Patent ID: 7987400

Claim:
A method for assigning scan chains to a STUMP in a hierarchical IC using program code embodied on a non-transitory computer readable medium, including the steps of: differentiating unlimited chains of a design for said hierarchical IC having certain types of chains that are of an unlimited type and which are differentiated from others that are of a limited type, and identifying unlimited chains so differentiated that need to be connected to an unlimited STUMP; defining with data of said design a start point and an end point of the unlimited STUMP to which the unlimited chains need to be connected; circumscribing a physical area occupied by the identified unlimited chains of said design and by the start point and the end point of the unlimited STUMP with a rectangular physical bounding box and dividing said box into a grid comprised of a plurality of smaller grid boxes of smaller areas; determining a grid box to grid box connectivity route to access the plurality of smaller grid boxes between the start point and the end point by means of a computer running a routing algorithm; determining a chain to chain connectivity route among the identified unlimited chains in each smaller grid box; determining a connectivity route routing a connection between an ending unlimited chain in one smaller grid box and a beginning unlimited chain in an associated smaller grid box to connect the start point and the end point of the unlimited STUMP; randomly assigning to a limited STUMP a limited chain that can be physically reached by the limited STUMP for connecting the limited chain to the limited STUMP; and adding an additional limited chain to the limited STUMP based on a number of latches in the additional limited chain and a number of latches already assigned to the limited STUMP such that a combined number of latches does not exceed a latch number limitation, and based on a physical location of the additional limited chain such that inclusion of the additional limited chain does not violate timing constraints.