A model of VHDL for the analysis, transformation, and optimization of digital system designs

Besides a formal syntax definition, few formal semantic models for HDLs are ever constructed. This paper reports our efforts to construct formal models for the hardware description language VHDL. In particular, a static model for VHDL that addresses well-formedness, static equivalences, and static rewriting is presented. A rewriting algebra is presented that defines a set of transforms that allow the rewriting of VHDL descriptions into a reduced form. The dynamic semantics is under development and the reductions attained by the rewriting algebra have greatly simplified the language constructs that the dynamic semantics have to characterize.