Patent ID: 11868615
Assignee: KIOXIA CORPORATION
Field: Computer technology (Electrical engineering)
Classification: CPC G  H | IPC G  H

Claim 7:
8. A control method of controlling a compression device,
the compression device comprising:
a first storage unit configured to include first storage areas that each store a dictionary address corresponding to a piece of dictionary data and that each have a first storage area address which matches a hash value; and
a second storage unit configured to include second storage areas that each store data and that each have an associated address which matches the dictionary address stored in one of the first storage areas,

the control method comprising:
determining a first hash function that changes depending on at least part of first data;
calculating a first hash value of at least part of second data by using the determined first hash function, the second data being a part of the first data;
acquiring third data from a third storage area of the second storage areas, wherein the third storage area has the associated address that matches the dictionary address that is stored in a fourth storage area of the first storage areas, and the fourth storage area has the first storage area address that matches the calculated first hash value; and
comparing the second data with the third data to acquire a length of a matching portion between the second data and the third data, wherein

the first data includes n-byte data comprised of one or more data portions,
each of the one or more data portions has a length of m bits,
n is an integer of one or more,
m is an integer of two or more,
the control method comprises:
calculating a first ratio of bits which are 0 among one or more i-th bits that are each included in one of the one or more data portions, or a second ratio of bits which are 1 among the one or more i-th bits;
determining the first hash function based on the first ratio or the second ratio; and acquiring encoded data by performing entropy encoding on a combination of the dictionary address stored in the fourth storage area and the length of the matching portion, and

i is an integer of zero or more and less than m.