Re: [vhdl-200x] Relax locally static restrictions?

From: David Koontz <diogratia@gmail.com>
Date: Wed Apr 01 2015 - 21:24:09 PDT
On 1/04/2015, at 4:40 pm, Daniel Kho <daniel.kho@gmail.com> wrote:

> Hi all,
> I'm wondering if there is a reason to only allow locally static expressions in array aggregates? Why can't we pass generic constants from a higher level hierarchy to form the expressions for choices in array aggregates?
> 
> I find the LRM rather restrictive in how named associations of array aggregates are only "allowed to have a choice that is not locally static, or likewise a choice that is a null range, only if the aggregate includes a single element association and this element association has a single choice".
> 
> Is there some history on why such a restriction is in place?
> 
> ----------------------------------------------------------------------------------------------------------
> Section 9.3.3.3 Array aggregates
> Apart from a final element association with the single choice others, the rest (if any) of the element
> associations of an array aggregate shall be either all positional or all named. A named association of an array
> aggregate is allowed to have a choice that is not locally static, or likewise a choice that is a null range, only
> if the aggregate includes a single element association and this element association has a single choice. An
> others choice is locally static if the applicable index constraint is locally static.
> ----------------------------------------------------------------------------------------------------------

Well, there's 9.3.3.1 paragraph 6:

Each element of the value defined by an aggregate shall be represented once and only once in the aggregate.

 --

The restrictions have been in place since -1987.






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Received on Wed Apr 1 21:24:42 2015

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