Re: Query related to escaped character in verilog

From: Steven Sharp (sharp@cadence.com)
Date: Wed Feb 09 2005 - 16:22:00 PST

  • Next message: Neil Korpusik: "Re: Query related to escaped character in verilog"

    >Attached is a uuencoded tar-file with escape-test-code and the outputs from
    >VCS 7.2 and ModelSim 6.0
    >
    >Hopefully the uuencoding will preserve all the interesting characters.

    My uudecode won't decode something containing a NUL character, so I
    can't read your file.

    >The octal-13 character was also different (line feed or ^M), as were a few
    >other of the obscure-variety characters.

    Were you on a PC? This might be a classic carriage-return/linefeed
    versus linefeed issue.

    >I don't know if I agree that we should match Verilog-XL if we think it is
    >doing something wrong. Seems like we cleaned up a couple of Verilog-XL-isms
    >for IEEE Verilog-1995 and if we think printing a space when a
    >null-character was requested is wrong, I am inclined to say so.

    And do you have any real argument that this is wrong?

    Note that NUL characters tend to mess up any application written in C.
    And if you tried to specify that NUL characters be printed out,
    simulators with I/O libraries written in C might start truncating
    outputs in a variety of unexpected ways. Have you ever tried printing
    out NUL characters using %c in the middle of a complex format? NC can
    do it, but I don't think most other simulators can.

    > I have not
    >tried this with C yet. Any takers?

    You can't print out an embedded NUL with %s in C, because a NUL will
    terminate the string.

    >I must admit that I would never base a Verilog-simulator-buying decision on
    >this, but we should probably clean it up.

    The current specification in the LRM is lacking, and should be clarified.
    This assumes that we can agree on what to specify. What XL does makes
    reasonable sense, and is the de facto standard. I don't see a reason to
    specify anything else.

    Steven Sharp
    sharp@cadence.com

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