An efficient algorithm for performance-optimal FPGA technology mapping with retiming

It is known that most field programmable gate array (FPGA) mapping algorithms consider only combinational circuits. Pan and Liu [1996] recently proposed a novel algorithm, named SeqMapII, of technology mapping with retiming for clock period minimization. Their algorithm, however, requires O(K³n⁵log(Kn²)logn) run time and O(K²n²) space for sequential circuits with n gates. In practice, these requirements are too high for targeting K-lookup-table-based FPGA´s implementing medium or large designs. In this paper, we present three strategies to improve the performance of the SeqMapII algorithm significantly. Our algorithm works in O(K² nln|P_v|logn) run time and O(K|P_v|) space, where n_l is the number of labeling iterations and |P_v | is the size of the partial flow network. In practice, both n_l and |P_v| are less than n. Area minimization is also considered in our algorithm based on efficient low-cost K-cut computation