use warnings;
use strict;
use Encode qw/decode/;
use Data::Dump;

dd decode('UTF-16-BE', "\xD8\x3D\xDD\xFA", Encode::FB_QUIET|Encode::LEAVE_SRC);
dd decode('UTF-16-BE', "\x3D\xDD\xFA", Encode::FB_QUIET|Encode::LEAVE_SRC);
dd decode('UTF-16-BE', "\x3D\xDD\xFA", sub{ sprintf "<U+%04X>", shift });

dd decode('UTF-16-LE', "\x3D\xD8\xFA\xDD", Encode::FB_QUIET|Encode::LEAVE_SRC);
dd decode('UTF-16-LE', "\xD8\xFA\xDD", Encode::FB_QUIET|Encode::LEAVE_SRC);
dd decode('UTF-16-LE', "\xD8\xFA\xDD", sub{ sprintf "<U+%04X>", shift });

__END__

"\x{1F5FA}"
"\x{3DDD}"
"\x{3DDD}"
"\x{1F5FA}"
"\x{FAD8}"
"\x{FAD8}"