STACCATO: disjoint support decompositions from BDDs through symbolic kernels

A disjoint support decomposition (DSD) is a representation of a Boolean function F obtained by composing two or more simpler component functions such that the component functions have no common inputs. The decomposition of a function is desirable for several reasons. First, it's a method to obtain a multiple-level implementation of a function. It leads to a partition in simpler blocks that easily results in smaller areas and fewer interconnects. Moreover, it exposes a parallelism in the computation of the function that can be exploited by hardware as well as during simulation. In this paper we present a novel algorithm, STACCATO, that generates a DSD decomposition starting from the BDD of a function. STACCATO is novel because: 1) it provides a complete description of each decomposition, that is, it computes the "kernel" function K relating the elements of each decomposition; and 2) it has better performance than previously known algorithms. Experimental results run on both IWLS and industrial test-benches show that STACCATO'S performance is in most cases three times as fast or more than previously known solutions.