Method and apparatus for distinguishing combinational designs

A data processing system for determining whether a first and second designs are functionally different, comprising the following sub systems:

• a sub system configured to accomplish producing a first data structure from the first design, representative of a first set of minterms, wherein the first set of minterms defines a functionality of the first design;
• a sub system configured to accomplish producing a second data structure from the second design, representative of a second set of minterms, wherein the second set of minterms defines a functionality of the second design;
• a sub system configured to accomplish assigning a first weighted minterm count to the first data structure, which involves evaluating expressions in which weights are assigned the first set of minterms with 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 total weight to a minterm based at least on weights assigned to variables of the minterm, and wherein the design level weighting function assigns a total weight to a combinational sub-design;
• a sub system configured to accomplish assigning a second weighted minterm count to the second data structure, which involves evaluating expressions in which weights are assigned to the second set of minterms with the variable level weighting function, the minterm level weighting function and the design level weighting function;
• a sub system configured to accomplish deciding the first and second designs are functionally different in response to determining that the first weighted minterm count is not within a first tolerance of the second weighted minterm count.

A non-transitory computer readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for determining whether a first and second designs are functionally different, the method comprising:

• producing a first data structure from the first design, representative of a first set of minterms, wherein the first set of minterms defines a functionality of the first design;
• producing a second data structure from the second design, representative of a second set of minterms, wherein the second set of minterms defines a functionality of the second design;
• assigning a first weighted minterm count to the first data structure, which involves evaluating expressions in which weights are assigned to the first set of minterms with 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 total weight to a minterm based at least on weights assigned to variables of the minterm, and wherein the design level weighting function assigns a total weight to a combinational sub-design;
• assigning a second weighted minterm count to the second data structure, which involves evaluating expressions in which weights are assigned to the second set of minterms with the variable level weighting function, the minterm level weighting function and the design level weighting function;
• deciding the first and second designs are functionally different in response to determining that the first weighted minterm count is not within a first tolerance of the second weighted minterm count.