Re: [vhdl-200x] Iterating across a Record Type

Hi Daniel,

Actually, the first probably deals more with the problem and how to achieve it.

It has been merged for tracking reasons, but is entitled:

    Record Introspection & Indexing

and proposes an implicit enumerated type generated when a record is declared. 
The elements are accessed using the same attribute.

Brent


On 05/06/2014 17:31, Daniel Kho wrote:
> Hi Martin,
> Thanks, I believe the Record Introspection proposal is what I'm looking for.
>
> Cheers, Dan
>
>
> On 5 June 2014 16:05, Martin.J Thompson <Martin.J.Thompson@trw.com 
> <mailto:Martin.J.Thompson@trw.com>> wrote:
>
>     Daniel,
>
>     Do these proposals not meet your needs?
>
>     http://www.eda-twiki.org/cgi-bin/view.cgi/P1076/RecordMemberAttribute
>
>     http://www.eda-twiki.org/cgi-bin/view.cgi/P1076/RecordIntrospection
>
>     The latter one provides “for element in record_type'elements loop“ which looks like it would work for you?
>
>       
>
>     Cheers,
>     Martin
>
>     *From:*owner-vhdl-200x@eda.org <mailto:owner-vhdl-200x@eda.org>
>     [mailto:owner-vhdl-200x@eda.org <mailto:owner-vhdl-200x@eda.org>] *On
>     Behalf Of *Daniel Kho
>     *Sent:* 05 June 2014 05:15
>     *To:* vhdl-200x@eda.org <mailto:vhdl-200x@eda.org>
>     *Subject:* [vhdl-200x] Iterating across a Record Type
>
>     Hi friends,
>
>     I know this question has been asked before in some forums, but I feel it
>     hasn't been adequately answered. My intent is to loop across all elements
>     of a record type, similar to how we could do it with an array:
>
>     for i in vect'range loop
>
>     vect(i)<=i;
>
>     end loop;
>
>     where "vect" is an array vector of naturals for example.
>
>     The question is, if I had a record type with several sub-elements, how
>     would I be able to iterate across all the sub-elements? For example,
>     assume we have a record:
>
>     type rec is record
>
>     a:std_ulogic;
>
>     b:std_ulogic_vector(15 downto 0);
>
>     c:signed(7 downto 0);
>
>     end record rec;
>
>     I prefer to not have to write out all the sub-elements individually:
>
>     function resolve(r:rec) return rec is begin
>
>         if is_x(r.a) then ... end if;
>
>         if is_x(r.b) then ... end if;
>
>         if is_x(r.c) then ... end if;
>     end function resolve;
>
>     Currently, I feel having an option for iterating across record structures
>     will be very useful especially when writing resolution functions, but I
>     believe this usefulness can be applied to many other scenarios as well.
>     Another application I can think of which makes having such a feature
>     useful, is to apply them for initializers.
>
>     Some languages (e.g. scripting languages) have something like "child" or
>     "next" keywords which we can use to access neighbouring elements of a
>     structure. I was thinking of having something like this for VHDL:
>
>     function resolve(r:rec) return rec is begin
>
>         for i in r'range loop    -- okay, 'range only works for arrays now,
>                                        -- but you get the idea.
>
>             if is_x(r.child(i)) then ... end if;
>
>         end loop;
>
>     end function resolve;
>
>     Of course, "child" may as well be some other keyword, e.g. "element", or
>     picked from a suitable existing VHDL keyword.
>
>     Best regards,
>     Daniel
>
>
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-- 

Regards,

         Brent Hayhoe.

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