Abstract: Described above is a two-pass method of compressing a data input stream to create a compressed data output stream. The method includes a step of sequentially examining data elements and strings of data elements of the data input stream in a first compression pass using a sliding window compression scheme to find literal data elements and pairs of length and displacement values. The first compression pass includes: coding the literal data elements and the length values with a first minimum redundancy coding tree; coding the displacement values with a second minimum redundancy coding tree; and adding the coded literal data elements, length values, and displacement values to a single data buffer. The method also includes a second compression pass that is performed whenever the single data buffer reaches a predefined capacity.

Abstract: A method and system for maintaining a binary tree of pointers to a stream of data and for searching same. A novel binary tree is created by a search engine in which the nodes associated with strings in the data stream which are closer to the current data stream position are nearer the root of the tree than nodes associated with strings which are farther. As the current position in the stream is advanced, the search engine inserts a new node to the tree for that position as the root node. The tree is then restructured based on the relative value of the strings of each node while preserving the temporal order of the tree such that strings nearer the current position are associated with nodes which are closer to the root. The tree is ideal for searching data for LZ77-based data compression, since a single traversal of the tree returns the longest match length with the smallest offset.