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Method for compression of data using single pass LZSS and run-length encoding

United States Patent

5,701,125
December 23, 1997
View the Complete Patent at the US Patent & Trademark Office
Savannah River National Laboratory - Visit the Technology Transfer Website
A method used preferably with LZSS-based compression methods for compressing a stream of digital data. The method uses a run-length encoding scheme especially suited for data strings of identical data bytes having large run-lengths, such as data representing scanned images. The method reads an input data stream to determine the length of the data strings. Longer data strings are then encoded in one of two ways depending on the length of the string. For data strings having run-lengths less than 18 bytes, a cleared offset and the actual run-length are written to an output buffer and then a run byte is written to the output buffer. For data strings of 18 bytes or longer, a set offset and an encoded run-length are written to the output buffer and then a run byte is written to the output buffer. The encoded run-length is written in two parts obtained by dividing the run length by a factor of 255. The first of two parts of the encoded run-length is the quotient; the second part is the remainder. Data bytes that are not part of data strings of sufficient length are written directly to the output buffer.
Berlin; Gary J. (Beech Island, SC)
The United States of America as represented by the United States (Washington, DC)
08/ 261,225
June 15, 1994
The United States Government has rights in this invention pursuant to Contract No. DE-AC09-89SR18035 between the U.S. Department of Energy and Westinghouse Savannah River Company.