Synchronous Methodology for Hardware, Software, and Mixed Embedded Systems

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Synchronous Methodology for Hardware, Software,
and Mixed Embedded Systems
Part 4 formal verification and test generation
Gérard Berry
Chief Scientist www.esterel-technologies.com G
erard.Berry_at_esterel-technologies.com
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Agenda - Part 4Formal Verification and Test
Generation

• FV principle observers
• FV engines BDD and SAT
• Sequential equivalence
• Demos

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Verification by Observers
OK
Prog
Obs
Env
E
BUG
For all input sequence that are OK, the observer
never reports BUG
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Automated Verification
1. Using explicit flat automata Auto, TempEst
(Bell Labs)
2. Using circuits and BDDs Xeve, SMV (Cadence)
3. Using circuits and SAT engines Prover
Technologies
4. Coverage analysis / test pattern generation A.
Bouali (INRIA - Esterel Technologies) L. Arditi
(Texas Instruments)
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BDD-based techniques

• Only deals with the control part
• gt data is abstracted away
• Efficient for reachable state space computation
• gt property verification
• Efficient for solution enumeration
• gt automatic test generation

Example the elevator controller
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SAT-based engines

• Very efficient for bug chasing
• try all sequences of length 1,2,...
• Handles data and control (Prover SL 2.1)
• Yet less efficient for full verification
• does not compute the diameter of the design
• halting test difficult
• (but see recent work by McMillan)

Examples CRC, UART
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Sequential Equivalence
Compare two designs for full sequential behavior
equality

• Three usage models
• Safe rewrite of modules to make them better
  coded
• no need to be afraid to make changes when
  behavior OK!
• Validation of full synthesis path by source /
  gate list equivalence
• Validation of late Engineering Change Orders
  (ECOs)

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Overall Conclusion

• Synchronous programming is well-adapted for
  embedded
• software and hardware
• Synchronous languages have fully formal
  semantics and
• efficient synthesis
• They support formal verification and test
  generation
• They are now becoming widely used in Industry