DATA COMPRESSION AND RESTORATION METHOD AND DEVICE THEREFOR.

摘要

A data compression and restoration device which reads out a fed character string one character at a time and holds a present character substring being the coding object, and which refers to a character substring of maximum length matching with the present character substring from among the character substrings registered in the dictionary according to the relation to the last character of the preceding character substring and codes the longest match character part. The device also gives one new reference number to the present character substring which is generated newly by adding the next character to the longest match character string, and codes the same by registering it in the dictionary. The character substring registered in the dictionary by the code expressed by the reference number of the character substring is retrieved to restore the original character substring, and a new reference number is given to a character substring comprising a restored character string and the first character of the character string to be decoded next while decoding the character string by registering it in the dictionary. Thereby, the compressibility of data coding is improved.