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