Method and apparatus for compressing and decompressing data

摘要

A data processing system having a compression and decompression apparatus based on the Lempel-Ziv algorithm. The compression apparatus includes a history RAM unit for receiving and storing one or more data elements and a coding unit for determining whether received data elements previously have been stored in the history RAM unit and are a candidate for compression. If a received data element matches at least one of the stored data elements, an address of the matching stored data element is generated. The compression apparatus generates a compression token comprising an identification of whether a data element is compressed, the length of the coded data within a plurality of predetermined data length categories and an address. The decompression apparatus also includes a history RAM unit for storing received data elements and includes a circuit for receiving a compression token and determining- the storage addresses of the next data element from the length and address information contained in the token. The apparatus can identify the next address at high speed by a parallel processing using the predetermined length categories. <IMAGE>