DATA COMPRESSION APPARATUS AND METHOD

摘要

Apparatus and method for compression of a digital sequence. The compressed sequence may be buffered and a compression procedure altered depending on buffer usage. This altering may include changing the depth of searching for matches performed in linked lists depending on the amount of the sequence being buffered. An adjacent element can be found in a linked list using a pointer, and a match can also be found in a history buffer using the same pointer. Frequency values may be updated for symbols based on a sampled subset of the symbols, and a token may be derived, such as by Huffman encoding, for each symbol from the updated frequency values. A subsequence may be encoded using an offset referenced to an earlier match. An insert pointer and a check pointer into a history buffer may be maintained, and a determination can be made as to whether accessing the history buffer is valid based on these check pointers. The maximum amount of the history buffer in which accessing is valid may be set. Decompression of sequences is also presented.