Geoffrey,
I was trying to work from the original
text and apparently got myself in a bigger mess :-)
I agree with your proposal although
I have the impression that the LRM makes a distinction between assignment
which is done when providing a default value and overriding the default
values by either a defparam, instance parameter override by position or
instance parameter override by name. Your first proposed bullet (An array
assigned ...) should probably also mention the assignment of the default
value for an array parameter.
The equivalent type was put in as in
case of integer vs real arrays coercion can be used, in case of a string
array (do have those?) it can't be done. Or put in other words, each array
element is assigned a value as though it were a scalar initialized by a
scalar constant.
It allows:
parameter
real pwl[0:3] = {0, 0, 1, 1}; // initialize real array with integer values
It disallows:
parameter
integer active[0:1] = { "yes", "no" };
Cheers,
Marq
Research
NXP Semiconductors
"Geoffrey.Coram" <Geoffrey.Coram@analog.com>
Sent by:
geoffrey.coram@analog.com
19-04-2007 13:23
|
|
To
| Marq Kole <marq.kole@nxp.com>
|
|
cc
| verilog-ams <verilog-ams@eda-stds.org>
|
|
Subject
| Re: array parameters overrides
|
|
Classification
| |
|
Marq -
The existing bullet says:
* An array assigned to an instance of a module shall be of the exact size
of the array bounds of that instance
This seems to say what you needed it to say for the examples
you sent earlier (trying to override the array parameter
with shorter or longer arrays). I don't see how your
proposed text helps, unless you are saying that "assigned
to an instance of a module" isn't precise, since it doesn't
make clear that "assigning to an instance" is really meant
to be overriding the default value.
"array bounds of that instance" is a little odd, also, since
the "instance" doesn't have array bounds, only the parameter.
I will also note that "equivalent type" isn't necessary; one
could
have coercion (real to integer or vice-versa). Perhaps, though,
we should say something about strings.
How about:
* An array assigned to an instance of a module to override the
default value of an array parameter shall be of the exact size
of the parameter array, as determined by its declaration.
* Since array range in the parameter array declaration may
depend on previously-declared parameters, the array size
can be changed by overriding the appropriate parameters.
If the array size is changed, the parameter array shall be
assigned an array of the new size from the same module
as the parameter assignment that changed the parameter
array size.
-Geoffrey
Marq Kole wrote:
>
> All,
>
> I propose the following text to replace the second bullet in the list
in section 3.2.4 (Parameter Arrays):
>
> * An array assigned to an instance of a module or overriding
the default value of an array parameter in an instance of a module shall
be of the exact size as defined by the array bounds of that instance parameter.
Assigning to an array requires also that each element to be of an equivalent
type.
>
> Cheers,
> Marq
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Received on Thu Apr 19 04:44:27 2007