Geoffrey.Coram wrote: > Kevin - > Unfortunately, that x/z language is found in 1364-2005, clause > 4.8.2 (page 34 of the PDF). I don't think that means you can't change the behavior within an analog block, re-propose: Implicit conversion shall take place when an integer or logic expression is assigned to a real. Within an analog block if any bits of the expression are x or z then the real value becomes NaN (Not a Number), otherwise the bits are considered 0. It is illegal to assign NaN to a branch. Kev. > > I'm curious why 3.2.1 was taken out between VAMS drafts 2 and 3, > rather than 4.2.1.1 and 4.2.1.2. The 1364-2005 paragraphs > on conversion are in the Data types chapter. > > -Geoffrey > > > > Kevin Cameron wrote: >> >> http://www.eda-stds.org/verilog-ams/htmlpages/tc-docs/issues/0013/index.html >> >> >> I think converting x/z bits to 0 is a recipe for disaster, the old >> proposal was to produce a result of NaN (Not a Number) for the real >> which is handled efficiently by floating point hardware, and only >> only throw an error if NaN gets assigned to a branch. All reals >> without an initial assignment should probably be initialized to NaN >> rather than zero. >> >> Propose 4.2.1.2 becomes: >> >> Implicit conversion shall take place when an integer or logic >> expression is assigned to a real. If any bits of the expression are >> x or z then the real value becomes NaN (Not a Number). It is illegal >> to assign NaN to a branch. >> >> >> - and add NaN as a keyword. >> >> Kev. >> > -- True Circuits Inc. - http://www.truecircuits.com Tel: (650) 949 3400 Ext 3415 -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.Received on Fri Mar 28 11:34:56 2008
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