Re: [$ieee-1850] Backward compatibility with previous LRM

all,

another backward compatibility issue:

the keywords assume_guarantee and restrict_guarantee have been cancelled,
as per the decisions of group Q.1:

http://www.eda-stds.org/ieee-1850/Issues/Group-Q.1.html

cindy.




                                                                           
             Sitvanit                                                      
             Ruah/Haifa/IBM@IB                                             
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                                                                   Subject 
                                       [$ieee-1850] Backward compatibility 
             21/07/2009 15:38          with previous LRM                   
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           





Dear group,
Here is a summary regarding backward compatibility  with the previous LRM.

Incompatibility in constructs that were well defined in the previous LRM:
-----------------------------------------------------------------------------------------------------------

- The keyword "override" has been added, and its use is mandatory when one
wants to change the behavior of a signal.

- The formal semantics of structural contradiction was changed.
    For example in the previous LRM a trace with infinite number of b's
would give different truth values to {b[*];false} and to { b[*]; { {a} &&
{a;a} } }.
   In the new LRM this bug was fixed such that the same truth value will be
given to both. The incompatibility here is more theoretical than practical,
   because many tools probably already support the newer definition, as it
is the more natural one to implement.

Other well defined constructs remained unchanged.


Changes in constructs whose definition was ambiguous in the previous LRM
might have caused incompatibility if a company chose to implement another
interpretation of the construct.
These changes were necessary in order to have a unique interpretation in
all the entities supporting the standard.
The ambiguous definitions that changed and are now well defined:
-------------------------------------------------------------------------------------------------

- The definition of inheritance and overriding (section 7.2)


Regards,
Sitvanit

Sitvanit Ruah
Formal Verification Group
IBM Haifa Research Laboratory
Tel:  972-4-828-1249


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