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# IFV and IUS, what's the difference?

Last post Wed, Jul 10 2013 3:59 AM by GAO SHIYANG. 7 replies.
 Started by archive 15 Apr 2007 07:26 PM. Topic has 7 replies and 2692 views
• #### Sun, Apr 15 2007 7:26 PM

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IFV and IUS, what's the difference?
 Hello Cadence,There are two similar simulation environment: IFV and IUS. Who know what's the difference with them? And one is another one's super set?Best regards,DavyOriginally posted in cdnusers.org by davyzhu
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• #### Mon, Apr 16 2007 1:48 AM

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RE: IFV and IUS, what's the difference?
 Hi Davy.Excellent question! :-)Here's the very high level answer (ask your AE for a demo of IFV too!).IUS is the Incisive Unified Simulator (unified because all the languages are supported natively in the same simulation kernel).IUS deals with dynamic simulation, i.e. time advances as you simulate and you can run behavioural testbench or modelling code.IFV is the Incisive Formal Verifier tool. Formal analysis involves building a mathematical model of your design, and then using formal proofs to see whether the design meets specific properties that you've written in PSL or SVA.In IFV there is no real notion of time - everything is done using mathematics and a "crank" which is like the clock of the registers.Although the two tools work differently under the hood, they both use the SimVision GUI as the front-end.This means that a designer who knows IUS feels instantly at home driving IFV. The same waveform window is used to show failing properties or to show coverage examples.Regards.Steve H.Originally posted in cdnusers.org by stephenh
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• #### Mon, Apr 16 2007 2:22 AM

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RE: IFV and IUS, what's the difference?
 Hi Steve,Excellent answer :)From your high level description, I infer that IUS and IFV are mutually-exclusive in the method the tool use. Right?But we know that IUS can also run SVA/PSL. So does IFV run faster? Or IFV have more intuitive methodology for us designer? If not, why we designers need IUS besides IFV?Any suggestions will be appreciated!DavyOriginally posted in cdnusers.org by davyzhu
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• #### Mon, Apr 16 2007 2:23 AM

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RE: IFV and IUS, what's the difference?
 Sorry, typo.If not, why we designers need IFV besides IUS?DavyOriginally posted in cdnusers.org by davyzhu
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RE: IFV and IUS, what's the difference?
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• #### Mon, Apr 16 2007 11:04 AM

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RE: IFV and IUS, what's the difference?
 As an early user of IFV (it used to be called ISV then, back in 2003 timeframe during our PSL book) I found it extremely useful. Assuming you add assertions anyway the flow was really simple as IUS itself:ncvlog -f flistncelab topisv top (Instead of ncsim top)It was incredibly seamless to use as a flow (though the tool in its beta/alpha stages had issues).And as Steph mentioned, the debug was another sweet spot - use SimVision, same as with NC.So it is almost like you can get rid of writing those throw away block level TBs. Please read our PSL/SVA book on FV chapter (www.abv-psl.org). We showed live/toy design of a traffic light controller and some interesting applications of this technology. HTHAjeetha, CVCwww.noveldv.comOriginally posted in cdnusers.org by ajeetha
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• #### Mon, Apr 16 2007 7:00 PM

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RE: IFV and IUS, what's the difference?
 Hello Ajeetha,Thanks a lot!You said "you can get rid of writing those throw away block level TBs". I hope it will do :)Best regards,DavyOriginally posted in cdnusers.org by davyzhu
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• #### Wed, Jul 10 2013 3:59 AM

Re: RE: IFV and IUS, what's the difference?
 HI Ajeetha,  I think the major benefit of IFV is that it can help designer to understand his assumption can be proven or not in an early developing phase.Also using IFV to do connection check or mux check is very efficient, we don't need to create testcase (Although IUS has assertion capability, we still need to create our own testcases, right? ) And also, the counter-example is very easy for us to understand what is wrong.Since I am new to IFV,  Is my understand here correct??
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