RE: [sv-ec] More clocking block issues

Dave,

 

I have always assumed that for an output clockvar, there is always an
internal memory that holds the value driven. The value must be held when
the drive takes place away from the active edge (or as Doug writes "in
the middle of the cycle"). This is true even when the target is a
variable.

 

            Arturo

 

________________________________

From: owner-sv-ec@eda.org [mailto:owner-sv-ec@eda.org] On Behalf Of
Rich, Dave
Sent: Tuesday, April 10, 2007 5:41 PM
To: sv-ec@eda.org
Subject: [sv-ec] More clocking block issues

 

And you all thought we were done...

 

A couple of issues have come up that I thought we had addressed, but I
can't seem to find it in the 890 proposal

 

1.	If I have a clockvar output whose target is a variable bit
vector, and within a given clock cycle I only drive a part or bit select
of that clockvar, do the undriven bits use their previous value? Mantis
890 makes it clear that for a net, an internal variable holds the
previous state of the clockvar until a new value is driven, but there is
no such wording for driving a target that is a variable.
2.	A similar question for unpacked structs and arrays: If a member
of an unpacked type is selected in a clockvar drive, then should the
entire target variable be assigned with previous values of all the other
clockvar members?

 

 

 

David Rich
Verification Technologist
Design Verification & Test Division
Mentor Graphics Corporation
dave_rich@mentor.com
Office:   408 487-7206
Cell:     510 589-2625

 


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