Question: String matching with CAM?

Question

Has anyone used Content Addressable Memory to perform string matching?

I don't know much of anything about CAM, but I can imagine it would be much more flexible than hard-coding the strings I want to search for. However, will there be a huge hit in speed? I realize they can be read in 1 clk, but will the max speed of the FPGA take a hit?

I don't suppose there are coded examples out there?

Ray Andraka · Accepted Answer

All the CAM really is, is a soft version of the hard coded logic.  What Imean isby using the CAM you have the capability of reloading the 'tables' usedfor thehard coded decode.  In the case of the Xilinx CAM implementation, it isbasicallyan SRL-16 that gets reloaded when you write the CAM.  Reads are the sameas ifthe SRL16 was just a LUT.  If your character set reference is notchanging, then aLUT will serve the exact same function with possibly less overhead (theCAM needsa full decode on the match to handle all possibilities).Seth wrote:----Ray Andraka, P.E.President, the Andraka Consulting Group, Inc.401/884-7930     Fax 401/884-7950email  "They that give up essential liberty to obtain a little  temporary safety deserve neither liberty nor safety."                                          -Benjamin Franklin, 1759

Question: String matching with CAM?

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