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Area-Oriented Comparison with 3D

Our second experiment (also shown in Table 1) shows the results of an area-oriented comparison of MINIMALIST and 3D.

The cost metric that best approximates area for technology-independent two-level logic is total literal count; hence, total literal count is used in this comparison.

Based on the above observation, we now indicate the settings of the various modes of MINIMALIST for this experiment. The vast majority of the MINIMALIST results in this set of runs use the fed-back output machine implementation style. Again, the table identifies the particular style chosen for each design. Throughout, MINIMALIST is directed to use the multi-output logic implementation style, and the literal count cost function, which best minimizes total literal count. Finally, the encoding step uses fixed-length constraint satisfaction mode.

These runs were obtained using a script identical to that of Figure 4, but using the multi-output logic implementation style. In particular, the single-output ('-s') flag was removed from the state encoding and logic minimization steps. Again, the cost function used was total literal count.

As shown in Table 1, MINIMALIST's term-sharing across outputs and next-state provides for significant reductions in total area. MINIMALIST's results for the area-targetted run show an average reduction of \( 33\% \) in total literal count over 3D, the best being \( 48\% \) for sc-control. For all designs, MINIMALIST achieved strictly better results than 3D. Although these runs did not target product count directly, they offer similarly dramatic reductions by that metric as well. An average of \( 42\% \) improvement is observed, the best being \( 57\% \) for sc-control. Again, MINIMALIST's results are strictly better than 3D in every case.

Unlike the performance-targetted runs, the code length used by MINIMALIST rarely exceeded that of 3D (only 3 times out of 23 designs), and never by more than 1 bit. In fact, MINIMALIST uses slightly fewer total state bits over the entire benchmark suite than does 3D, by roughly \( 5\% \).


next up previous
Next: Area-Oriented Comparison with UCLOCK Up: Results Previous: Performance-Oriented Comparison with 3D
Steven Nowick
1999-07-28