We use a hash encoder to map file names to numeral
values, like the hash table index in Java language, which
ensures that a single word or phrase can be translated into
one unique result. However, due to the hash code may
possibly be negative, the output of the encoder need to do an
“AND” operation with 0x7FFFFFFF ensuring that it is
positive after conversion. When searching files, taking
picture file for instance, the hash function works as follows: