Essential Issues in Codesign: Models

1. Essential Issues in Codesign:Models Part of HW/SW Codesign of Embedded Systems Course (CE 40-226) Codesign of Embedded Systems

2. Today programme • Essential issues in codesign • Models • Architectures • Languages Codesign of Embedded Systems

3. 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) Codesign of Embedded Systems

4. 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 Codesign of Embedded Systems

5. 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> Codesign of Embedded Systems

6. 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} Codesign of Embedded Systems

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

8. 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 Codesign of Embedded Systems

9. 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 Codesign of Embedded Systems

10. 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 Codesign of Embedded Systems

11. Models:Programming Lang. (cont’d) • Main disadvantage • Do not explicitly model system states Codesign of Embedded Systems

12. 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 / Transition-immediately (TI) arc Codesign of Embedded Systems

13. 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, ... Codesign of Embedded Systems

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

15. 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 majordomo@ce.sharif.edu containing:subscribe ce226list • Project • Choose and announce your partner for the final project Codesign of Embedded Systems