A Tour of Computer SystemsPPT演示课件

1,ATourofComputerSystems(2),C,2,Outline,LayersofcomputersystemsSuggestedreading4asidesinchapter1,CompilersAutumn2002,3,LayersofComputerSystems,CompilersAutumn2002,4,Utilities,ProgramminglanguageANSICCompilerGNU-gccToolsGNUtoolchain,eclipse(CDT),CompilersAutumn2002,5,GNU,FreesoftwareRichardStallman,1984AcompleteUnix-likesystemwithsourcecodeAnenvironmentAllmajorcomponentsofaUnixoperatingsystemExceptforkernel,CompilersAutumn2002,6,Platforms,HardwareplatformIntelIA-32OperatingsystemLinuxProgramminglanguageANSICUtilityGNU,eclipse(CDT)C,CompilersAutumn2002,7,RepresentationandManipulationInformation(1),C,8,Outline,BitandByteUnderstandmachinerepresentationsofnumbersSuggestedreading2.1.1,CompilersAutumn2002,9,WhyBit?,ModerncomputersstoreandprocessInformationrepresentedastwo-valuedsignalsTheselowlybinarydigitsarebitsBitsformthebasisofthedigitalrevolution,CompilersAutumn2002,10,TheDecimalRepresentation,Base-10Hasbeeninuseforover1000yearsDevelopedinIndiaImprovedbyArabmathematiciansinthe12thcenturyBroughttotheWestinthe13thcenturybytheItalianmathematicianLeonardoPisano,betterknownasFibonacci.,CompilersAutumn2002,11,WhyBit?,Usingdecimalnotationisnaturalforten-fingeredhumansButbinaryvaluesworkbetterwhenbuildingmachinesthatstoreandprocessinformation,CompilersAutumn2002,12,WhyBit?,Two-valuedsignalscanreadilyberepresented,stored,andtransmitted,ExamplesThepresenceorabsenceofaholeinapunchedcardAhighorlowvoltageonawireAmagneticdomainorientedclockwiseorcounterclockwise.,CompilersAutumn2002,13,WhyBit?,Theelectroniccircuitryisverysimpleandreliableforstoringandperformingcomputationsontwo-valuedsignalsThisenablingmanufacturerstointegratemillionsofsuchcircuitsonasinglesiliconchip,CompilersAutumn2002,14,GroupBits,Inisolation,asinglebitisnotveryusefulInEnglish,thereare26(or52)charactersinitsalphabet.TheyarenotusefuleitherinisolationHowever,thereareplentyofwordsinitsvocabulary.Howisthisachieved?Similarly,weareabletorepresenttheelementsofanyfinitesetbyusingbits(insteadofbit),CompilersAutumn2002,15,GroupBits,Todothis,wefirstgroupbitstogetherthenapplysomeinterpretationtothedifferentpossiblebitpatternsthatgivesmeaningtoeachpatterns8-bitchunksareorganizedasabyteDr.WernerBuchholzinJuly1956duringtheearlydesignphasefortheIBMStretchcomputer,CompilersAutumn2002,16,ValueofBits,Bits01010Value0*24+1*23+0*22+1*21+0*20=10Value102(1100110)Bits102=51*2+0(0)51=25*2+1(1)25=12*2+1(1)12=6*2+0(0)6=3*2+0(0)3=1*2+1(1)1=0*2+1(1),CompilersAutumn2002,17,GroupbitsasnumbersThreeencodings,UnsignedencodingRepresentingnumbersgreaterthanorequalto0UsingtraditionalbinaryrepresentationTwos-complementencodingMostcommonwaytorepresenteitherpositiveornegativenumbersFloatingpointencodingBase-twoversionofscientificnotationforrepresentingrealnumbers,CompilersAutumn2002,18,GroupbitsasnumbersUnderstandingnumbers,MachinerepresentationofnumbersarenotsameasIntegersandrealnumbersTheyarefiniteapproximationstointegersandrealnumbersSometimes,theycanbehaveinunexpectedway,CompilersAutumn2002,19,intisnotinteger,Overflow200*300*400*500=-884,901,888ProductofasetofpositivenumbersyieldedanegativeresultCommutativity,Fileinclusion,StandardLibrary,Headerfile,CompilersAutumn2002,29,FileInclusionandMacroSubstitution,MacroSubstitution,intj;main()return100+j;,CompilersAutumn2002,30,FileInclusionandMacroSubstitution,#include“filename”#include#defineforeverfor(;)/*infiniteloop*/#definesquare(x)(x)*(x),CompilersAutumn2002,31,FormattedOutput-Printf,intprintf(char*format,arg1,arg2,)printf(“%d,%dn”,i,j);%d,%idecimalnumber%ooctalnumber(withoutaleadingzero)%x,%Xhexadecimalnumber%csinglecharater,CompilersAutumn2002,32,IntegraldatatypeinC,ThereareseveraldatatypetorepresentintegersinCThedifferenceisthesizeoftheintegerItreflectstheimplementationofhardware,CompilersAutumn2002,33,TheContextofaCompiler(gcc),Sourceprogram(text),hello.c,CompilersAutumn2002,34,TheHelloProgram,SourceprogramCreatedbyeditorandsavedasatextfileBeginslifeasahigh-levelCprogramCanbereadandunderstandbyhumanbeingsTheindividualCstatementsmustbetranslatedbycompilerdriversSothatthehelloprogramcanrunonacomputersystem,CompilersAutumn2002,35,TheHelloProgram,TheCprogramsaretranslatedintoAsequenceoflow-levelmachine-languageinstructionsTheseinstructionsarethenpackagedinaformcalledanobjectprogramObjectprogramarestoredasabinarydiskfileAlsoreferredtoasexecutableobjectfiles,CompilersAutumn2002,36,Preprocessor,MacroSubstitution,Obtainwithcommandgcc-Ea.cSourcefilea.i,#1a.c#1#1#1a.c#1b.h1intj;#2a.c2main()return100+j;,CompilersAutumn2002,37,SourceCodeandAssemblyCode,Globalvariable,CompilersAutumn2002,38,MachineCode,CompilersAutumn2002,COMPILING,P,39,SourceCodes*.c,*.h,CProgramPreprocessor,SourceCodes*.i,CProgramCompiler,AssemblyCodes*.s,Assembler,Linker/Loader,GNUCompilerCollection,E,c,o,S,BinaryCodes*.out,BinaryCodes*.o,40,TheCProgrammingLanguage,Cwasdevelopedin1969to1973byDennisRitchieofBellLaboratories.TheAmericanNationalStandardsInstitute(ANSI)ratifiedtheANSICstandardin1989.ThestandarddefinestheClanguageandasetoflibraryfunctionsknownastheCstandardlibrary.,CompilersAutumn2002,41,TheCProgrammingLanguage,KernighanandRitchiedescribeANSICintheirclassicbookwhichisknownaffectionatelyas“K&R”.InRitchieswords,Cisquirky,flawed,andanenormoussuccess.Whythesuccess?,CompilersAutumn2002,42,TheCProgrammingLanguage,CwascloselytiedwiththeUnixoperatingsystemCwasdevelopedfromthebeginningasthesystemprogramminglanguageforUnix.MostoftheUnixkernel,andallofitssupportingtoolsandlibraries,werewritteninC.,CompilersAutumn2002,43,TheCProgrammingLanguage,CwascloselytiedwiththeUnixoperatingsystemAsUnixbecamepopularinuniversitiesinthelate1970sandearly1980s,manypeoplewereexposedtoCandfoundthattheylikedit.SinceUnixwaswrittenalmostentirelyinC,itcouldbeeasilyportedtonewmachines,whichcreatedanevenwideraudienceforbothCandUnix.,CompilersAutumn2002,44,TheCProgrammingLanguage,Cisasmall,simplelanguage.Thedesignwascontrolledbyasingleperson,ratherthanacommittee,andtheresultwasaclean,consistentdesignwithlittlebaggage.TheK&Rbookdescribesthecompletelanguageandstandardlibrary,withnumerousexamplesandexercises,inonly261pages.ThesimplicityofCmadeitrelativelyeasytolearnandtoporttodifferentcomputers.,CompilersAutumn2002,