Fast data compressor with direct lookup table indexing into history buffer

Patent 5155484 Issued on October 13, 1992. Estimated Expiration Date:

September 13, 2011. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

Data compression system for successively applying at least two data compression methods to an input data stream
Patent #: 4988998
Issued on: 01/29/1991
Inventor: O'Brien

Data compression apparatus and method
Patent #: 5016009
Issued on: 05/14/1991
Inventor: Whiting, et al.

Apparatus and method for very high data rate-compression incorporating lossless data compression and expansion utilizing a hashing technique Patent #: 5049881
Issued on: 09/17/1991
Inventor: Gibson, et al.

Inventor

Chambers, IV, Lloyd L.

Assignee

Salient Software, Inc.

Application

No. 759226 filed on 09/13/1991

US Classes:

341/55, Substituting specified bit combinations for other prescribed bit combinations341/106Coding by table look-up techniques

Examiners

Primary: Logan, Sharon D.

Attorney, Agent or Firm

Fliesler, Dubb, Meyer & Lovejoy

International Class

H03M 007/42

Abstract

A cooperating data compressor, compressed data format, and data decompressor. The compressor compresses an input data block (HB) to a compressed data block having the format. The decompressor decompresses the compressed data block to restore the original data block. The compressor has a direct lookup table (DLT) of 28×N entries, each indexable by N bytes at a current HB location and identifying a target HB location. The compressor determines whether a target string at the target HB location matches a current string at the current HB location. If they do not match, the compressor outputs a literal representing a datum at the current location. If they match, the compressor outputs a vector from the current location to the target string. Compression speed is maximized by the direct addressing of the DLT by the current N bytes in the HB. Decompression speed is maximized by state machine operation according to literal/vector indicators, special case string length codes, and special case offset codes in the compressed data format.