Extended abstract: a race-free hardware modeling language

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 can generate SystemC and other HDL code from GEZEL models, thereby guaranteeing the determinacy in the generated HDL code.