Embedded DSP Processor Design, : Application Specific Instruction Set Processors

775 Pages·2008·17.69 MB·English

by  Dake Liu

Preface
In the late 1990s, when I was preparing a course called “Design of Embedded
DSP(DigitalSignalProcessing)Processors”atLinköpingUniversity,Sweden,Icould
notfindatextbookdescribingthefundamentalsofembeddedprocessordesign.It
becamemyfirstandprimemotivationforwritingthisbook.Duringmyworktime
inindustry,Icouldnotfindanysuitableandcomprehensivereferencebookeither,
whichledtomysecondmotivationforwritingsuchabook.Ithasbeenmybelief
thatthisbookwillbeavaluabletextbookorreferencebookforanyoneinterestedin
thedesignofembeddedsystemsinallitsaspects,fromhardwaredesigntofirmware
design.AlthoughthisbookwaswrittenmainlyforASIP(application-specificinstruc-
tionsetprocessor)orASIC(application-specificintegratedcircuit)designers,itwill
also benefit software programmers who want more hardware knowledge,such as
DSPapplicationengineers.
Whilereadingthisbook,youwillgetopportunitiestogothroughthedesignof
aprogrammabledeviceforaclassofapplications,stepbystep.Thematerialinthis
bookissuitableforteachingseniorundergraduatestudentsandgraduatestudents
inElectricalEngineeringandComputerEngineering.Thisbookcanalsobeusedas
a reference book for engineers who are designing or want to design application-
specific DSP processors,general processors,accelerators,peripheral modules,and
evenmicrocontrollers.Embeddedsystemdesigners(e.g.,DSPfirmwaredesigners)
will also benefit from the knowledge of real-time system design elaborated in this
book. Classical CPU designers will benefit from the exposed difference between
CPUandASIP.Thisbookisalsoafundamentalreferencebookforresearchers.
FundamentalDSPtheoryandbasicdigitallogicdesignareaddressedinthisbook
as background knowledge.Very basic concepts and methods were used without
redundantintroduction.Readerswithoutthefundamentalknowledgeshouldread
relevant books about DSP theory,logic design,and computer architecture before
readingthisbook.
DSP, asopposedtogeneral-purposecomputingsystems,hasbeenamajortech-
nologydrivenbyembeddedapplicationsandthesemiconductortechnologies.This
isevidentfromthegrowingmarketofDSP-basedproducts.Theincreasingneedfor
DSPandDSPprocessorscanbefoundeverywhereintoday’ssocietyinareassuch
asmultimedia,wirelesscommunications,Internetterminals,carelectronics,robot,
healthcare,environment monitoring and control,education,scientific computing,
industrialcontrol,transportation,anddefense.
DSP is used widely for various applications such as data enhancement, data
compression, pattern recognition, simulation, emulation, and optimization. Sig-
nal recovery in advanced digital communications is a good example of data
enhancement.Otherdataenhancementapplicationsincludeerrorcorrection,echo
cancellation,and noise suppression. Data compression is another important area
intoday’sdailyusedfacilities:forexample,voice,music,image,video,andInternet
data needs to be compressed to fit into a limited bandwidth for transmission and xix
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xx Preface
storage. If voice was not compressed by a DSP processor in a mobile phone,the
cost of a mobile phone call would be 10 to 15 times higher. If video signals
were not compressed,DVD players and digital video broadcasting would not be
possible.
Patternrecognitiontechniquesareusedforvoicerecognition,languagerecogni-
tion,andimagetargetrecognitionforhealthcare,cardriving,anddefense.Physical
simulation has been used for gaming,training (education),scientific computing,
defense,and experiments that are expensive or even impossible to realize in the
realworld.
The global market share of DSP processors and microcontrollers is more than
95%ofthetotalvolumeofprocessorssoldin2006.DSPprocessorsforembedded
applications have led to a major shift in the semiconductor industry.The sales of
DSPprocessorshavereached20%oftheglobalsemiconductormarketsince2002.
TakingonlytheDSPprocessorsinmobilephonesasanexample,thetotalsalesin
2006wasmorethan$10billionUS.
