Specification Languages Presented by Cecilia Ekelin Purpose of the - - PowerPoint PPT Presentation

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Specification Languages Presented by Cecilia Ekelin Purpose of the - - PowerPoint PPT Presentation

Apr 30, 2023 330 likes •561 views

Specification Languages Presented by Cecilia Ekelin Purpose of the language To express the specification of the system to be designed To enable formal reasoning about the design To provide possibilities for tool support on modeling,

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Specification Languages

Presented by Cecilia Ekelin

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Purpose of the language

To express the specification of the system to be designed To enable formal reasoning about the design To provide possibilities for tool support on modeling, validation and

implementation

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Implications on language design

A high-level approach necessary to cope with system complexity
  • Should be possible to express typical concepts
The language should be based on formal semantics (Models of Computation)
  • No assumptions about implementation
Formal syntax required as input to tools
  • Should be intuitive to the user
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Concepts of embedded systems

Concurrency
  • Interleaved vs Parallel
  • Control vs Data oriented
Hierarchy
  • Behavioral vs Structural
Communication
  • Message passing vs Shared memory
Synchronization
  • Synchronous vs Asynchronous
Implementation
  • Software vs Hardware
Time ?
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Models of computation

Synchronization (Communication)
  • Single vs Multi-thread
Concurrency (Functionality)
  • Data vs Control-driven

Representations: language-oriented (graphs), architecture-oriented (FSM)

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Languages

VLSI System Design:

Hardware abstraction levels, timing and data flow computations Hardware Description Languages (HDLs) E.g., VHDL, HardwareC, SpecCharts, SpecC
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Languages (continued)

Protocol specification:

Formal description to enable verification LOTOS
  • Based on process algebra and abstract data types
  • Specification is executable
SDL
  • Based on extended FSMs
  • Both graphical and textual modeling
ESTELLE
  • Pascal-like programming language
  • Implementation details necessary
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Languages (continued)

Reactive (real-time) system design:

Need to guarantee (timely) response to events ESTEREL
  • Based on events
  • Synchronous time model
LUSTRE, SIGNAL
  • Based on programmable automaton
  • Simple time aspects in LUSTRE but more advanced in SIGNAL
Petri net tools
  • Based on Petri nets
  • Not always formally defined
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Languages (continued)

Programming languages:

Often lacking constructs for concurrency and timing Extensions break the language standards E.g., C, Ada, Java, Fortran
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Languages (continued)

Formal methods:

Offers high abstraction but perhaps not all necessary concepts VDM, Z
  • Based on set theory and predicate logic
  • “Lack of tools” (www.ifad.dk)
B
  • Based on Abstract Machine Notation
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Languages (continued)

Structural Analysis:

Systematic approach for structuring code and data in software systems “Divide and conquer” E.g., OO, UML
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Languages (continued)

Continuous languages:

High-level modeling based on differential equations Used for DSP

, mechanical and hydraulic design

Large expressiveness makes verification and synthesis hard E.g., Matlab, Matrixx, Mathematica
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Case Study: SDL

Hierarchy

System Block Process Procedures
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Case Study: SDL (continued)

Communication & Concurrency

No global data Asynchronous signals Synchronous RPC:s Channels interface blocks and processes A signal is sent to an explicit process instances
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Case Study: SDL (continued)

Time

time and duration A process may start timers Timeouts are received as signals Timing can be simulated before implementation
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Case Study: SDL (continued)

Implementation

Data is described using ADT or ASN.1 Easily converted to other languages Reuse possible
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Tool support

Editor Simulator Proover Debugger Prototyper
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Heterogeneous modeling

Different phases (specification, design, implementation) Different subsystems (protocols, signal processing, control tasks)

Multilanguage design: Select language for each component and perform integrated validation

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Multilanguage validation

Independent approach
  • Individual validation
Integrated (compositional) approach
  • Translate each language into a general representation on which validation is

performed

  • E.g., Polis environment which is based on Codesign FSM
Coordinated (cosimulation) approach
  • Validate each component separately but within a common framework
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Cosimulation models

Data model
  • User-defined types ?
Timing model
  • No time (functional validation)
  • Time (granularity)
Synchronization (communication) model
  • Master-slave (direct connection)
  • Distributed (software “bus”)
Interfaces
  • In framework and implementation
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Example - Automotive application

Three levels: system, system architecture, cycle

System: Electronics (SDL) and Mechanics (Matlab)
  • Determines external specification
Architecture: Hardware (VHDL) and Software (C)
  • Validates partitioning and communication protocols
Cycle: Gates and Binary code
  • Verifies timing behavior

Prototyping

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Comments

“Performance” measures (development, usability, turn-around time, cost) Generalization (tools, concepts)