Decrypt Feistel Cipher in PostgreSQL

Decrypt Feistel Cipher in PostgreSQL

I updated a bunch of fields in my db using this Feistel Cipher. According
to the documentation, the cipher can be undone to get the original value.
How can I undo the values if need be?
Here is the original cipher function:
CREATE OR REPLACE FUNCTION pseudo_encrypt(VALUE int) returns bigint AS $$
DECLARE
l1 int;
l2 int;
r1 int;
r2 int;
i int:=0;
BEGIN
l1:= (VALUE >> 16) & 65535;
r1:= VALUE & 65535;
WHILE i < 3 LOOP
l2 := r1;
r2 := l1 # ((((1366.0 * r1 + 150889) % 714025) / 714025.0) * 32767)::int;
l1 := l2;
r1 := r2;
i := i + 1;
END LOOP;
RETURN ((l1::bigint << 16) + r1);
END;
$$ LANGUAGE plpgsql strict immutable;