General-purposeDSPprocessors(commercialoff-the-shelfDSPprocessors)usu-
ally have a high degree of flexibility,a friendly design environment,and sufficient
design references. General-purpose DSP processors are preferred when require-
ments on power,performance,and silicon area are not very critical.When these
requirementsarestrict,embeddedDSPprocessorsasASIPwillbecomeanecessity.
Figure P.1 shows the trend of the different DSP market shares.The figure clearly
showsthatthefutureofASIPDSPisobviouslyexciting—thisismythirdmotivation
forwritingthisbook.
Most DSP applications can be categorized as streaming signal processing,in
which the processing speed is higher than the speed of incoming signals. Classic
DSP hardware for streaming signal processing was usually implemented on non-
programmableASICs to minimize the silicon cost. Recently programmability has
become a vital issue because the complexity as well as design costs keep going
higher. Programmability has been required by industries in order to support mul-
timodesormultistandardapplications.Thankstotheongoingprogressofmodern
FIGUREP.1
TrendofdifferentDSPmarketshares(FreehandDSP,Sweden).
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Preface xxi
VLSI(verylargescaleintegratedcircuits)technologies,programmablefeatureshave
beenrealisticsincethe1990s.
AnongoingtrendisthatthearchitectureofMPU(microprocessorsasthecentral
processorinpersonalcomputers)isconverging.ThearchitectureofDSPprocessors
isdiverging.OnereasonisthatapplicationsrunningonDSPsarediverging.However,
thefunctionalitieswillberelativelyfixedwhenaDSPprocessorisembeddedina
system.Anotherreasonisthattherequirementsareverycriticalonsiliconefficiency,
powerconsumption,anddesigncostofembeddedprocessorsorASIP.
General-purposeprocessordesignersthinkofultimateperformanceandultimate
flexibility.Theinstructionsetmustbegeneralbecausetheapplicationisunknown,
and the programmer’s behavior is unknown.ASIP designers have to think about
the application and cost first. Usually the biggest challenge forASIP designers is
the efficiency issue. Based on the carefully specified function coverage,the goal
ofanASIPdesignistoreachthehighestperformanceoversiliconandthehighest
performanceoverpowerconsumptionaswellasthehighestperformanceoverthe
designcost.Therequirementonflexibilityshouldbesufficientinsteadofultimate.
Theperformanceisapplication-specificinsteadofthehighest.Thisbookwillexpose
andanalyzethedifferencesbetweengeneral-purposeprocessordesignersandASIP
designers.
AnASIPisoftenaSIP(SiliconIntellectualPropertyorSiliconIP,orIP).MoreSoC
(system on a chip) solutions useASIP IP.Therefore,the focus of this book will be
thedesignofIPcoresofASIPforembeddedsystemsonachip.SiliconIPhasbeen
usedascomponentsinsiliconchipdesignssincethemid-1990s.Therequirements
for quality design of silicon IP became higher after 2000 because silicon IP has
beenwellacceptedandwidelyused.InFigureP.2,thesystemdesigncomplexityis
dividedintothesystemdesigncomplexityandthecomponentdesigncomplexity.
Around the middle to late 1980s,RTL components (for example,multipliers and
adders) were optimized as the lowest level components of system designs. RTL
componentstookacertaindegreeofdesigncomplexityfromthesystemdesignso
thatthesystemcouldberelativelymoreadvancedcomparingthesystemdesigned
onatransistorlevel.Duringthemid-1990s,thesystemdesignbecamesoadvanced
andcomplicatedthatprogrammableIPhastobeusedasthelowestlevelcomponent
torelaxthesystemdesigncomplexity.
BecauseanIPusuallyisdesignedbythethirdpartyoranotherdesignteam,the
systemcomplexitycanthereforebeshared.Also,becauseanIPusuallyisdesigned
for multiusers,the design cost usually is shared by multiusers;relatively high IP
design cost is therefore acceptable.This is the fourth motivation of writing the
book—to show ways to design high quality programmable IP as components for
multiusers.
The fourth motivation became even more important when the platform-based
designconceptwasintroducedrecently.Aplatformisapartlydesignedapplication-
specificsystemthatcanbeusedtoadapttoacustomdesignwithminimumcost.
