<?
    $data = preg_replace("/[^01]/","",$data);

    function dodata($data){
        $out = '';
        while($data){
            $block = substr($data,0,8);
            $data = substr($data,8);
            $out .= chr(bindec($block));
        }
        return $out;
    }

?>

<? if ($data){ ?>
    Message: "<?=dodata($data)?>"<br>
    <br>
<? } ?>
<form method="post">
<textarea name="data" wrap="virtual" col="30" rows="10"></textarea><br>
<input type="submit" value="go">
</form>