Table Of ContentSYSTEM DESIGN
A Practical Guide with SpecC
SYSTEM DESIGN
A Practical Guide with SpecC
Andreas Gerstlauer
Rainer Diimer
Junyu Peng
Daniel D. Gajski
Center for Embedded Computer Systems
University ofC alifornia, lrvine
SPRINGER SCIENCE+BUSINESS MEDIA, LLC
Library of Congress Cataloging-in-Publication Data
A C.I.P. Catalogue record for this book is available
from the Library of Congress.
ISBN 978-1-4613-5575-5 ISBN 978-1-4615-1481-7 (eBook)
DOI 10.1007/978-1-4615-1481-7
Copyright © 2001 Springer Science+Business Media New York
Originally published by Kluwer Academic Publishers in 2001
Softcover reprint of the hardcover 1s t edition 2001
AII rights reserved. No part of this publication may be reproduced, stored in a
retrieval system or transmitted in any form or by any means, mechanical, photo
copying, recording, or otherwise, without the prior written permission of the
publisher, Springer Science+Business Media, LLC
Printed on acid-free paper.
Table of Contents
Table of Contents v
Preface ix
Acknowledgement xiii
1. The SpecC Language 1
Outline 2
1.1 Introduction 3
1.2 Computational Models 5
1.2.1 Finite State Machine 6
1.2.2 Data Flow Graph 7
1.2.3 Finite State Machine with Datapath 8
1.2.4 Super-State Finite State Machine with Datapath 9
1.2.5 Hierarchical Concurrent Finite State Machine 10
1.2.6 Program State Machine 11
1.3 The SpecC Model 12
1.3.1 Traditional Model 12
1.3.2 SpecC Model 14
1.3.3 Protocol Inlining 15
1.3.4 Plug-and-Play with Computation 17
1.3.5 Plug-and-Play with Communication 22
1.4 System-level Language Requirements 26
1.4.1 Language Goals 26
1.4.2 Language Requirements 28
1.5 The SpecC Language 29
1.5.1 Foundation 29
1.5.2 Types 33
1.5.3 Structural Hierarchy 35
1.5.4 Behavioral Hierarchy 38
SYSTEM DESIGN: A PRACTICAL GUIDE WITH SPECC
1.5.5 Finite State Machine Execution 40
1.5.6 Pipeline Execution 41
1.5.7 Communication 45
1.5.8 Synchronization 48
1.5.9 Exception Handling 51
1.5.10 Timing 53
1.5.11 Library Support 57
1.5.12 Persistent Annotation 58
1.6 Summary and Conclusion 60
1.6.1 Summary 60
1.6.2 Conclusion 61
1.6.3 Further Information 62
2. Modeling and Design with SpecC 63
Outline 64
2.1 Introduction 65
2.1.1 Abstraction Levels 66
2.1.2 Design Flow 69
2.1.3 SpecC Methodology 71
2.2 Specification Model 72
2.2.1 Specification Model Example 73
2.2.2 Communication versus Computation 76
2.3 Architecture Refinement 80
2.3.1 Behavior Partitioning 82
2.3.2 Variable Partitioning 91
2.3.3 Execution Time 97
2.3.4 Scheduling 99
2.4 Architecture Model 104
2.5 Communication Synthesis 106
2.5.1 Channel Partitioning 108
2.5.2 Protocol Insertion 116
2.5.3 IP Components 138
2.5.4 Protocol Inlining 142
2.6 Communication Model 151
2.7 Backend 152
2.7.1 Hardware Synthesis 154
2.7.2 Software Synthesis 157
2.7.3 Interface Synthesis 160
2.7.4 Implementation Model Example 167
2.8 Implementation Model 171
2.9 Summary and Conclusions 172
3. Design of a GSM Vocoder 175
Outline 176
3.1 Introduction 177
3.1.1 GSM Vocoder Standard 178
3.2 Specification Model 179
3.2.1 Encoding Hierarchy 180
3.2.2 Profiling 181
Table of Contents
3.3 Architecture Exploration 182
3.3.1 Estimation 183
3.4 Architecture Model 185
3.5 Communication Synthesis 186
3.6 Communication Model 187
3.7 Backend 188
3.8 Implementation Model 190
3.9 Summary & Conclusions 191
4. Design of a JBIG Encoder 193
Outline 194
4.1 Introduction 195
4.1.1 JBIG Block Diagram 196
4.2 Specification 197
4.2.1 Specification Model 198
4.3 Partitioning 199
4.3.1 Solution 1 200
4.3.2 Solution 2 201
4.3.3 Solution 3 202
4.3.4 Solution 4 203
4.3.5 Results 204
4.3.6 Selection 206
4.4 Architecture Model 207
4.5 Communication model 208
4.5.1 Memory-Bus Interface 209
4.6 JBIG Hardware Design 213
4.6.1 JBIG Hardware Architecture 214
4.7 Conclusions 215
5. SpecC Design Environment 217
Outline 218
5.1 Introduction 219
5.1.1 System Validation 221
5.1.2 SpecC Scope 222
5.1.3 SpecC Methodology 223
5.2 Refinement 224
5.2.1 User Interface 225
5.2.2 Profiling and Estimation 226
5.2.3 Interactive Refinement 227
5.2.4 Automatic Refinement 228
5.2.5 Validation 229
5.3 SpecC Engine 230
5.3.1 Refinement Engine 231
5.3.2 Exploration Engine 232
5.3.3 Synthesis Engine 233
5.4 Conclusions 234
References 235
6. SpecC Technology Open Consortium 237
SYSTEM DESIGN: A PRACTICAL GUIDE WITH SPECC
6.1 Introduction 238
6.2 Motivation 238
6.2.1 Productivity Gap 239
6.2.2 SpecC Technology 240
6.3 The SpecC Technology Open Consortium 246
6.3.1 Purpose 247
6.3.2 History 248
6.3.3 Plans 249
6.3.4 Membership 250
Index 253
Preface
With the ever increasing complexity and time-to-market pressures in the design of
systems-on-chip (SOCs) or embedded systems in general, both industry and EDA
vendors are trying to move the design to higher levels of abstraction, in order to
increase productivity. At higher levels, there is no difference between hardware and
software. An SOC is the combination of hardware and software, and at the system
level the disciplines merge.