The platform-based system design requires the minimum design cost while plug-
ging a programmable IP on the platform and running firmware on it. It means
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xxii Preface
FIGUREP.2
HandlingcomplexityofthedesignusingASIPIPandplatform.
that the design ofASIP must be both silicon-efficient and platform-oriented.The
platform-adaptiveASIP design skills offered by this book will thus be even more
interesting.
I deeply acknowledge the research and teaching contributions from my PhD
students in my Division of Computer Engineering,Department of Electrical Engi-
neering at Linköping University, Sweden. The labs of the course and part of
the contents of this book are based on their research work. Di Wu and Johan
Eilert read through the book and provided enormous suggestions. Per Karlström
managedallMSWordproblemsandfigureformattingusinghisfantasticWord-VBA
programming skills.Andreas Ehliar went through all code examples in the book.
Per Karlström, Johan Eilert,Andreas Ehliar, Di Wu, and Master students Vinodh
Ravinath and Bobo Svangård implemented the Senior DSP processor core.
Research engineer Anders (S) Nilsson made the assembler and instruction set
simulatorofSenior,theprocessorusedastheexampleofthebook.Acknowledg-
ment also goes to other PhD students:RizwanAsghar,Dr.Anders Nilsson,Dr. Eric
Tell,Dr.Tomas Henriksson,Dr. DanielWiklund,Dr. Ulf Nordqvist,and Lic. Mikael
Olausson. I thank all Master students who participated in the course“Design of
Embedded DSP Processors”from 1999 to 2007.
My sincere thanks go to Freehand DSPAB (Ltd.),Sweden (orVIATech Sweden
after2002),aleadingcompanydevelopingDSPprocessorsforcommunicationsand
home electronic applications. Special thanks to my friend and boss,CEO Harald
Bergh, who went through several chapters and provided very professional and
valuable suggestions. I was the cofounder,CTO,and vice president of Freehand
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Preface xxiii
DSPAB(Ltd.)Stockholm,Sweden,during1999and2002,whichwaslateracquired
byVIATechnologiesin2002.
IthankCoresonicAB(Ltd.),Linköping,Sweden,aleadingDSPcoreSIPcompany
forprogrammableradiobasebandsolutions.IamacofounderandcurrentlytheCTO
ofthiscompany.Isincerelythankmybestfriend,ProfessorChristerSvensson,atthe
DepartmentofElectricalEngineering(ISY),LinköpingUniversity,Sweden,whohad
beenmysupervisor(1990–1994)duringmyresearchtowardmytechnologydoctor
degree. Christer is the cofounder and the Chairman of the Board of Coresonic.
I also thank cofounders Dr. EricTell,Dr.Anders Nilsson,and Daniel Svensson for
many useful discussions and encouragements.All staff of CoresonicAB are greatly
acknowledged.
I greatly acknowledge the following experts for their insightful discussions:
VodafonechairProfessorGerhardFettweis,TUDresden;ProfessorChristophKessler
ofLinköpingUniversity;ProfessorLarsSvenssonofChalmersUniversity;Professor
Viktor Öwall of Lund University; Professor Petru Eles of Linköping University;
Dr.Carl-FredrikLendersonofSonyEricsson;ProfessorDr.XiaoningNieofInfineon
Munich;Dr.FranzDielacher,CSO,InfineonconnectionsVillach;andInfineonfellow
ProfessorDr.LajosGazsi,Düsseldorf.
Finally,the most acknowledgment and gratitude goes to my dear wife Meiying
and my daughterAngie.Without their love,understanding,and support,this book
wouldneverhavebeenpossible.
DakeLiu
December2007
Linköping,Sweden
REFERENCES
[1] Strauss,W. (2000). Digital signal processing,the new semiconductor industry technology
driver.IEEESignalProcessingMagazine,March,52–56.
[2] http://www.fwdconcepts.com.
[3] BDTI,DSPselectionguidehttp://www.bdti.com.
[4] Claasen,T.(2006).Anindustryperspectiveoncurrentandfuturestate-of-the-artinsystem-on-
chip(SoC)technology.ProceedingsoftheIEEE94(6).
[5] http://www.da.isy.liu.se/∼dake.
[6] http://www.viatech.se.
[7] http://www.coresonic.com.
