$t = unpack('C', $foo);
if ($t == 0) { $v = unpack('C', substr($foo, 1)) }
elsif ($t == 1) { $v = unpack('S', substr($foo, 1)) }
elsif ($t == 2) { $v = unpack('L', substr($foo, 1)) }
elsif ($t == 3) { $v = unpack('Z*', substr($foo, 1)) }