(r1) 2007-10-12-Minutes < P1778

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---+ October 12 2007 - P1778 workgroup Meeting Minutes

   * Workgroup:  P1778 - Esterel v7 language standardization
   * Location:   Teleconference (see [[Next Meeting]] to connect)
   * Date:       12 Oct 2007
   * Chair:      Gerard Berry
   * Vice Chair: Stephen Edwards
   * Secretary:  Sylvan Dissoubray

---++ Attendance

   * Eric Badi, Claus Traulsen, Charles Andre, S. Ramesh, R.K. Shyamasundar, Gerard Berry, Marc Perreaut, Reinhard von Hanxleden, Sylvan Dissoubray, Marc Duranton, Luigi Zaffalon, Stephen Edwards, Raphael Bernhard, Badr Bentaybi, Jean-Philippe Cousin, Klaus Schneider, Mike Kishinevsky, Robert de Simone, 

   * See [[Attendance Record]] for meetings participation history


---++ Agenda


---++ Process

   * *Start*: Chair declares the meeting open at 5:05
   * *Agenda*: The agenda is approved by participants
   * *Minutes*: No objections about last meeting minutes -- they are approved
   * *Patents*: No new item . The page [[IEEE Patent Policy]] holds the call for patent, and workgroup status.

---++ Technical topics

_Brief summary of discussion, pros and cons, and conclusions_


---+++ Specific Working Groups Organization

   * WG1 : Data, arithmetic, and expressions
      * Eric Badi, Gerard Berry, Stephen Edwards, Mike Kishinevsky, Marc Perreaut (organizer), Klaus Schneider.

   * WG2 : signals, interfaces, ports
      * Eric Badi, Badr Bentaybi, Gerard Berry (organizer), Jean-Philippe Cousin,  Reinhard von Hanxleden, Klaus Schneider, Claus Traulsen,. 

   * WG3 : inheritance, genericity

   * WG4 : Tasking

      * Raphael Bernhard (organizer), Gerard Berry, Luigi Zaffalon

---+++ IEEE-Format Data and Arithmetic chapters

Three chapters have been written in IEEE format by Marc Perreaut, Data, Arithmetic, and Signals. They have been put on the Wiki mid-August but not yet reviewed by all participants. 

   * *Data chapter* put in IEEE style, not all change proposals have been incorporated yet
   * *Arithmetic chapter* idem

---+++ A new proposal for Esterel v7 signals

See [[http://esterelv7.esterel-technologies.com/index.php/New_proposal_for_signal_declarations][New proposal for signal declaration]]

---+++ Value signals

MK: replace init / default with and operator, e.g. '':=''

---+++ Maintained values

CA: ''Eventually maintained'' as a better naming than ''semi-maintained''

MK: or ''always defined'' and ''eventually defined''. '''Approved'''. To be added to glossary.

---+++ Control signals

CA: pre1 also available for control? Yes

RDS: opposite of ''control'' is usually called ''data'', better than ''value'' for hardware people. MK: OK. Approved.
''data'' and ''control'' signals to be added in glossary.

---+++ Controlled signals 

CA: why not have a special naming for the clock associated with the control signal. See later.

MK: Should control signals be simply called signals like before. TB analyzed.

RvH: Should we allow declaration of "full" signals (simultaneous declaration of control and data signals)?
Because it is painful to declare a second name for the control of a controlled signal?
But how to disambiguate the control and the data for such a signal (currently done by using '?' for the data)?
To be analyzed and decided.

N.B. In ''output X when X_change'', X_change is an output control.

---+++ Controlled signals arrays

Decision point about Claus comment. '''We miss this comment here.'''

---+++ Port value and assignment

NB. right hand side can be another port, or a struct being the result of a function call.

<verbatim>
 emit P <= {X_change: false, X: 3}
</verbatim>

This does no emission of the data signal X, (and no error either). NB the false status can be the result of a computation .

NB. struct are unordered. 

SE: Problem if structs partially share names. OCAML makes the choice that names are globally unique to solve it, which is awkward.
To be analyzed.

---+++ A shorthand to test the control

Before, you had X and ?X now you have @X and X (but there are much less @ than ? in programs).
In HW designs, data signals are generally more frequently used than control signals.

Actually ?S would be a natural name control of S, unfortunately it would be a rather confusing change.

---+++ Questions

RB: Is there a danger of making software more complex when simplifying hardware design ?

A page for the document discussion to be added.

Reinhard von Hanxleden. Have a glossary, with mapping to previous notions to ascertain terminology.

---+++ Inheritance and Genericity

   * See [[http://esterelv7.esterel-technologies.com/index.php/Module_Behavior_Inheritance][Module inheritance proposal]]


SE: Difference between module wo body and interface

GB: Interface is not equal to module headers, which have refinements. Module without body is a module headers, while interfaces are just pin lists with directions and types/sorts, no dynamic properties. You can mirror an interface, you can not mirror a registered signal.

SE: not convinced.

GB to add examples on this topic.


---++ Adjournment and Next meeting date

Next meeting will be decided by email

Meeting is closed at 6:37 PM.
Topic revision: r1 - 2008-09-23 - 15:24:13 - TWikiGuest
P1778