Re: [sv-bc] Sign of a signed packed array of struct

See also

  http://www.eda.org/svdb/view.php?id=1291
<http://www.eda.org/svdb/view.php?id=1291>

On Fri, Sep 10, 2010 at 8:50 PM, Steven Sharp <sharp@cadence.com> wrote:

>
> >From: John Michael Williams <jwill@basicisp.net>
>
> >An array is an unordered set, and it does not represent a quantity,
> >so I think it could not be either signed or unsigned.
>
> A packed array, such as this one, is an ordered set that represents
> a quantity, and can be either signed or unsigned.
>
> In this case, I believe the answer is that S is unsigned, and S[0]
> is signed. I will have to dig deeper into the spec for support for
> this.
>
> For a packed array of packed arrays, you can use typedefs to make any
> one of the levels of selects signed, but only one of them. If you use
>
> logic signed [3:0] [3:0] S;
>
> then S is signed, and S[0] is unsigned. If you use
>
> typedef signed [3:0] s_nibble;
> s_nibble [3:0] S;
>
> then S is unsigned, and S[0] is signed. You cannot make both of them
> signed, which is a shortcoming of the language.
>
> In the array of structs case, I think you can only make the struct signed.
> I don't think there is a way to make the full array vector signed if it
> is composed of packed structs.
>
>
> Steven Sharp | Architect | Cadence
>
> P: 508.459.1436 M: 774.535.4149 www.cadence.com
>
>
>
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