Abstract: An apparatus and method for converting an input data character stream into a variable length encoded data stream in a data compression system. A sliding window data compression algorithm is combined with Huffman encoding on the strings and raw bytes. The Huffman table, in a compressed form, is prepended to the encoded output data. The Huffman codes representing the shortest strings encode both the string length and part of the string offset. Assigning Huffman codes to represent the combined length and offset allows the use of a smaller sliding window size without sacrificing compression ratio. The smaller window size allows implementations in software and hardware to minimize memory usage, thus reducing cost.

Abstract: An apparatus and method are disclosed for converting an input data character stream into a variable length encoded data stream in a data compression system. The data compression system includes a history array. The history array has a plurality of entries and each entry of the history array is for storing a portion of the input data stream. The method for converting the input data character stream includes the following steps. Performing a search in a history array for the longest data string which matches the input data string. If the matching data string is found within the history buffer, the next step includes encoding the longest matching data string found by appending to the encoded data stream a tag indicating the longest matching data string was found and a string substitution code.

Abstract: An apparatus and method are disclosed for converting an input data character stream into a variable length encoded data stream in a data compression system. The data compression system includes a history array. The history array has a plurality of entries and each entry of the history array is for storing a portion of the input data stream. The method for converting the input data character stream includes the following steps. Performing a search in a history array for the longest data string which matches the input data string. If the matching data string is found within the history buffer, the next step includes encoding the longest matching data string found by appending to the encoded data stream a tag indicating the longest matching data string was found and a string substitution code.

Abstract: A data compression device driver compresses and decompresses files on a disk drive in a computer system when a user copies files from a drive letter assigned to the disk drive to a drive letter assigned to the data compression device driver. Drive parameter blocks for the disk drive and for the data compression device driver contain the assigned drive letter, disk geometry information, a rebuild flag, and a pointer to the device driver. A swapping means swaps the device driver pointers in the drive parameter blocks corresponding to the disk drive and the data compression device driver. From then on, compressed data files may be accessed transparently by using the drive letter which was originally assigned to the disk drive before swapping, which now refers to the data compression device driver.

Abstract: An apparatus and method as disclosed for converting an input data character stream into a variable length encoded data stream in a data compression system. The data compression system includes a history array means. The history array means has a plurality of entries and each entry of the history array means is for storing a portion of the input data stream. The method for converting the input data character stream includes the following steps. Performing a search in a history array means for the longest data string which matches the input data string. If the matching data string is found within the history buffer means, the next step includes encoding the longest matching data string found by appending to the encoded data stream a tag indicating the longest matching data string was found and a string substitution code.

Abstract: An apparatus and/or method for generating parity digits of digital information (data) in a digital communication system is disclosed. The communication system (8) is for transferring a plurality of data intervals from an originating data source (12) to a data sink (13). Each data interval comprises one or more blocks of data and each block contains one or more bytes of data. The communication system (8) includes a temporary storage means (24) for holding the data for a limited period. Included are means for transferring (14, 40) one or more data intervals from the data source (12) to the temporary storage means (24) and means for transferring (22, 40) one of the data intervals from the temporary storage means (24) to the data sink (13) including means for calculating (72) error correcting code words associated with each data interval and means for storing (16) the error correcting code words for further processing.