RE: [sv-ac] Mantis 1698

Hi Lisa,

 

The symbol '<=' is used for nonblocking assignments.  But the language
says that it executes in the active region. Do you mean that the always
block executes in active region or the assignment happens in active
region ? 

 

It talks about certain regions where $past is replaced by
$sampled(past_variable). What about other regions ? 

 

Thanks.

Manisha

 

From: owner-sv-ac@server.eda.org [mailto:owner-sv-ac@server.eda.org] On
Behalf Of Lisa Piper
Sent: Tuesday, January 29, 2008 11:50 PM
To: Eduard Cerny; sv-ac@server.eda.org
Subject: RE: [sv-ac] Mantis 1698

 

That is what I started with but then had to get rid of all references to
synthesis. I thought I was combining the last sentence into the first
sentence, but I ended up losing it.  Does this work?

 

Regardless where $past(x,,,@clk) is called from, the RTL equivalent is

 

     always @clk past_variable <= $sampled(x);

 

and executes in the active region.

 

If $past is called from active, reactive or observed regions, replace

the call by $sampled(past_variable).

 

-----Original Message-----
From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On Behalf Of
Eduard Cerny
Sent: Tuesday, January 29, 2008 12:32 PM
To: sv-ac@eda.org
Subject: [sv-ac] Mantis 1698

 

Hi to start the discussion, I copy here the note I put on mantis 1698

quite a while ago. Could that be used?

 

---

Regardless where $past(x,,,@clk) is called from, the RTL equivalent is

 

always @clk past_variable <= $sampled(x);

 

and executes in the active region.

 

If $past is called from active, reactive or observed regions, replace

the call by $sampled(past_variable).

 

In synthesized code which executes in the active region, use the

past_variable directly. Provided that the model follows synthesis rules

and is not racy, the behavior should be equivalent to that in the

original model using $past.

 

The other functions, $rose, $fell and $stable would follow. 

 

----

 

Best...

ed

 

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