Patent ID: 8074194
Filing Date: 2011-12-06
Classification: G06F

Abstract:
1. A method for determining whether a first and a second design are functionally different, comprising: producing first, second and third data structures, representative of first, second and third sets of minterms, where the first set of minterms represents a functionality of a first design that always produces a first value for a don't care combination, the second set of minterms represents a functionality of the first design that always produces a second value for a don't care combination and the third set of minterms only produces a third value upon receiving an input representing a don't care combination of the first design; producing a fourth data structure, representative of a fourth set of minterms, wherein the fourth set of minterms represents a functionality of a second design; producing a fifth minterm count from the third and fourth data structures, wherein the fifth minterm count is equivalent to a count of a fifth set of minterms that represents a functionality of the second design that always produces the first value for a don't care combination; assigning first, second and fourth minterm counts to the first, second and fourth data structures; deciding, by a computer, the first and second designs are functionally different, unless the first minterm count is within a first tolerance of the fifth minterm count and the fourth minterm count is within a range defined by the first and second minterm counts; and wherein the first, second, fourth and fifth minterm counts are each determined by a variable-level weighting function, a minterm-level weighting function and a design-level weighting function, wherein the variable level weighting function assigns a weight to a variable of a minterm, wherein the minterm level weighting function assigns a weight to a minterm based at least on weights assigned to variables of the minterm, and wherein the design level weighting function assigns a weight to a combinational sub-design.