US 7,872,890 Bl Jan. 18, 2011
COUNTER CIRCUIT FOR REGULAR
EXPRESSION SEARCH ENGINES
Inventor: Alexey Starovoytov, Los Gatos, CA
Assignee: NetLogic Microsystems, Inc., Santa
Clara, CA (US)
Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 52 days.
Filed: Aug. 10, 2009
Related U.S. Application Data
Provisional application No. 61/087,581, filed on Aug. 8, 2008.
U.S. CI 365/49.17; 365/236; 365/49.1
Field of Classification Search 365/49.17,
365/236,49.1,189.07; 711/108 See application file for complete search history.
U.S. PATENT DOCUMENTS
A counter circuit is configured to simultaneously maintain individual character match count values for a plurality of overlapping substrings of an input string of characters that match a portion of a regular expression stored in a plurality of rows of content addressable memory (CAM) cells of a ternary CAM device. The counter circuit is selectable between a normal operational mode in which all matching portions of the input string are identified, and a minimum match length operational mode in which only matching portions of the input string that have at least a specified minimum number of characters are identified.
32 Claims, 16 Drawing Sheets