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ID:24596015
大小:31.26 KB
页数:17页
时间:2018-11-15
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1、附录4英文资料及译文1英文资料(FromDIGITALDESIGNprinciples&practices,JohnF.Wakerly)LanguageOverviewWhatisVHDL?VHDLisaprogramminglanguagethathasbeendesignedandoptimizedfordescribingthebehaviorofdigitalsystems.VHDLhasmanyfeaturesappropriatefordescribingthebehaviorofelectroniccom
2、ponentsrangingfromsimplelogicgatestocompletemicroprocessorsandcustomchips.FeaturesofVHDLallowelectricalaspectsofcircuitbehavior(suchasriseandfalltimesofsignals,delaysthroughgates,andfunctionaloperation)tobepreciselydescribed.TheresultingVHDLsimulationmodelscanth
3、enbeusedasbuildingblocksinlargercircuits(usingschematics,blockdiagramsorsystem-levelVHDLdescriptions)forthepurposeofsimulation. VHDLisalsoageneral-purposeprogramminglanguage:justashigh-levelprogramminglanguagesallowcomplexdesignconceptstobeexpressedascomputerpro
4、grams,VHDLallowsthebehaviorofcomplexelectroniccircuitstobecapturedintoadesignsystemforautomaticcircuitsynthesisorforsystemsimulation.LikePascal,CandC++,VHDLincludesfeaturesusefulforstructureddesigntechniques,andoffersarichsetofcontrolanddatarepresentationfeature
5、s.Unliketheseotherprogramminglanguages,VHDLprovidesfeaturesallowingconcurrenteventstobedescribed.ThisisimportantbecausethehardwaredescribedusingVHDLisinherentlyconcurrentinitsoperation.OneofthemostimportantapplicationsofVHDListocapturetheperformancespecification
6、foracircuit,intheformofwhatiscommonlyreferredtoasatestbench.TestbenchesareVHDLdescriptionsofcircuitstimuliandcorrespondingexpectedoutputsthatverifythebehaviorofacircuitovertime.TestbenchesshouldbeanintegralpartofanyVHDLprojectandshouldbecreatedintandemwithotherd
7、escriptionsofthecircuit. AstandardlanguageOneofthemostcompellingreasonsforyoutobecomeexperiencedwithandknowledgeableinVHDLisitsadoptionasastandardintheelectronicdesigncommunity.UsingastandardlanguagesuchasVHDLvirtuallyguaranteesthatyouwillnothavetothrowawayandre
8、capturedesignconceptssimplybecausethedesignentrymethodyouhavechosenisnotsupportedinanewergenerationofdesigntools.Usingastandardlanguagealsomeansthatyouaremorelikelyto
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