US Patent 7127693 Device for creating timing constraints

A datapath extraction unit extracts, from among datapaths on which a timing verification is to be performed, those datapaths from a netlist, timing constraints, and a cell library, that are established between at least two child blocks of a parent block. A datapath output unit prepares and presents to a user a datapath list in which timing exceptions can be specified. A timing constraint modification unit modifies the previous timing constraints according to the timing exceptions specified by the user and creates new timing constraints.