php模拟js函数unescape的函数代码

function unescape($str)
{
$ret = '';
$len = strlen($str);
 
for ($i = 0; $i >6)).chr(0x80|($val&0x3f));
else $ret .= chr(0xe0|($val>>12)).chr(0x80|(($val>>6)&0x3f)).chr(0x80|($val&0x3f));
 
$i += 5;
}
else if ($str[$i] == '%')
{
$ret .= urldecode(substr($str, $i, 3));
$i += 2;
}
else $ret .= $str[$i];
}
return $ret;
}