a>)</font><br><br>';
echo '</body></html>';

function b64($txt, $but)
{
    if( $but == "Encode")
        $b64 = base64_encode( $txt );
    else
        $b64 = base64_decode( $txt );

    echo '<form method="post" action=""><table width="400px" border="0" cellpadding="0" cellspacing="0"><tr><td><textarea name="txtb64" rows="2" cols="20" id="txtb64" style="height:250px;width:400px;">'.$b64.'</textarea><br><br></td></tr>';
    echo '</tr><td align="center"><input type="submit" name="butb64" value="Encode" />&nbsp;<input type="submit" name="butb64" value="Decode" /></td></tr></table></form>';
}

// View Source
if( htmlentities( $_GET['action'], ENT_QUOTES ) == 'source' )
    highlight_file( './b64.php' );

?>