High-speed single-pass textual search processor for locating exact and inexact matches of a search pattern in a textual stream

摘要

A high speed search processor capable of performing a wide variety of search functions, including simple and complex searches, either within an entire text stream or within predefined fixed or sliding windows in the text stream. The processor is made up of multiple interconnected cells, each of which has a pattern register for storing part of a pattern to be searched for, a character register for storing a character of the data stream to be searched, a match register for storing a match value indicative of a match between the search pattern and the text stream, and match logic for modifying an incoming match value in accordance with conditions within the cell. The data stream and the search pattern are oppositely oriented, such that a first character of the search pattern is first encountered by a first character in the data stream, and the pattern is successively compared with an equal number of characters in the data stream as it is moved through the search pattern. The match logic includes means for detecting missing and extra characters in the data stream. The processor can therefore tolerate incorrect, missing or extra characters in the text stream, and can handle multiple levels of nesting and arbitrary boolean expressions within the search pattern. Another novel aspect of the processor is its ability to locate an enumerated subset of search terms or patterns within fixed or sliding windows.