Method and apparatus for restricted search operation in content addressable memory (CAM) devices
OwnerDavid V. James, Jagadeesan Rajamanickam +1inventors
InventorsDavid V. James, Jagadeesan Rajamanickam, Michael C. Stephens, Jr.
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Abstract
According to an embodiment, a content addressable memory (CAM) device (104) may be capable of executing a “restricted” search operation. A restricted search operation (an “explore” or “search beyond” operation) may compare only a portion of the CAM entries to a search key device. Preferably, a restricted search operation may restrict searches to entries having an index value greater than a received search index value.
Claims13
In a content addressable memory (CAM) device having a plurality of CAM entries, a search method, comprising the steps of:
- searching at least one portion of the CAM entries according to a CAM entry identifier that distinguishes the at least one portion of the CAM entries from another different portion of the CAM entries, the CAM entry identifier corresponding to a CAM entry having a data value that matched a search key value in a previous search operation;
- generating match results for entries in the at least one portion that match an applied search key value;
- and
- searching a second portion of the CAM entries that has fewer entries than the at least one portion of the CAM entries, the second portion being determined according to a highest priority match result from the generated match results.
A content addressable memory (CAM) device, comprising:
- an entry disable circuit coupled to a plurality of CAM entries that selectively disables a portion of the CAM entries according to an entry identifier corresponding to one of the CAM entries, the entry disable circuit providing an enable signal to each CAM entry and further including a string decoder that deactivates enable signals for one portion of the CAM entries and activates the enable signals for a different portion of the CAM entries according to an activated address line;
- and
- a priority encoder that generates an index value for a highest priority enabled CAM entry having data that matches an applied search key.
Dependencies are inferred from the claim text.