A device compresses a mapping table in a flash translation layer of a SSD. The mapping table includes mappings between Logical Page Numbers (LPNs) and Physical Page Numbers (PPNs). A base PPN table stores at least one entry including a base PPN common to multiple LPNs. A PPN offset table stores an offset for each mapping. A set of hash functions are duplicated for each entry in the base PPN table. A bit extension unit adds bits to the respective offset in the PPN offset table to provide an extended offset bit. A hash calculator calculates a hash value using the base PPN and one of the hash functions corresponding to the base PPN. An exclusive OR unit outputs a new PNN for each of different LPNs, including the multiple LPNs, by applying an exclusive OR operation to the hash value and the extended offset bit.