Timing distribution in VHDL behavioral models

This paper describes a new CAD tool, TIMESPEC, developed for solving the timing distribution problem of allocating realistic delays to the internal primitives (RTL models) of a digital device by using the linear programming approach. The inconsistencies in the manufacturer’s specifications are also detected and corrected. TIMESPEC enables the use of imbedded timing in behavioral VHDL models and thus the end-to-end delays for all the paths in the digital device are made available. An interface is provided with an X-windows based graphical tool, the Modeler’s Assistant which allows enumeration of all the input-to-output paths in the device. Thus a CAD tool is made available to system or chip designers/modelers for building accurate and synthesizable VHDL models.