Data decompressor for use with a data compressor implemented with limited length character tables and compact string codes

摘要

A decompressor recovers and outputs a stream of data characters corresponding to an input stream of compressed codes. The decompressor includes a dictionary that stores strings of data characters having respective codes associated therewith. A currently received compressed code accesses the dictionary to recover a string and the decompressor outputs the characters of the recovered string so as to provide the output stream of data characters. An extended string is inserted into the dictionary that comprises the string corresponding to the previously received code extended by the first character of the recovered string. A code is assigned to the stored extended string. The decompressor maintains counts of inserted extended strings that have the same extension character for respective characters of the alphabet. The inserting of an extended string into the dictionary and the assigning of a code thereto are bypassed for an extended string having a particular extension character when the count of such strings attains an associated predetermined limit. Additionally, extended string insertion and code assignment are bypassed for an extended string having an extension character that is denoted as an excluded character.