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Old 05-26-2004, 12:05 PM
Pooja Maheshwari
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Default Enhanced VCD file!!

I want to generate enhanced VCD file as per IEEE1364-2001 standard.
I'm using ncverilog-5.1 version.

Std. says if filename is not given in "dumpports" task then it should be

dumped into "dumpports.vcd" file and identification codes for port
should be
"<n" where n is number starting from 0.

But ncverilog is dumping data into "verilog.evcd" file, and
identification codes are
also "#", "!" etc. I tried "+ncvcdextend", & "-dumpports_format 2"
switches also.

How can I get 2001 compliant evcd file with ncverilog?

Thanks in advance,
Pooja

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Old 05-26-2004, 09:35 PM
Steven Sharp
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Default Re: Enhanced VCD file!!

Pooja Maheshwari <[email protected]> wrote in message news:<[email protected]>...
> I want to generate enhanced VCD file as per IEEE1364-2001 standard.
> I'm using ncverilog-5.1 version.


Extended VCD existed before it was standardized. I believe there were
some changes in the standardized version, and NC has to support both.
This may account for some of the differences you are seeing.

> Std. says if filename is not given in "dumpports" task then it should be
> dumped into "dumpports.vcd" file and identification codes for port
> should be
> "<n" where n is number starting from 0.
>
> But ncverilog is dumping data into "verilog.evcd" file, and
> identification codes are
> also "#", "!" etc. I tried "+ncvcdextend", & "-dumpports_format 2"
> switches also.


The default filename difference is easy enough to deal with, or you can
specify a filename explicitly in the $dumpports call.

On the identification codes, the NC-Verilog documentation says:

By default, the signal identifier codes in an EVCD file differ from what
is specified in the IEEE standard. The IEEE standard specifies that the
identifier code is to be an integer preceded by <, which starts at zero
and ascends in one unit increments for each port. For example,
...
Cadence simulators use space-efficient identifiers in order to minimize
the size of the file. For example,
...
Use the -use_ieee_dumpport_ids command-line option when you invoke the
simulator if you want the identifier codes to conform to the IEEE standard.
If you are running the simulator in single-step invocation mode with the
ncverilog command, use the +use_ieee_dumpport_ids option.

I don't know why this is a separate option from the -dumpports_format
option, which controls some other file format changes. If you really
want IEEE format, you will want to use format 2, as you mentioned. It
is my understanding that the IEEE format is actually broken in the
standard, and does not behave in a desirable way.
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  #3 (permalink)  
Old 05-26-2004, 09:47 PM
Anthony J Bybell
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Default Re: Enhanced VCD file!!

Pooja Maheshwari <[email protected]> wrote in message news:<[email protected]>...

> But ncverilog is dumping data into "verilog.evcd" file, and
> identification codes are
> also "#", "!" etc. I tried "+ncvcdextend", & "-dumpports_format 2"
> switches also.
>
> How can I get 2001 compliant evcd file with ncverilog?


See if your other tools complain when trying to read it. If the files
read OK, it's probably no problem. From a VCD reader point of view,
those identifiers are merely symbolic, standards compliant or not.

For example, <number is a subset of all identifiers which are composed
of "#", "!", etc.

The strength/value identifiers however don't map so cleanly:

> static char *evcd="DUNZduLHXTlh01?FAaBbCcf";



-t
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