We describe race-free properties of a hardware description language called GEZEL. The language describes networks of cycle-true finite-state-machines with datapaths (FSMDs). We derive a set of four rules under which a network of such FSMDs satisfies the Kahn principle. When applying those rules, GEZEL programs will be determinate and a designer will thus obtain race-free hardware. We define extended FSMD networks as FSMD networks for which some components are user-defined and not specified as FSMDs. An important result is that the determinate properties of the FSMD network are also valid for the extended FSMD network provided that the user-defined components are determinate. Most hardware description languages do not have this determinacy. Their simulation semantics are dependent on simulator implementation, and on a run-time race resolution mechanism. We therefore position GEZEL as a model of computation that RTL designers should have in mind while creating RTL models. In fact, we ca...
Patrick Schaumont, Sandeep K. Shukla, Ingrid Verba