Re: [sv-ac] [Fwd: Clock flow in SV assertion]

From: Surya Pratik Saha <spsaha_at_.....>
Date: Wed Mar 08 2006 - 05:12:25 PST
Hi John,
Even if I dont consider @ as operator, I have to know the precedence to implement sequence/property expression in an yacc file. And also the LRM has the following rule:

property_expr ::=
sequence_expr
...
| clocking_event property_expr

So in which context an item will be reduced with "clocking_event property_expr" has to be well defined.

LRM is not clear on that.

John Havlicek wrote:

Surya:

> Some days ago I asked the precedence of @ operator in assertion rule.
> I did not get well defined answer, however by reading the clock flow section,
> it is understood that @ has the weakest precedence.

Ed answered you that "@" is not an assertion expression operator,
so your line of reasoning to deduce that the LRM example

> @(posedge clk) a ##1 @(posedge clk1) s1 |=> @(posedge clk2) s2;

is wrong is flawed.

I will repeat Ed's answer:  in SVA, "@" is not an expression
operator.

Best regards,

John H.

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> &nbsp;
> <p>-------- Original Message --------
> <table BORDER=0 CELLSPACING=0 CELLPADDING=0 >
> <tr>
> <th ALIGN=RIGHT VALIGN=BASELINE NOWRAP>Subject:&nbsp;</th>
>
> <td>Clock flow in SV assertion</td>
> </tr>
>
> <tr>
> <th ALIGN=RIGHT VALIGN=BASELINE NOWRAP>Date:&nbsp;</th>
>
> <td>Wed, 08 Mar 2006 10:28:44 +0530</td>
> </tr>
>
> <tr>
> <th ALIGN=RIGHT VALIGN=BASELINE NOWRAP>From:&nbsp;</th>
>
> <td>Surya Pratik Saha &lt;spsaha@cal.interrasystems.com></td>
> </tr>
>
> <tr>
> <th ALIGN=RIGHT VALIGN=BASELINE NOWRAP>To:&nbsp;</th>
>
> <td>"sv-bc@eda.org" &lt;sv-bc@eda.org>, sv-ac@eda.org</td>
> </tr>
> </table>
>
> <p>Hi,
> <br>Some days ago I asked the precedence of @ operator in assertion rule.
> I did not get well defined answer, however by reading the clock flow section,
> it is understood that @ has the weakest precedence.
> <p>Considering the fact the given e.g. in LRM (page no. 282, e.g. d)
> <p>@(posedge clk) a ##1 @(posedge clk1) s1 |=> @(posedge clk2) s2;
> <p>will be parsed as:
> <p>@(posedge clk) a ##1 (@(posedge clk1) s1 |=> @(posedge clk2) s2);
> <p>So (@(posedge clk1) s1 |=> @(posedge clk2) s2) will become a property
> expression.
> <p>But as per assertion BNF, ## operator can not have property expression
> in RHS. So the e.g. given in LRM is wrong.
> <p>Please confirm.
> <pre>--&nbsp;
> Regards
> Surya.</pre>
> &nbsp;</html>
>

-- 
Regards
Surya.
  Received on Wed Mar 8 05:11:25 2006

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