Compact architecture for high-throughput regular expression matching on FPGA

In this paper we present a novel architecture for high-speed and high-capacity regular expression matching (REM) on FPGA. The proposed REM architecture, based on nondeterministic finite automaton (RE-NFA), efficiently constructs regular expression matching engines (REME) of arbitrary regular patterns and character classes in a uniform structure, utilizing both logic slices and block memory (BRAM) available on modern FPGA devices. The resulting circuits take advantage of synthesis and routing optimizations to achieve high operating speed and area efficiency. The uniform structure of our RE-NFA design can be stacked in a simple way to produce multi-character input circuits to scale up throughput further. An n-state m-character input REME takes only O (n X log₂ m) time to construct and occupies no more than O (n X m) logic units. The REMEs can be staged and pipelined in large numbers to achieve high parallelism without sacrificing clock frequency.

Using the proposed RE-NFA architecture, we are able to implement 3 copies of two-character input REMEs, each with 760 regular expressions, 18715 states and 371 character classes, onto a single Xilinx Virtex 4 LX-100-12 device. Each copy processes 2 characters per clock cycle at 300 MHz, resulting in a concurrent throughput of 14.4 Gbps for 760 REMEs. Compared with the automatic NFA-to-VHDL REME compilation [13], our approach achieves over 9x throughput efficiency (Gbps*state/LUT). Compared with state-of-the-art REMEs on FPGA, our approach also indicates up to 70% better throughput efficiency.