PDU Converter

<!DOCTYPE HTML>
<html>
<head>
<title>PDU Converter</title>
<style>
* { font-family:Calibri }
fieldset { margin-bottom: 15px; padding: 10px }
legend { padding: 0px 3px; font-weight: bold; font-variant: small-caps }
select { width: 254px }
input[type=submit] { width: 170px; padding: 10px }
</style>
</head>

<body>

<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="get">
  <fieldset>
    <legend>Enter Text for encode to PDU format</legend>
    <textarea name="inputtext" cols="40" rows="5">
    <?php
        if (isset($_GET['inputtext']) && $_GET['inputtext'])
        {
            echo $_GET['inputtext'];
        }
    ?>
    </textarea>
    <textarea name="Text1" cols="40" rows="5" ... >
    <?php
        if (isset($_GET['inputtext']) && $_GET['inputtext'])
        {
            encodePDU($_GET['inputtext']);
        }
    ?>
    </textarea>
  </fieldset>
  <input type="submit" value="Encode">
</form>
<br>
<br>
<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="get">
  <fieldset>
    <legend>Enter PDU for decode to Text format</legend>
    <textarea name="inputpdu" cols="40" rows="5">
    <?php
        if (isset($_GET['inputpdu']) && $_GET['inputpdu'])
        {
            echo $_GET['inputpdu'];
        }
    ?>
    </textarea>
    <textarea name="Text2" cols="40" rows="5" ... >
    <?php
        if (isset($_GET['inputpdu']) && $_GET['inputpdu'])
        {
            decodePDU($_GET['inputpdu']);
        }
    ?>
    </textarea>
  </fieldset>
  <input type="submit" value="Decode">
</form>


</body>
</html>

<?php
function decodePDU($in) {
  $b = 0; $d = 0;
  $out = "";
  foreach (str_split($in, 2) as $ss) {
    $byte = hexdec($ss);
    $c = (($byte & ((1 << 7-$d)-1)) << $d) | $b;
    $b = $byte >> (7-$d);
    $out .= chr($c);
    $d++;
    if ($d == 7) {
      $out .= chr($b);
      $d = 0; $b = 0;
    }
  }
  echo $out;
}

function encodePDU($in) {
  $out = "";
  for ($i = 0; $i < strlen($in); $i++) {
    $t = $i%8+1;
    if ($t == 8)
      continue;
    $c = ord($in[$i])>>($i%8);
    $oc = $c;
    $b = ord($in[$i+1]) & ((1 << $t)-1);
    $c = ($b << (8-$t)) | $c;
    $out .= strtoupper(str_pad(dechex($c), 2, '0', STR_PAD_LEFT));
  }
  echo $out;
}
?>