A new synthesis procedure for atomic rules containing multi-cycle function blocks

A new method for hardware synthesis from atomic rules where rules can take unknown number of cycles is presented. Some complex functions, especially the ones involving data-dependent control, are more easily expressed as loops and take much less area when implemented as multi-cycle folded circuits. Multicycle rules also provide a high-level method for the designer to deal with the timing-closure problem by treating a long combinational path as a multicycle path. Our synthesis procedure uses minimal extra storage and executes all rules eagerly. It resets all those rules whose read sets are affected by a committing rule. It also makes use of rule reservations to avoid a short rule from resetting a long rule repeatedly. This technique automatically takes advantage of different timings of different conditional branches. Our syntax-directed synthesis procedure composes signals indicating when a computation is done and when inputs to a computation have changed. Preliminary results from our implementation look very promising.