the list was in the cc list .. forgot to reply to all Jonathan David j.david@ieee.org jb_david@yahoo.com http://ieee-jbdavid.blogspot.com Mobile 408 390 2425 ----- Forwarded Message ---- From: Jonathan David <jb_david@yahoo.com> To: David Miller <David.L.Miller@freescale.com>; Nourdine Belhous <nourdine_belhous@mentor.com> Cc: Verilog-AMS LRM Committee <verilog-ams@eda.org> Sent: Thursday, June 5, 2008 12:19:57 PM Subject: Re: more Clause 3 comments the one I use every day (the product of a former employer of mine) leaves the wire to z but the reg to x .. makes sense to me.. if the net has no drivers - the value is undriven (z) if the net has a driver (ie a reg) but its value is not known.. its value should be unk (ie x) 1. we should carefully look at what 1364-2005 has to say about this.. and check to see if the simulator that is NOT following the standard as written has a switch to enable the conforming option.. (or if your environment setup in the other one has some pli or something that turns all z to x.. - or a command line option) See 1364-2005 4.2.1 the one that has the net at X is NOT conforming to the (latest) verilog standard.. at least as setup on your site.. jbd Jonathan David j.david@ieee.org jb_david@yahoo.com http://ieee-jbdavid.blogspot.com Mobile 408 390 2425 ----- Original Message ---- From: David Miller <David.L.Miller@freescale.com> To: Nourdine Belhous <nourdine_belhous@mentor.com> Cc: Verilog-AMS LRM Committee <verilog-ams@eda.org> Sent: Wednesday, June 4, 2008 9:28:40 AM Subject: Re: more Clause 3 comments Hi Nourdine, Thanks, I changed my example to be 'wire mywire' instead. Unfortunately, when I tried this with two different commercial digital simulators, one gives mywire = x the other mywire = z So even the pure digital simulators don't seem to agree. Cheers... Dave Nourdine Belhous wrote: > Hi, > If you want to test the initial value of a net, you should declare a > wire (or anything specified as a net in the digital LRM) instead of a > register. > And you'll probably get a value of 'z' from the simulator. > > Nourdine BELHOUS. > > David Miller wrote: >> >>> >>> 3.7: "Unlike other digital nets which have an initial value of ‘x’,..." >>> Digitial nets have an initial value of z, not x. >>> >> >> I am confused. >> If I have: >> >> module test; >> reg myreg; >> initial $display("myreg = %b",myreg); >> endmodule >> >> Digital simulators print: >> myreg = x >> >> How is this value different from the initial value of myreg? >> >> >> Dave >> >> >> > > -- ============================================== -- its another day for you and me in paradise -- -- David Miller -- Design Technology (Austin) -- Freescale Semiconductor -- Ph : 512 996-7377 Fax: x7755 ============================================== -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.Received on Thu Jun 5 14:09:13 2008
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