RE: [sv-bc] E-mail Vote: Closes 12am PST Nov 17

> Unless you
> think that casting an object to TypeA as another TypeA should alter
> some bits? Could you elaborate on your doubts about assignment
> compatible vs equivalence here?

The description of array assignment in section 4.7 describes it as taking
place element by element.

The description of bit-stream casting in section 3.16 says that all the
bits of the source are put into a single bit stream, and then this bit
stream is converted to the target type. It then says:

"If the destination type, dest_t, includes unbounded dynamically-sized
types, the conversion process is greedy: compute the size of the source_t,
subtract the size of the fixed-size data items in the destination, and then
adjust the size of the first dynamically sized item in the destination to
the remaining size; any remaining dynamically-sized items are left empty."

I think this means all of data from all the 'a' fields of different elements
of source array will end up in the 'a' field of the first element of the target.
This is completely different than an element by element assignment, in addition
to not being very useful.

> -----Original Message-----
> From: Greg Jaxon [mailto:Jaxon@synopsys.COM]
> Sent: Tuesday, November 16, 2004 3:54 PM
> To: Mark Hartoog
> Cc: Maidment, Matthew R; sv-bc@eda.org
> Subject: Re: [sv-bc] E-mail Vote: Closes 12am PST Nov 17
>
>
> Mark Hartoog wrote:
>
> > 291 ___Yes _x_No
> > http://www.eda.org/svdb/bug_view_page.php?bug_id=0000291
> > I have no problem with the clarification of the assignment order,
> > but on the change from assignment compatible elements to type equivalent
> > elements, I am concerned that we have completely changed direction on the
> > issues of array assignment and casting several times over the last
> > year. The argument is we need to make these changes to be consistent
> > with bit stream casting, but I am not convinced that the current
> > description of bit stream casting makes sense, particularly
> > concerning dynamic types. Consider this case:
> >
> > typedef struct ( byte a[]; } ST;
> > typedef ST TypeA[0:1];
> > TypeA a;
> > TypeA b;
> >
> > I think
> >
> > a = b;
> >
> > and
> > a = TypeA'(b);
> >
> > do completely different things both with and without this change.
>
> Perhaps their internal workings differ, but the net effect is that
> every bit of b winds up in an equivalent position in a. Unless you
> think that casting an object to TypeA as another TypeA should alter
> some bits? Could you elaborate on your doubts about assignment
> compatible vs equivalence here?
>
> Greg
>
>
>
Received on Tue Nov 16 16:10:30 2004