Patent ID: 11876542
Assignee: UNIVERSITY OF TSUKUBA
Field: Basic communication processes (Electrical engineering)
Classification: CPC H  G | IPC G  H

Claim 0:
1. A data compression and decompression method comprising:
causing a compression apparatus to perform processing of registering a symbol, which is input, in one of a plurality of entries in a case where the symbol is not registered in a first table having the plurality of entries and outputting the symbol and index data indicating non-compression, and processing of outputting index data indicating compression and positional information indicating a position of the entry having the symbol registered therein and having a size smaller than a size of the symbol in a case where the symbol has been registered in the first table;
causing a decompression apparatus to perform processing of registering the symbol in a second table having the same data structure as that of the first table by the same method as a method of registering the symbol in the compression apparatus and outputting the symbol in a case where the index data indicating non-compression and the symbol have been received, and processing of reading and outputting the symbol registered in an entry in the second table indicated by the positional information in a case where the index data indicating compression and the positional information have been received;
causing the compression apparatus to output positional information of an entry in use in the first table which is represented by a first number of bits, which is a least number of bits capable of representing the positional information, based on information indicating usage conditions of the plurality of entries of the first table in a case where the index data indicating compression and the positional information are output; and
causing the decompression apparatus to extract positional information of an entry in use in the second table from a bit sequence which is transmitted from the compression apparatus and input to the decompression apparatus using a second number of bits which is a least number of bits capable of representing the positional information in a case where the decompression apparatus has received the index data indicating non-compression and the symbol and has registered the symbol in the second table, the second number of bits being calculated by the same calculation method as a method of calculating the first number of bits based on information indicating usage conditions of the plurality of entries of the second table.