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

7.4.1 says,

"If a packed array is declared as signed, then the array viewed as a single vector shall be signed. The individual elements of the array are unsigned unless they are of a named type declared as signed. A part-select of a packed array shall be unsigned."

So I would assume S to be signed and S[0] as unsigned.

Shalom

> -----Original Message-----
> From: owner-sv-bc@eda.org [mailto:owner-sv-bc@eda.org] On Behalf Of
> Steven Sharp
> Sent: Saturday, September 11, 2010 6:51 AM
> To: sv-bc@eda.org; jwill@BasicISP.net
> Subject: Re: [sv-bc] Sign of a signed packed array of struct
>
>
> >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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