Method and apparatus for compression and decompression of data

摘要

A coding is carried out by designating the reference number of a partial sequence having the maximum length coincidence from the coded partial sequences registered in a dictionary with regard to a received character sequence, designating a new reference number to a partial sequence which is obtained by adding one character to a reference number obtained as a code word, and registering the new reference number designated partial sequence in the dictionary. A decoding is carried out by searching partial sequences registered in the dictionary using a code word represented by the reference number of the partial sequence, decompressing the original partial sequence, designating a new reference number to a partial sequence which is obtained by adding the beginning character of the currently decompressed partial sequence to the previously processed code word, and registering the new reference number designated partial sequence in the dictionary. According to the invention, the following steps are provided :
constituting a registration dictionary by registering a substantial partial sequence for each of the last characters of the first partial sequence of successive two partial sequences or each of the groups based on the last character;designating a registration number of a partial sequence to be registered for each of the last characters or each of groups based on the last character; andconstituting a code word of partial sequence to be coded based on the designated registration number.