Re: errata/454: 2.3.1: 2'sb0000000_10 == 2'sb10 ?

From: Shalom Bresticker (Shalom.Bresticker@motorola.com)
Date: Sun Aug 31 2003 - 02:00:01 PDT

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    The following reply was made to PR errata/454; it has been noted by GNATS.

    From: Shalom Bresticker <Shalom.Bresticker@motorola.com>
    To: Steven Sharp <sharp@cadence.com>
    Cc: etf-bugs@boyd.com
    Subject: Re: errata/454: 2.3.1: 2'sb0000000_10 == 2'sb10 ?
    Date: Sun, 31 Aug 2003 11:49:09 +0300

     Actually, by IEEE standard rules, anything not forbidden is permitted.
     (That's not exactly what the rules say, but that's approximately the meaning.)
     
     So a tool should not produce an error.
     
     Especially because it is explicitly permitted that the unsigned number be
     smaller than the size constant.
     
     Shalom
     
     
    > >In a numerical constant, if the unsigned number is larger than
    > >the size specified for the constant, is the unsized number
    > >truncated, losing the bits on the left?
    >
    > Well, the size of the resulting constant definitely has to be the size
    > that was specified. That much is clear in the LRM. How the value of
    > those bits are determined in this situation is not clear. Truncation
    > would be consistent with all other related situations in the language.
    >
    > I would expect a tool to at least provide a warning in this situation.
    > It would not be unreasonable to consider this to be illegal syntax and
    > produce an error. However, Verilog-XL just produces a warning and
    > truncates. The result is as you suggested.
     
     --
     Shalom Bresticker Shalom.Bresticker@motorola.com
     Design & Reuse Methodology Tel: +972 9 9522268
     Motorola Semiconductor Israel, Ltd. Fax: +972 9 9522890
     POB 2208, Herzlia 46120, ISRAEL Cell: +972 50 441478
     
     
     

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