Modeling timing constraints parameterized and multi clock systems in tadl2
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Modeling timing constraints, parameterized and multi-clock systems in TADL2. Johan Nordlander, Chalmers University of Technology. System models & constraints. A system model:. cost. timing. logical. resource usage. structural.

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Modeling timing constraints parameterized and multi clock systems in tadl2

Modeling timing constraints, parameterized and multi-clock systems in TADL2

Johan Nordlander, Chalmers University of Technology

AMST Workshop - Berlin


System models constraints
System models & constraints systems in TADL2

A system model:

cost...

timing...

logical...

resource usage...

structural...

Industry objective: specify / characterize / verify models using constraints

AMST Workshop - Berlin


Tadl2 timing augmented description language
TADL2 systems in TADL2(Timing Augmented Description Language)

A language of timing constraints (and timing constraints only)

TADL2

Constraints

Connecting points:

the events exposed

by a system model

Delay...

Periodic...

Model

AMST Workshop - Berlin


Events occurrences
Events & occurrences systems in TADL2

For each execution / simulation / prediction of a system,

every event occurs a some points in time.

time

TADL2 constraints

put demands on the

relative placement

of such occurrences

Model

AMST Workshop - Berlin


The need for semantic precision
The need for semantic precision systems in TADL2

Some well-known occurrence patterns:

  • But what about jitter?

  • What if jitter > period?

  • What if repetition stops?

Source-to-target delay

  • What if source repeats?

  • Can multipletarget occurrences match?

  • Are straytarget occurrences allowed?

Periodic repetition

Sporadic repetition

  • Is jitter meaningful here too?

  • Same as upper-lower difference?

  • Accumulating vs. non-accumulating drift?

AMST Workshop - Berlin


Delayconstraint
DelayConstraint systems in TADL2

duplicate and stray

occurrences allowed

source

lower

upper

target

time

DelayConstraint (source, target, lower, upper)xsource : ytarget : lower ≤ y – x ≤ upper

AMST Workshop - Berlin


Strongdelayconstraint
StrongDelayConstraint systems in TADL2

duplicate and stray

occurrences disallowed

(lock-step enforced)

1

2

3

source

lower

upper

target

1

2

3

time

StrongDelayConstraint (source, target, lower, upper)i : x : x=source(i) y : y = target(i) : lower ≤ y – x ≤ upper

AMST Workshop - Berlin


Reactionconstraint
ReactionConstraint systems in TADL2

only first related

response of interest

stimulus

minimum

maximum

scope

response

time

ReactionConstraint ( scope, minimum, maximum )xscope.stimulus : y scope.response : x.color = y.color (y’scope.response : y’.color = y.color y ≤ y’) minimum ≤ y – x ≤ maximum

AMST Workshop - Berlin


Tadl2 constraint overview
TADL2 constraint overview systems in TADL2

DelayConstraint (source, target, lower, upper)

StrongDelayConstraint (source, target, lower, upper)

RepetitionConstraint (event, lower, upper, span, jitter)

SynchronizationConstraint (event, tolerance)

StrongSynchronizationConstraint (event, tolerance)

ExecutionTimeConstraint (start, stop, preempt, resume, lower, upper)

OrderConstraint (source, target)

ComparisonConstraint (leftOperand, rightOperand, operator)

SporadicConstraint (event, lower, upper, jitter, minimum)

PeriodicConstraint (event, period, jitter, minimum)

PatternConstraint (event, period, offset, jitter, minimum)

ArbitraryConstraint (event, minimum, maximum)

BurstConstraint (event, length, maxOccurrences, minimum)

ReactionConstraint (scope, minimum, maximum)

AgeConstraint (scope, minimum, maximum)

OutputSynchronizationConstraint (scope, tolerance)

InputSynchronizationConstraint (scope, tolerance)

+ mode-dependency

parameter (optional)

AMST Workshop - Berlin


A mode dependent delayconstraint
A mode-dependent DelayConstraint systems in TADL2

M

source

lower

upper

target

time

Not satisfied overall...

start(M)

... but quite ok when

restricted to mode M!

stop(M)

(a mode is defined by its start- and stop-events)

AMST Workshop - Berlin


A borderline mode example
A borderline mode-example systems in TADL2

Should this trace be accepted by the mode-dependent DelayConstraint?

M

There’s no matching

target occurrence

inside M...

source

lower

upper

target

time

... but a matching

occurrence is still

possible outsideM

(where we don’t look!)

start(M)

stop(M)

TADL2 thus chooses to answers yes! (the optimistic assumption)

AMST Workshop - Berlin


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