Patent ID: 7660140
Filing Date: 2010-02-09
Classification: G11C

Abstract:
1. A content addressable memory (CAM) device configured to store and implement search operations between an input string of characters and a regular expression of the form R 1 R 3 R 2 , wherein R 1 is a prefix string, R 3 is an intermediate expression having a quantified number m, wherein m is an integer, of characters belonging to a specified character class, and R 2 is a suffix string, the CAM device comprising: a first row of CAM cells configured to store the prefix string and to assert a prefix match signal if the input string matches the prefix string; a second row of CAM cells configured to store the suffix string; a third row of CAM cells configured to store the character class and to assert a character class match signal for each input character that matches the character class; and a sequencing logic circuit having an input to receive the character class match signal and having an output to generate a trigger signal indicating whether a sequence of m input characters matches the character class, wherein the trigger signal selectively enables the second row of CAM cells.