Base64 EnDecode

<?php {
echo "<br><br><center><title>BASE64 | AZZATSSINS</title><body bgcolor=maroon><font color=silver><b>AZZATSSIN'S</b></font><br><div id=result> <nobr><b><span class='b7'>O=:[ ENCODE</span> <span class='b8'>DECODE ]:=O</span></b></nobr><br/><br/>
<form method='post'><table class=tbl>
<tr><td>Method : <select name='typed' style='color:red; background-color:black; border:1px solid #666;'>
<option>Encode</option><option>Decode</decode></select> </td></tr>
<tr><td>TYPE : <select name='typenc' style='color:red; background-color:black; border:1px solid #666;'>
<option>GZINFLATE</option><option>GZUNCOMPRESS</option><option>STR_ROT13</option></tr>
</td>
<tr><td>
<textarea spellcheck='false' style='color:#FF0000;background-color:#000000' cols='80' rows='25' name='php_content'></textarea></tr>
</td></table><hr/><input style='color:#FF0000;background-color:#000000' type='submit' value='   >>   ' /><br /><hr /><br /></form></div>";

$meth_d=$_POST['typed'];
$typ_d=$_POST['typenc'];
$c_ntent=$_POST['php_content'];
$c_ntent=$c_ntent;
switch($meth_d)
{
case "Encode":
switch($typ_d)
{
case "GZINFLATE":
$res_t=base64_encode(gzdeflate(trim(stripslashes($c_ntent.' '),'<?php, ?>'),9));
$res_t="<?php eval(gzinflate(base64_decode(\"$res_t\"))); ?>";
break;
case "GZUNCOMPRESS":
$res_t=base64_encode(gzcompress(trim(stripslashes($c_ntent.' '),'<?php, ?>'),9));
$res_t="<?php eval(gzuncompress(base64_decode(\"$res_t\"))); ?>";
break;
case "STR_ROT13":
$res_t=trim(stripslashes($c_ntent.' '),'<?php, ?>');
$res_t=base64_encode(str_rot13($res_t));
$res_t="<?php eval(str_rot13(base64_decode(\"$res_t\"))); ?>";
break;
}
break;
case "Decode":
switch($typ_d)
{
case "GZINFLATE":
$res_t=gzinflate(base64_decode($c_ntent));
break;
case "GZUNCOMPRESS":
$res_t=gzuncompress(base64_decode($c_ntent));
break;
case "STR_ROT13":
$res_t=str_rot13(base64_decode($c_ntent));
break;
}
break;
}
echo "<center><div id=result><textarea spellcheck='false' style='color:#FF0000;background-color:#000000' cols='80' rows='25'>".htmlspecialchars($res_t)."</textarea></center></div>";
}
?>