[sv-bc] Re: [sv-ec] timeunit Declaration Verbosity

From: Clifford E. Cummings <cliffc_at_.....>
Date: Tue Oct 10 2006 - 12:13:04 PDT
Hi, All -

Heath first sent this to the EC but perhaps it would better reside in the BC(?)

Heath brings up what is also my primary objection to the new timeunit 
/ timeprecision pair of keywords.

Due to its convenience, I prefer and I recommend to students that the 
add a `timescale in front of every module that contains time delays 
(due to compile-order issues). The one nice feature for the new 
timeunit-timeprecision keywords is that when placed in a module, they 
are local to the module and turn off at the end of the module, 
allowing simulations to return to their regularly scheduled 
`timescale. For that reason, I recommend the new more verbose 
constructs to IP providers, so that their code will not change any 
other active `timescale in the user's design.

If I could combine the timeunit 1ns / 1ns; as Heath has recommended, 
then I would switch my allegiance and favor this new construct. I 
prefer the "/" separator just because it is like the `timescale 
separator but I could go with either option described by Heath.

Thoughts?

Regards - Cliff

At 04:20 PM 9/25/2006, Heath Chambers wrote:

>Was the verbosity of the new timeunit and timeprecision
>declarations brought up when they were first introduced?
>
>I'm used to putting `timescale in front of every module
>that I have that has a time delay inside; but if I want
>to follow that same convention using the new declarations,
>a significant amount of extra typing is required.
>
>How difficult would it be (from a vendor perspective and
>from a committee perspective) to allow something like
>the following one line shortcut:
>   timeunit time_literal [ / time_literal];
>   OR
>   timeunit time_literal [ , time_literal];
>
>The first time_literal would be the time unit and the
>optional second time_literal would be the time precision.
>The separator could either be the / like the `timescale
>directive or a comma, which ever the committee decided
>would be best.
>
>Example:
>   timeunit 1ns/10ps;
>   ==
>   timeunit 1ns;
>   timeprecision 10ps;
>
>Thanks,
>-- Heath
>
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----------------------------------------------------
Cliff Cummings - Sunburst Design, Inc.
14314 SW Allen Blvd., PMB 501, Beaverton, OR 97005
Phone: 503-641-8446 / FAX: 503-641-8486
cliffc@sunburst-design.com / www.sunburst-design.com
Expert Verilog, SystemVerilog, Synthesis and Verification Training
Received on Tue Oct 10 12:13:11 2006

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