Transcript Models.ppt

Essential Issues in Codesign:
Models
Part of
HW/SW Codesign of Embedded
Systems Course (CE 40-226)
Winter-Spring 2001
Codesign of Embedded Systems
1
Today programme

Essential issues in codesign
 Models
 Architectures
 Languages
Winter-Spring 2001
Codesign of Embedded Systems
2
Models

Model should be




Formal => avoid ambiguity
Complete => can describe entire system
Comprehensible and easy-to-modify
Model vs. Language


We use a model to decompose a system into
pieces (Model implies a way of thinking)
We generate a specification by describing these
pieces in a particular language (Language is a tool
for description)
Winter-Spring 2001
Codesign of Embedded Systems
3
Models:
Finite-State Machines (FSM)



A set of states and a set of transitions
between them
Most popular model for control systems
Formal definition


<S,I,O,f,h>
Depending on output function (h)

Mealy machine / Moore machine
Winter-Spring 2001
Codesign of Embedded Systems
4
Models:
Dataflow Graph (DFG)


Most popular model for computation-intensive
systems
Its basic principles



Asynchrony: all operations execute when and only
when all its operands are available
Functionality: operations are functions with no
side-effects => execution order is not important
Formal definition

<N,A,V,v0,f>
Winter-Spring 2001
Codesign of Embedded Systems
5
Models:
FSM with Datapath (FSMD)



Both control and computation are
required in most systems
FSMD is a combination of FSM and DFG
models
Formal definition



<S,I,O,f,h>
f = {fC,fD}
h= {hC,hD}
Winter-Spring 2001
Codesign of Embedded Systems
6
Models:
FSM with Datapath (cont’d)

Neither FSM nor FSMD are suitable for
complex systems

Concurrency


Explosion in states
Hierarchy

Explosion in arcs
Winter-Spring 2001
Codesign of Embedded Systems
7
Models:
Hierarchical Concurrent FSMs





Extension of FSM, supporting
concurrency and hierarchy
Like FSM: sets of states and transitions
Unlike FSM: each state can consist of
concurrent substates
Transitions can be structured or
unstructured
An example language: Statecharts
Winter-Spring 2001
Codesign of Embedded Systems
8
Models:
Programming Languages

Heterogeneous model


support data, and control modeling
Major PL types

Imperative (C, Pascal)


Control-driven model of execution
Declarative

Demand-driven / Pattern-driven model of
execution
Winter-Spring 2001
Codesign of Embedded Systems
9
Models:
Programming Lang. (cont’d)

Declarative languages



No explicit order of execution
Focus on defining target of the computation
through a set of functions of logic rules
Imperative Languages




Variety of data-structures
Support hierarchy (functions of procedures)
Support control-flow
Well-suited for modeling an algorithm
Winter-Spring 2001
Codesign of Embedded Systems
10
Models:
Programming Lang. (cont’d)

Main disadvantage

Do not explicitly model system states
Winter-Spring 2001
Codesign of Embedded Systems
11
Models:
Program-State Machines



Combination of HCFSM with PL
Consists of a hierarchy of Program-states
Program-states


Leaf / composite program-states
Composite program-state


concurrent / sequential program-substates
Sequential program-substates

Transition-on-Completion (TOC) arc / Transitionimmediately (TI) arc
Winter-Spring 2001
Codesign of Embedded Systems
12
What we learned today

We use Models to decompose systems into
pieces, then use Languages to generate a
specification of those pieces.

FSM, DFG, FSMD, HCFSM, PL, PSM, ...
Winter-Spring 2001
Codesign of Embedded Systems
13
Complementary notes:
Extra classes

“Compiler Design Short Course” by Gh. Jaberi-Pur



“HW Synthesis Techniques Seminar” by S. Safari



Date-Time: Thursday, Esfand 18th, 9-12 o’clock
Place:
Date-Time: Saturday, Esfand 20th, 13-14:30
Place
“HW design using RenoirTM workshop” by A. Ganjei


Date-Time:
Place:
Winter-Spring 2001
Codesign of Embedded Systems
14
Complementary notes (cont’d)



Assignment 1.c becomes optional
Course webpage is ready
Subscribe to course mailing list

Send an email from your desired email address to
[email protected] containing:
subscribe ce226list

Project

Choose and announce your partner for the final
project
Winter-Spring 2001
Codesign of Embedded Systems
15