RE: [sv-bc] 4-state or 2-state expression types

Also, Table 7-1, which specifies values to be returned from a non-existent array entry, already specifies that reading a non-existent 2-state element returns '0. More generally, a value is always returned that is in the value set of the corresponding data type. I find it questionable that 2-state integral types should be exceptions.

Shalom

> -----Original Message-----
> From: Jonathan Bromley [mailto:jonathanbromley@ymail.com]
> Sent: Wednesday, March 23, 2011 1:46 PM
> To: Bresticker, Shalom; Steven Sharp; Gordon Vreugdenhil; sv-bc
> Subject: Re: [sv-bc] 4-state or 2-state expression types
>
> I spoke a little too soon...
>
>
>
> > The two simulators I can try right now disagree about this. Doing
> an
> > out-of-range select on a 2-state vector, one yields 4-state 1'bx,
> the other
> > 2-state 1'b0.
>
> The third big-name simulator also yields a 2-state result.
>
> In fact the simulator that yielded 4-state 1'bx did so only when the
> subscript
> was statically known to be out of bounds (and it gave me an
> elaboration-time
> warning for that too). An out-of-bounds subscript computed at runtime
> gave
> 2-state 1'b0, just like the other simulator. I don't know whether that
> should
> affect BC's thinking...
>
> Jonathan Bromley
>
>
>
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