Formal Analysis ofHardware Requirements

thatabout50percent ofproduct defects originate inflawed Formal languages areincreasingly usedtodescribe thefunc- requirements andthataround80percent ofrework effort tional requirements (specifications) ofcircuits. Thesere- canbetraced backtorequirement defects [17]. quirements areusedasameanstocommunicate design in- Inthis paper, weaddress thecrucial problem ofsupporttentandasbasis forverification. Inbothsettings itisof ingthedesigner inwriting highquality (functional) requireutmostimportance thatthespecifications areofhighqual- mentsofcircuits. (Inthefollowing weuserequirements and ity.However, formal requirements areseldom theobject specification assynonyms.) Wenotethatsuchrequirements ofvalidation, eventhough theycanbehardtounderstandanalysis isnottheactivity ofproducing animplementation andinteractions between themcanbesubtle. Inthis paper satisfying given properties. Rather, thefocus isonenhancwepresent techniques andguidelines toexplore andassure ingthequality oftherequirements before thedesign phase. thequality ofaformal specification. Wedefine atechnique We assumethattherequirements areexpressed inafortointeractively explore thesemantics ofaspecification by mallanguage suchasPSL.Theuseofaformal language simulating itsbehavior foruser-defined scenarios. Further- isafirst andsubstantial steptowards highquality specifimore, wedefine techniques toautomatically check specifica- cations, asitmakessubtle questions explicit thatotherwise tions against asetofuser-provided assertions, whichmust might behidden intheambiguity ofnatural language. Howbesatisfied, andasetofpossibilities, whichmustnotbecon- ever, aformal notation isobviously notenough toensure the tradicted. Theproposed techniques support theuserinthe quality ofthespecification. Inthis paperwedescribe techiterative development andrefinement ofhigh-quality speci- niques, methodological guidelines, andatool, RAT,forthe fications. formal analysis offunctional requirements. Ourapproach drawsfromtwocomplementary techniques: property simuCategories andSubjectDescriptors: lto n rpryasrne B-7.2 Hardware: DesignAids ~~~lation andproperty assurance. Property simulation allows thedesigner tointeractively General Terms:Design, Verification. explore thebehaviors associated withtherequirements: We