Modular Verification of SRT Division

  • Authors:
  • Harald Ruess;Natarajan Shankar;Mandayam K. Srivas

  • Affiliations:
  • Universität Ulm, Fakultät für Informatik, 89069 Ulm, Germany. ruess@informatik.uni-ulm.de;SRI International Computer Science Laboratory, Menlo Park, CA 94025, USA. shankar@csl.sri.com;SRI International Computer Science Laboratory, Menlo Park, CA 94025, USA. srivas@csl.sri.com

  • Venue:
  • Formal Methods in System Design
  • Year:
  • 1999

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Abstract

We describe a formal specification and mechanizedverification in PVS of the general theory of SRT division alongwith a specific hardware realization of the algorithm. Thespecification demonstrates how attributes of the PVS language(in particular, predicate subtypes) allow the general theory to bedeveloped in a readable manner that is similar to textbookpresentations, while the PVS {\tt table} construct allowsdirect specification of the implementation‘s quotient lookup table.Verification of the derivations in the SRT theory and for the datapath and lookup table of the implementation are highly automated andperformed for arbitrary, but finite precision; in addition, thetheory is verified for general radix, while the implementation isspecialized to radix 4. The effectiveness of the automation stemsfrom the tight integration in PVS of rewriting with decisionprocedures for equality, linear arithmetic over integers andrationals, and propositional logic. This example demonstrates thatthe resources of an expressive specification language and of ageneral-purpose theorem prover are not inimical to highly automatedverification in this domain, and can contribute to clarity,generality, and reuse.