Essential Issues in Codesign Models Part of HWSW

Essential Issues in Codesign: Models Part of HW/SW Codesign of Embedded Systems Course (CE 40 -226) 11/07/42 Winter. Spring 2001 Codesign of Embedded Systems 1

Today programme n Essential issues in codesign n Models n Architectures n Languages Winter-Spring 2001 Codesign of Embedded Systems 2

Models n Model should be n n Formal => avoid ambiguity Complete => can describe entire system Comprehensible and easy-to-modify Model vs. Language n n 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) n n n A set of states and a set of transitions between them Most popular model for control systems Formal definition n n <S, I, O, f, h> Depending on output function (h) n Mealy machine / Moore machine Winter-Spring 2001 Codesign of Embedded Systems 4

Models: Dataflow Graph (DFG) n n Most popular model for computation-intensive systems Its basic principles n n n 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 <N, A, V, v 0, f> Winter-Spring 2001 Codesign of Embedded Systems 5

Models: FSM with Datapath (FSMD) n n n Both control and computation are required in most systems FSMD is a combination of FSM and DFG models Formal definition n <S, I, O, f, h> f = {f. C, f. D} h= {h. C, h. D} Winter-Spring 2001 Codesign of Embedded Systems 6

Models: FSM with Datapath (cont’d) n Neither FSM nor FSMD are suitable for complex systems n Concurrency n n Explosion in states Hierarchy n Explosion in arcs Winter-Spring 2001 Codesign of Embedded Systems 7

Models: Hierarchical Concurrent FSMs n n n 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 n Heterogeneous model n n support data, and control modeling Major PL types n Imperative (C, Pascal) n n Control-driven model of execution Declarative n Demand-driven / Pattern-driven model of execution Winter-Spring 2001 Codesign of Embedded Systems 9

Models: Programming Lang. (cont’d) n Declarative languages n n n No explicit order of execution Focus on defining target of the computation through a set of functions of logic rules Imperative Languages n n 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) n Main disadvantage n Do not explicitly model system states Winter-Spring 2001 Codesign of Embedded Systems 11

Models: Program-State Machines n n n Combination of HCFSM with PL Consists of a hierarchy of Program-states n n Leaf / composite program-states Composite program-state n n concurrent / sequential program-substates Sequential program-substates n Transition-on-Completion (TOC) arc / Transitionimmediately (TI) arc Winter-Spring 2001 Codesign of Embedded Systems 12

What we learned today n We use Models to decompose systems into pieces, then use Languages to generate a specification of those pieces. n FSM, DFG, FSMD, HCFSM, PL, PSM, . . . Winter-Spring 2001 Codesign of Embedded Systems 13

Complementary notes: Extra classes n “Compiler Design Short Course” by Gh. Jaberi-Pur n n n “HW Synthesis Techniques Seminar” by S. Safari n n n Date-Time: Thursday, Esfand 18 th, 9 -12 o’clock Place: Date-Time: Saturday, Esfand 20 th, 13 -14: 30 Place “HW design using Renoir. TM workshop” by A. Ganjei n n Date-Time: Place: Winter-Spring 2001 Codesign of Embedded Systems 14

Complementary notes (cont’d) n n n Assignment 1. c becomes optional Course webpage is ready Subscribe to course mailing list n Send an email from your desired email address to majordomo@ce. sharif. edu containing: subscribe ce 226 list n Project n Choose and announce your partner for the final project Winter-Spring 2001 Codesign of Embedded Systems 15