Building Parallel, Embedded, and Real-Time Applications with Ada

388 Pages·2011·5.74 MB·English

by  John W. McCormick

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BUILDING PARALLEL, EMBEDDED, AND REAL-TIME
APPLICATIONS WITH ADA
Thearrivalandpopularityofmulti-coreprocessorshavesparkedarenewedinterest
in the development of parallel programs. Similarly, the availability of low-cost
microprocessorsandsensorshasgeneratedagreatinterestinembeddedreal-time
programs.Thisbookprovidesstudentsandprogrammerswhosebackgroundsarein
traditionalsequentialprogrammingwiththeopportunitytoexpandtheircapabilities
intoparallel,embedded,real-time,anddistributedcomputing.Italsoaddressesthe
theoretical foundation of real-time schedulinganalysis, focusing on theory that is
usefulforactualapplications.
Written by award-winning educators at a level suitable for undergraduates and
beginninggraduatestudents,thisbookisthefirsttrulyentry-leveltextbookinthe
subject.Completeexamplesallowreaderstounderstandthecontextinwhichanew
conceptisused,andenablethemtobuildandruntheexamples,makechanges,and
observetheresults.
john w. mccormick is Professor of Computer Science at the University of
NorthernIowa.
frank singhoff is Professor of Computer Science at Universite´ de
BretagneOccidentale(UniversityofBrest).
je´roˆme hugues is Associate Professor in the Department of Mathematics,
Computer Science, and Control at the Institute for Space and Aeronautics Engi-
neering(ISAE),Toulouse.

