Method and apparatus for adaptive data compression

摘要

The present invention relates to data compression systems and methods wherein text can be compressed by encoding repetitions of blocks of characters, or through a straight encoding scheme that converts eight-bit character values to four-bit character values by eliminating values for characters that are not valid word-starting characters or valid next-letter characters for a given preceding letter. Block compression is accomplished through the use of data structures that track the successive occurrence of valid block-repetition starting characters, and their lengths. Repeat-relative block compression is accomplished by detecting character sequences that can be expressed as the value of a previously-occurring character sequence plus or minus an offset.