Counter circuit for regular expression search engines

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US007872890B1

United States Patent

Starovoytov

(io) Patent No.: (45) Date of Patent:

US 7,872,890 Bl Jan. 18, 2011

(56)

COUNTER CIRCUIT FOR REGULAR
EXPRESSION SEARCH ENGINES

Inventor: Alexey Starovoytov, Los Gatos, CA
(US)

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.

Appl.No.: 12/538,852

Filed: Aug. 10, 2009

Related U.S. Application Data

Provisional application No. 61/087,581, filed on Aug. 8, 2008.

Int. CI.

G11C15/00 (2006.01)

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.

References Cited

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