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List of Trademarks and Product Names
ADIprocessors
ARMprocessors
CEVADSPprocessors
CoresonicLeoCoreprocessors
FreehandDSP
Freescale
InfineonCamelprocessor
IntelPentiumand8x86processors
NXPEVP16basebandprocessor
xxv
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xxvi List of Trademarks and Product Names
OpenriscofOpencores
SPICELL(SonyPanasonicIBM)processors
TI(TexasInstrument)DSPprocessors
XilinxFPGA
Tools and programs include MATLAB and
SimulinkofMathworks
DesigncompilerofSynopsys
LISAandProcessorDesignerofCoWare
ZSPofLSI
GCCfromGNU
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CHAPTER
1
Introduction
DSP theory, DSP applications, and implementation of DSP subsystem hardware
and algorithms will be reviewed in this chapter. Some real-time DSP applications
will be covered briefly in order to provide an introduction to implementation
costs (execution time and hardware complexity).Also,DSP architecture,embed-
ded systems, and other essential background knowledge will be collected and
reviewed.
Thisbookisintendedforreaderswhoalreadyhavesomefundamentalknowledge
in logic design,computer architecture,programming using C and HDL languages,
DSPtheory,anddigitalVLSIdesign.Applicationknowledgeindigitalcommunication
ordatacompressionisuseful,butnotnecessary.
Tomakereadingeasier,areadingguidefollows.
1.1 HOW TO READ THE BOOK
This book is organized into four parts.The first four chapters constitute Part 1,
whichprovidessomefundamentalknowledge.ThechaptersofPart1areorganized
asfollows:
1. Knowledge review, including DSP fundamentals, processor architectures,
real-timesystems,anddesignofembeddedsystems.
2. Numerical representation and precision control of fixed-point number
systemsinfixed-pointprocessors.
3. Review of ASIP and DSP architectures for different requirements and
applications.
4. IntroductiontodesignmethodologiesforASIPandDSPfirmware.
The second part of this book covers DSP assembly instruction set design and
designmethodologies.ThechaptersofPart2coverthefollowingtopics:
5. Identification of drawbacks and problems of Junior,a DSP processor with
anintuitiveassemblyinstructionsetfollowingClanguageprimitives. 1
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2 CHAPTER 1 Introduction
6. ProfilingforASIPinstructionsetdesignwithfocusonthedifferencebetween
profilingforqualitysoftwaredesignandprofilingforASIPdesign.
7. Instruction set design technique is discussed in detail based on identified
drawbacks of Junior and profiling knowledge. Instruction set design
includes trade-off decisions,design of RISC subset,CISC subset,addressing,
coding,anddesignforHWacceleration.
8. Introduction to the toolchain for assembly programming including code
analyzer,Ccompiler,assembler,linker,simulator,anddebugger.
9. Benchmarking of assembly instruction set based on DSP kernel algorithms
andapplications.
ThethirdpartofthisbookcoversDSPmicroarchitecturedesignandthedesign
ofDSPcoreindetail.Part3discussesthefollowingtopics:
10. MicroarchitecturedesigningeneralandASIPmicroarchitecturedesign.
11. RF(RegisterFile)designandimplementation.
12. ALU(ArithmeticandLogicUnit)designandimplementation.
13. MAC(MultiplicationandAccumulation)unitdesignandimplementation.
14. Controlpathdesignandimplementation.
15. Designandimplementationofmemorysubsystemsandaddressgenerators.
Part4coversadvancedissuesofapplication-specificDSPdesign:
16. Design and implementation of DSP peripherals including core periph-
eral modules (Interrupt Handler,Timer,and DMA module),interprocessor
buses,andchipperipherals(I/Oports).
17. DesignforfunctionalaccelerationandDSPaccelerators.
18. FirmwaredesignforbothDSPprocessorsandASIP.
19. IntegrationandverificationofASIP.
20. Design of parallelASIP for streaming signal processing.This chapter is not
writtenforundergraduatestudents.
Theappendixcontainstheseniorinstructionsetmanual,itsbenchmarking,and
RTLimplementation.
This book is written for both university students and engineers.The targeted
readersarecategorizedinTable1.1.
For university teachers and research supervisors,this book can be organized
for either a half-year course or a quarter-year course usingTable 1.2 and related
material available from the web page [1]. We suggest that teachers apply and
modify the lab work according to their own curriculum plans.
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