Abstract: Data compression systems, methods, and computer program products are disclosed. For each successive input word of an input stream, it is determined whether the input word matches an entry in a lookback table. The lookback table is updated in response to the input word. Input words may be of a number of data types, including zero runs and full or partial matches with an entry in the lookback table. A codeword is generated by entropy encoding a data type corresponding to the input word. The lookback table may be indexed by the position of the input word in the input stream.

Abstract: A multi-pass compression iteratively removes combinations of bits from locations in each word of a cache line of an uncompressed data stream. For each combination of removed bits, the remaining bits in the word values of the cache line are analyzed to generate a compression score. A highest compression score triggers the building of a dictionary from the remaining bits in the word values of the cache line. After a dictionary is built, the method may continue iteratively to create subsequent dictionaries from the words that remain uncompressed in the cache line. To decompress a word, a first bit section of the compressed word is used to identify a dictionary that is then queried for bits indexed in a second bit section of the compressed word. The uncompressed word is reconstructed by interleaving the queried bits with the removed combination of bits from a third bit section of the word.

Abstract: A multi-pass compression iteratively removes combinations of bits from locations in each word of a cache line of an uncompressed data stream. For each combination of removed bits, the remaining bits in the word values of the cache line are analyzed to generate a compression score. A highest compression score triggers the building of a dictionary from the remaining bits in the word values of the cache line. After a dictionary is built, the method may continue iteratively to create subsequent dictionaries from the words that remain uncompressed in the cache line. To decompress a word, a first bit section of the compressed word is used to identify a dictionary that is then queried for bits indexed in a second bit section of the compressed word. The uncompressed word is reconstructed by interleaving the queried bits with the removed combination of bits from a third bit section of the word.

Abstract: Lempel-Ziv (LZ)-based data compression employing implicit variable-length distance coding is disclosed. Distances in LZ-based data compression length and distance blocks are implicit variable-length encoded during data compression to avoid padding encoded distances with extra bits (e.g., trailing 0's) that require fewer bits for storage than the number of bits needed to store maximum distance length. This reduces distance bit lengths in compressed output data to further reduce data size. During data compression, a distance table is generated that contains entries each having an assigned base and a number of extra bits to be read in compressed data during data decompression. In this manner, during data decompression, the entries in the distance table can be consulted to determine the number of bits in the variable-encoded distance in the compressed data to be read since the encoded distances can be encoded in the compressed data in fewer bits and without bit padding.