BUILDING PARALLEL, EMBEDDED,
AND REAL-TIME APPLICATIONS
WITH ADA
JOHN W. MCCORMICK
UniversityofNorthernIowa
FRANK SINGHOFF
Universite´deBretagneOccidentale
JE´ ROˆ ME HUGUES
InstituteforSpaceandAeronautics
Engineering(ISAE),Toulouse
cambridge university press
Cambridge,NewYork,Melbourne,Madrid,CapeTown,
Singapore,Sa˜oPaulo,Delhi,Tokyo,MexicoCity
CambridgeUniversityPress
TheEdinburghBuilding,CambridgeCB28RU,UK
PublishedintheUnitedStatesofAmericabyCambridgeUniversityPress,NewYork
www.cambridge.org
Informationonthistitle:www.cambridge.org/9780521197168
(cid:1)C J.W.McCormick,F.Singhoff,andJ.Hugues2011
Thispublicationisincopyright.Subjecttostatutoryexception
andtotheprovisionsofrelevantcollectivelicensingagreements,
noreproductionofanypartmaytakeplacewithoutthewritten
permissionofCambridgeUniversityPress.
Firstpublished2011
PrintedintheUnitedKingdomattheUniversityPress,Cambridge
AcatalogrecordforthispublicationisavailablefromtheBritishLibrary
LibraryofCongressCataloginginPublicationdata
McCormick,JohnW.,1948–
Buildingparallel,embedded,andreal-timeapplicationswithAda/JohnW.McCormick,
FrankSinghoff,JeromeHugues.
p. cm.
Includesbibliographicalreferencesandindex.
ISBN978-0-521-19716-8(hardback)
1.Ada(Computerprogramlanguage) 2.Parallelprogramming(Computerscience)
3.Embeddedcomputersystems–Programming. 4.Real-timedataprocessing.
5.Multiprocessors–Programming.
I.Singhoff,Frank. II.Hugues,Jerome. III.Title.
QA76.73.A35M375 2011
004(cid:2).35–dc22 2010053214
ISBN978-0-521-19716-8Hardback
CambridgeUniversityPresshasnoresponsibilityforthepersistenceor
accuracyofURLsforexternalorthird-partyinternetwebsitesreferredto
inthispublication,anddoesnotguaranteethatanycontentonsuch
websitesis,orwillremain,accurateorappropriate.
ThephotographonthecovershowsastronautStephenK.RobinsonstandingontheendoftheInternationalSpace
Station’sroboticmanipulatorsystem,Canadarm2.Thisarm,builtbyMacDonald,Dettwiler,andAssociatesLtd
fortheCanadianSpaceAgency,is17.6mlongwhenfullyextended.Ithassevenmotorizedjoints,eachacomplex
embeddedreal-timesystem.Givenitscrucialroleonthespacestation,thereliabilityofCanadarm2mustbe
impeccable.Thesoftwareforthesejointsandfortheworkstationthattheastronautsusetocontrolthemiswritten
inAda.Thisbookprovidesanintroductiontotheconceptsofconcurrentprogramming,embeddedsystems,and
real-timeconstraintsnecessaryforunderstandinganddevelopingthesoftwareforsuchsystems.
Contents
List of illustrations page viii
List of tables x
Foreword xi
Preface xiii
1 Introduction and overview 1
1.1 Parallel programming 2
1.2 Distributed programming 11
1.3 Real-time systems 12
Summary 19
Exercises 20
2 Sequential programming with Ada 23
2.1 Control structures 26
2.2 Subprograms 30
2.3 The Ada type model 35
2.4 Blocks and exceptions 62
2.5 Programming in the large 65
2.6 Object-oriented programming 76
2.7 Low-level programming 82
Summary 102
Exercises 103
3 Task basics 107
3.1 Defining tasks 107
3.2 The task life cycle 109
3.3 Task hierarchies 113
3.4 Exceptions 117
3.5 The implementation of Ada tasking 119
3.6 Other task features 119
vi Contents
Summary 121
Exercises 122
4 Communication and synchronization based on shared
objects 126
4.1 Mutual exclusion 126
4.2 The protected object 130
4.3 Synchronization 134
4.4 The protected entry 135
4.5 Restrictions 140
4.6 Entry queues 141
4.7 Some useful concurrent patterns 143
4.8 Requeue and private operations 149
4.9 Pragmas Atomic and Volatile 153
4.10 Interrupts 155
Summary 161
Exercises 162
5 Communication and synchronization based on direct
interaction 166
5.1 The rendezvous 166
5.2 The selective accept statement 171
5.3 Entry call options 180
5.4 State machines 181
Summary 191
Exercises 192
6 Distributed systems with Ada 195
6.1 What are distributed systems? 195
6.2 Middleware, architectures, and concepts 200
6.3 DSA, the Distributed Systems Annex 202
6.4 PolyORB: compilation chain and run-time for the DSA 212
6.5 Advanced DSA concepts 215
6.6 CORBA, the Common Object Request Broker
Architecture 221
6.7 Advanced CORBA concepts 236
6.8 CORBA versus the DSA 247
Summary 248
Exercises 250
7 Real-time systems and scheduling concepts 251
7.1 Task characteristics 253
7.2 Real-time schedulers 257
Contents vii
7.3 Dependent tasks 278
Summary 285
Exercises 286
8 Real-time programming with Ada 294
8.1 Expressing time 295
8.2 Implementing periodic tasks 298
8.3 Ada implementation of the car application 303
8.4 Handling shared resources 305
8.5 The Ada scheduling model 308
8.6 Ravenscar 312
8.7 POSIX 1003.1b and its Ada binding 314
8.8 POSIX implementation of the car application 324
8.9 Ada tasks versus POSIX processes 328
Summary 329
Exercises 330
9 Tools for building and verifying real-time
applications 333
9.1 Ada run-times to implement real-time applications 334
9.2 Some variants of the GNAT run-time 339
9.3 Validating scheduling of a system 347
Summary 355
Exercises 356
References 359
Index 365
Illustrations
1.1 An example of an embedded system 16
2.1 The Ada type hierarchy 37
2.2 Distribution of model numbers 41
2.3 Access variables 58
2.4 A linked list implementation of a stack of characters 60
2.5 Class diagram for commercial ovens 78
2.6 Association between register bits and enunciation lights 84
2.7 Memory mapped input/output 87
2.8 Port mapped input/output 89
2.9 Example digital to analog converter 90
3.1 The basic states of a task 110
3.2 The substates of executable 112
3.3 Parent tasks are suspended during the activation of a child
task 115
4.1 The read/write lock 133
4.2 The read lock 134
4.3 Entry queues for the protected bounded buffer 142
4.4 Tasks in the entry queues have precedence over those delayed
behind the lock 143
5.1 Statement sequencing in rendezvous 167
5.2 State machine diagram notation 182
5.3 State diagram for car headlights 183
5.4 State diagram for a large induction motor 188
6.1 Overview of a middleware 197
6.2 Distribution models 198
6.3 Interaction using a middleware 200
6.4 Ada user code and the Ada run-time 212
6.5 Sequence of actions for synchronous calls 216
6.6 Sequence of actions for asynchronous calls 216
6.7 Overview of CORBA 222