Great productivity gains can be achieved by starting design from an executable
system specification instead of an RTL description as the golden reference model,
throwing away all system models developed earlier in the process. However, we are
still just at the beginning of understanding the design process at the system level. No
tools and no well-defined design flows are available from industry or EDA vendors.
A paradigm shift is necessary in the community, moving from the simulation culture
to a synthesis culture. Traditionally, in a simulation-oriented design flow, models
may be written in a variety of ways as long as they simulate correctly. For a
synthesis-oriented design flow, however, their meaning needs to be defined uniquely.
In general, models written in simulation languages are not synthesizable.
In the traditional way, this problem was solved by sub setting the language used by
the models. In this case, the semantic variance is resolved by restricting the language
to certain interpretations. However, such language subsetting destroys the
interoperability among different groups, internal or external to a design house,
different EDA vendors, and so on.
Instead of adapting the models and the design flow to the capabilities offered by a
certain language, managing the complexity at higher levels of abstraction is not
possible without having a very well-defined system-level design flow. A well-defined
SYSTEM DESIGN: A PRACTICAL GUIDE WITH SPECC
design methodology is the basis for all, synthesis, verification, design automation,
and so on. Only then can we find or create a language that actually fits the desired
flow, and not vice versa.
The first step in defining a successful methodology is to define the different
abstraction levels through which a specification is brought down to an
implementation. Then, we can define the corresponding methodology, i.e. the models
of the design at each abstraction level and the transformations between the models.
Finally, a language needs to be developed, or adapted, that supports modeling at the
different levels, refinement from one model to the other, verification of models and
transformations, etc. The language should also capture the design flow clearly and
unambigiously for both, humans and CAD tools.
In this book, we present a system-level design methodology and language that are the
result of decades of research done in the area of SOC design. We define four
abstraction levels from specification down to RTL, guidelines for design modeling at
each level, rules for stepwise refinement between the models, and the well-defined,
smooth design flow and design environment at the system-level resulting from
putting together all of the above.
We elaborate the models and refinements in detail by moving a simple design
example through the whole design process. All the models presented in this book are
coded in the SpecC language. SpecC is a language that was developed exactly for the
purpose of supporting a system-level design flow, and it therefore satisfies all the
requirements of synthesizability, verifiability, and so on. SpecC is a superset of C and
adds a minimal, orthogonal set of concepts needed for system design. It is currently
in the process of being standardized. Open-source implementations of the language
are freely available.
This book is organized as follows: First, to introduce the methodology, we describe
the SpecC language as an example of a dedicated, synthesis-oriented system-level
design language (SLDL) in Chapter 1. Then, in Chapter 2, we discuss the four
different abstraction levels in system design, define the models at each level, and
describe in detail how to gradually refine one model into the next. In order to
demonstrate the methodology, we apply it to two industrial-strength examples, a
voice encoder/decoder for mobile telephony and a picture encoder, in Chapter 3 and
Chapter 4, respectively. In Chapter 5, we describe a complete design environment
and possible tools, which can be developed around the described methodology.
Finally, in Chapter 6, we introduce the SpecC Technology Open Consortium, which
was founded as an effort to propose and promote the SpecC language as a world
wide standard for interoperability, IP exchange, etc.
This book presents the system design flow following a simple example through the
whole process in an easy-to-follow, step-by-step fashion. Each step is described in
detail in pictorial form and with code examples in SpecC. For each picture slide, we
provide a detailed explanation of the concepts presented below. This format is suited
for tutorials, seminars, self-study, as a guided reference carried by examples, or as
teaching material for courses on system design.
Preface
This book will benefit designers and design managers of complex SOCs, or
embedded systems in general, by allowing them to develop new methodologies from
these results, in order to increase design productivity by orders of magnitude.
Designers at the RTL, logical or physical levels, who are interested in moving up to
the system-level, will find a comprehensive overview within. The design models in
the book define IP models and functions for IP exchange between IP providers and
their users. A well-defined methodology like the one presented in this book will help
product planning divisions to quickly develop new products or to derive completely
new business models, like e-design or product-on-demand. Finally, researchers and
students in the area of system design will find an example of a formal, well
structured design flow in this book.
Irvine, March 2001
A. Gerstlauer, R. Domer, J. Peng, D. Gajski.
