Method and apparatus for re-assigning priority in a partitioned content addressable memory device

A method of re-assigning priority between a plurality of content addressable memory (CAM) blocks in a CAM device, each CAM block including an array of CAM cells, the method comprising:

• storing, for each CAM block, a block index indicative of the CAM block's priority in the device;
• providing, for each CAM block, a row index of a row that stores data that matches comparand data;
• and
• combining each row index with a corresponding block index to generate a device index for each CAM block, wherein each block index is a dynamic value which may be modified to re-assign priority between the CAM blocks.

A method of re-assigning priority between a plurality of content addressable memory (CAM) blocks in a CAM device when one or more of the CAM devices are disabled, the method comprising:

• storing, for each CAM block, a block index indicative of the CAM block's priority in the device;
• disabling the one or more CAM blocks;
• and
• modifying the block index of at least one remaining enabled CAM blocks to re-assign the CAM block's priority in the device.

A content addressable memory (CAM) device, comprising:

• a plurality of CAM blocks, each comprising:
• an array of CAM cells organized in a plurality of rows and columns, each row having a match line to indicate a match condition for the row during a compare operation;
• a block priority encoder coupled to the plurality of match lines and having an output to provide a row index of a row that stores data that matches comparand data;
• and
• match flag logic coupled to the plurality of match lines to generate a block match flag signal;
• and
• a programmable main priority encoder coupled to receive the row indexes and the block match flag signals and to output one of the row indexes and one of a plurality of programmable block indexes as a device index for the CAM device.