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Guest

Wed Feb 02, 2005 7:46 pm   



I went and asked a Simvision person. Apparently there is
a license for Simvision. If you are running a simulation with
Simvision, it uses both a simulation license and a Simvision
license. However, you can run Simvision in this post-
processing environment mode to look at waveforms, and
then it only uses a Simvision license.

You can get additional Simvision licenses at lower cost
than a full simulation license. Apparently a single user
can also use a single Simvision license to open multiple
Simvision windows and look at the results of multiple
simulations at the same time.
This sounds like it may be what you are looking for.


Guest

Wed Feb 02, 2005 7:58 pm   



It certainly sounds reasonable that generating a smaller
binary file format should be faster than generating VCD.
I have heard that argument made before, and it always
sounds reasonable. However, I know that in the past,
actual measurements have shown that it is faster to dump
VCD than some binary formats. I don't know what the
reasons were, and perhaps things have changed.

Jason Zheng
Guest

Wed Feb 02, 2005 8:08 pm   



Ajeetha wrote:
Quote:
But isn't it true that generating VCD takes much longer than say SHM,
as it is a binary format and file size being small, file-IO is expected
to be faster? That's the reason why I recommended using SHM2VCD
conversion.

Anyway I learnt quite some useful stuff via this thread on this
LXT/GTKWave features - thanks!

Ajeetha

Ajeetha,


Do you know where to get shm2vcd? Is it supposed to come with ncverilog?

-jz

Jason Zheng
Guest

Wed Feb 02, 2005 8:53 pm   



bybell_at_rocketmail.com wrote:
Quote:
Jason Zheng wrote:
p.s. Does gtkwave have rising/falling edge finders like
signalscan/simvision? I looked and couldn't find any.


Yes. Highlight the signal in question then click on Search->Pattern
Search in the menu.

Then a popup will appear. Click the button on the left to, say,
"rising edge" then press "Mark" to lay down alternate gridlines or
"Fwd" or "Bkwd" to move the marker to the next edge/string/whatever.

Note that you can do this with multiple signals at once like an address
bus equals a value and valid is high on a rising clock edge, etc. Also
note that for strings you will have to press enter on the value. The
finder also works with timeshifted signals which is how you can do
searches that don't happen in zero time. (e.g., if you're watching
something move through pipe stages)


This is great! Much better than the single-signal edge finder on other
software.

Quote:
If you haven't already, copy .gtkwaverc to your home directory and the
viewer will look nicer than the black and white screens I've seen on
some people's screen grabs.


Under the root directory of the tarball. Maybe in the future put in /etc
by default?

Quote:
BTW, something not really documented that works nicely is to zoom full
then click the RMB, drag it left or right, and release. The area
between the two cursors defines the new left and right margins. A
couple of iterations of this is a quick way to zero in to a specific
part of a trace.


Neat trick! Thanks again!

-jz


Guest

Wed Feb 02, 2005 11:43 pm   



sharp_at_cadence.com wrote:
Quote:
It certainly sounds reasonable that generating a smaller
binary file format should be faster than generating VCD.
I have heard that argument made before, and it always
sounds reasonable. However, I know that in the past,
actual measurements have shown that it is faster to dump
VCD than some binary formats. I don't know what the
reasons were, and perhaps things have changed.

It depends on how computationally expensive it is to write out the
binary file. If there's little more to the file format than dumping
out values similar to VCD (a version of the old MTI .wav file format
comes to mind), the binary will probably be faster. Once you throw in
stuff like clock/counter detection, signal value reordering and
indexing, etc in order to increase the compression ratio, you'll take a
speed hit. Likewise goes with any compression layers (e.g., libz) on
top of the data: you don't achieve a 50-100:1 compression ratio on VCD
without doing a bit of work.

There's also the factor that since VCD is built into the simulator/PLI
and isn't some standalone generic library code, it doesn't really need
to burn memory on storing signal names, their sizes, previous value,
etc so when it dumps there's less page/TLB thrashing on large models.
If it's faster to split a simrun that performs a binary dump into
simulating with writing VCD then converting it offline with a separate
utility, memory access issues are probably the case.

-t

Ajeetha
Guest

Thu Feb 03, 2005 6:02 am   



I am not sure if they have such an executable sent out with NCSIM, but
you can do that via Simvision GUI. IIRC, You can actually do lot more
there - choose a time range, select few signals etc. I don't have NC
license currently to check.

Ajeetha
http://www.noveldv.com


Guest

Sat Feb 05, 2005 10:47 pm   



Dear Jason,

You can use the Undertow waveform viewer to view data from the
ncverilog simulator. The $shm_open uses a format that is proprietary to
Cadence. With Undertow you can use a a PLI or VPI routine that is
included in the Undertow distribution. This will compress your output
by up to 1300 times over a VCD file, particularly when the VCD file
sizes are getting very large. Typical results with the Veritools'
PLI/VPI are as follows;

15 million gate/RTL gate equivalent design:

On a 650 MHZ Solaris system

VCD file, 39 minutes with file size of 3.1 gigabytes

PLI/VPLI output file 5.1 minutes, file size of 2.5 megabytes

On a 3.2 GHZ Linux System;

PLI/VPLI output file 1 minute, 40 seconds, file size 2.5 megabytes

The waveform file from the Veritools' PLI/VPI has been designed to load
in and display signals in Undertow almost instantly regardless of how
big this file is.
You can down load the software at no cost from www.veritools.com. Send
a request as directed to get username and passwd for downloading the
software and for getting a no cost license.


Guest

Fri Mar 31, 2017 8:41 pm   



Hello
Does anyone can tell me how we can convert verilog code to VCD in Ncsim cadence.

Thanks

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