RE: [sv-ac] New version of 3213

Hi Ben,

Please, see my comments below. I uploaded the updated version here: http://www.eda-stds.org/mantis/file_download.php?file_id=5141&type=bug

Thanks,
Dmitry

From: ben cohen [mailto:hdlcohen@gmail.com]
Sent: Tuesday, June 07, 2011 23:03
To: Korchemny, Dmitry
Cc: Kulshrestha, Manisha; sv-ac@eda-stds.org
Subject: Re: [sv-ac] New version of 3213

Dmitry,
Comments:
16.5.1 Sampling

* The default sampled value of a static variable is ...

 * The default sampled value of any other variable or net is the default value of the corresponding type ...
[Ben] In the 2nd bullet, you're addressing variables that are not "static", like the free variables and wires. But free variables can be initialized (e.g., rand logic r=0;); thus, it's default would be the value assigned in its declaration.
[Korchemny, Dmitry] Checker free variables are static. Why do you think they are not?

[LRM] rand bit a = 1'b0, b; The free variable a has initial value 0, but in other time steps its value may change
How about:

* The default sampled value of a static or free variable is the value assigned in its declaration, or, in the absence of such an assignment, it is the default (or uninitialized) value of the corresponding type (see 6.8, Table 6-7).

--
[3213] The notion of a default sampled value is used in the definition of a sampled value as explained below, and in the definition of sampled value functions when there is a need to reference a sampled value of an expression before time 0 (see 16.9.3).
[Ben] Consider the following editorial change.
A default sampled value is used in the definition of a sampled value of an expression as explained below, and in the definition of sampled value functions when there is a need to reference a sampled value of an expression before time 0 (see 16.9.3).
[Korchemny, Dmitry] Done.
--
[3213]  (see 16.5.1 for the definition of sampling in past clock ticks, and the description of $past below of how past values are evaluated.).
[Ben The "below" should be be bracketed with commas. How about
(see 16.5.1 for the definition of sampling in past clock ticks, and the description of $past, see below, of how past values are evaluated).
[Korchemny, Dmitry] Would it be sufficient to add a comma here?
(see 16.5.1 for the definition of sampling in past clock ticks, and the description of $past below, of how past values are evaluated.).
I would like to avoid having two "see" in the same sentence.
--
Ben
On Tue, Jun 7, 2011 at 7:44 AM, Korchemny, Dmitry <dmitry.korchemny@intel.com<mailto:dmitry.korchemny@intel.com>> wrote:
Hi Manisha,
Please, see my comments below.
Thanks,
Dmitry
From: Kulshrestha, Manisha [mailto:Manisha_Kulshrestha@mentor.com<mailto:Manisha_Kulshrestha@mentor.com>]
Sent: Friday, June 03, 2011 09:35
To: Korchemny, Dmitry; sv-ac@eda-stds.org<mailto:sv-ac@eda-stds.org>
Subject: RE: [sv-ac] New version of 3213
Hi Dimitry,
There are more comments:
1. In 16.5.1, I would prefer reordering few things. This section starts with sampled value of an expression but then starts discussing sampled values of variables and then goes back to sampled value of expressions. It would be good to first define sampled value of expressions. So move the section on sampled value of expression before sampled value of variables. Also, it is not clear when the default sampled value of expression is used. There is only statement about default sampled value of a variable "The sampled value of a variable in a time slot corresponding to time 0 is its default sampled value ". Probably a similar sentence is required for default sampled value of expressions also.
[Korchemny, Dmitry] I added several clarifications following your comments. However, if we want to define terms before their use, we need to keep the order of definitions: first to define the default sampled value, then the sampled value of a variable, which uses the notion of the default sampled value, and then the notion of the sampled value of an expression which is defined on top of the sampled value of a variable. The first sentences in this subclause provides the general insight to allow the reader to get a general understanding which is then refined in the further sentences.
2. In section 16.5.1, in sentence "When a past or a future value of an active checker variable is referenced by a sampled value function (see 16.9.3 and 16.9.4), this value ..", there should be 'active free checker variable'.
[Korchemny, Dmitry] Done.
3. The sentence "When a past or a future value of an automatic variable is referenced by a sampled value function, the current value of automatic variable is taken instead. " should also cover local variable (should pick the current value). This way the restriction about usage of local variables in sampled value functions will be removed.
[Korchemny, Dmitry] I am not sure about it. The past value of the local variable should be its previous value in this thread, and not its current value. Defining a past value of a local variable formally would require a significant effort, and its added value is not clear. I suggest not to deal with the past value of a local variable in this proposal.
4. In 16.15.6.1, it is not clear what happens to the saved sampeld value of automatic/const cast expressions.  May be the sentence should be extended like this "A procedural concurrent assertion shall not sample any const expression or automatic variable, but shall instead saves the sampled values of the its const expressions or and automatic variables at the time the assertion evaluation attempt is added to the procedural assertion queue. This assertion evaluation attempt uses these saved values for rest of the evaluation.
[Korchemny, Dmitry] Added this sentence.
5. In 17.3, there should be reference to 16.5.1 where sampled value is mentioned for actual arguments.
[Korchemny, Dmitry] Done.
6. In 17.7.2, the modified text should have 'active free checker variable'.
[Korchemny, Dmitry] This should be clear from the context as we are talking about checker variables in this subclause. Added in any case.
Thanks.
Manisha
________________________________
From: owner-sv-ac@eda.org<mailto:owner-sv-ac@eda.org> [mailto:owner-sv-ac@eda.org<mailto:owner-sv-ac@eda.org>] On Behalf Of Korchemny, Dmitry
Sent: Wednesday, June 01, 2011 6:10 PM
To: sv-ac@eda-stds.org<mailto:sv-ac@eda-stds.org>
Subject: [sv-ac] New version of 3213
Hi all,
I uploaded the new version of 3213: http://www.eda-twiki.org/mantis/file_download.php?file_id=5124&type=bug. Before calling to vote I would like to ask you to look at it and to send me your comments.
I modified the following sections:
*         16.5.1 Sampling
o   Replaced the term "initial sampled value" with "default sampled value"
o   Added a clarification about the definition of the sampled value returned by a function
o   Added a definition about handling past and future sampled values of automatic variables and constant expressions
*         16.9.3 Sampled value functions
o   Removed the restriction about automatic variable usage in sampled value functions
o   Added an example of $past(b[i]), where b is a design vector, and i is an automatic loop variable.
I intend to call to vote on it in a couple of days.
Thanks,
Dmitry
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