Re: Fw: Contributions (was Re: disallow distributed switch branches)

From: Kevin Cameron <kevin_at_.....>
Date: Mon May 07 2007 - 09:29:19 PDT
Geoffrey.Coram wrote:
> Kevin Cameron wrote:
>   
>>>>> What do you mean moot?  The other form you show is an indirect
>>>>> assignment, and the LRM presently contains restrictions against
>>>>> using those along with direct contributions.
>>>>>           
>>>>       
>>>> That restriction only applies within a single analog block.
>>>> Contributions via OOMR and ports are not restricted that way (the driver
>>>> of the OOMR is a different block-instance).
>>>>         
>>> At the end of Chapter 5 (5.3.2.2): "It is illegal to indirectly
>>> assign to an external branch or contribute to an external branch
>>> which has an indirect branch assignment."
>>>
>>>       
>> That's probably wrong/unnecessary. There is a rewrite rule for
>> converting indirect assignments to contributions, so no reason for not
>> mixing them across blocks.
>>     
>
> Kevin -
> Your last comment is not helpful at this point.  You made an
> assertion, I cited the rule from the LRM, and then you say,
> oh, well, the LRM is wrong. 

>  No, the LRM defines the standard!
>   

Doesn't mean it's not wrong. I think pointing out that it is wrong is 
helpful too.

> The committee reviewed this section last April, and you had nothing
> to say then.  If you have a complete algorithm for converting
> indirect assignments to contributions that works in all situations
> and yields the same answers (including tolerances), you are welcome
> to submit the proposal as a Mantis item.
>   

When I worked on the Verilog-A simulator at MetaSoftware we handled the 
indirect assignments by doing an internal rewrite to a form that matched 
how the contributions worked. The only necessary restriction is that you 
can't mix contribution with indirect assignment within a single analog 
block. Maybe the LRM rule stems from an inadequacy in someone's 
simulator, but it seems more likely it's just wasn't written up properly.

Kev.

> -Geoffrey
>   


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Received on Mon May 7 09:29:34 2007

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