Ziv-Lempel encoding with multi-bit flags

Abstract

LZ77 and more recently LZSS text compression use one-bit flags to identify a following pointer or literal. This paper investigates the use of multi-bit flags to allow a greater variety of entities in the compressed data stream. Two approaches are described. The first uses flags of 2 or 3 bits with operands constrained to be 1, 2 or 3 bytes long. The other codes entirely in units of 2 or 3 bits (instead of the more usual single bits). Both methods are shown to yield compressors of good performance.<>