Re: Query related to escaped character in verilog

From: Clifford E. Cummings (cliffc@sunburst-design.com)
Date: Wed Feb 09 2005 - 15:48:39 PST

  • Next message: Steven Sharp: "Re: Query related to escaped character in verilog"

    Hi, all -

    I am probably wasting my time looking at this but it was interesting.

    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.

    Doing a diff (Linux RedHat 7.3) between the tmpout.vcs and tmpout.mti
    actually showed a few differences (just a few and none of them are going to
    get me upset).

    I kind of thought that displaying a null character would not show anything
    (VCS did not print a " " but ModelSim did ad from this email thread it
    sounds like other simulators are doing the same).

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

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

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

    No need to send email to me directly. I am on the BTF email list (I was not
    sure if Neil was on the list or not).

    Regards - Cliff

    At 02:49 PM 2/9/2005, Steven Sharp wrote:

    > >module m;
    > >integer i;
    > >
    > >initial
    > >begin
    > >for (i=0;i<256;i=i+1)
    > >begin
    > > a = i;
    > > $display("s%sa", a);
    > >end
    > >end
    > >
    > >endmodule
    >
    >I assume you intended to declare "reg [7:0] a;" in there.
    >
    >
    > >What appears to happen is simply the obvious:
    > >
    > >the Verilog simulator just outputs the required byte (ASCII 0-255) into
    > >the data stream. What it looks like, how it is represented, how it
    > >behaves, that depends on how you view it or process it.
    >
    >
    >Well, except for ASCII 0, which gets converted into a space in the output.
    >
    >Steven Sharp
    >sharp@cadence.com

    ----------------------------------------------------
    Cliff Cummings - Sunburst Design, Inc.
    14314 SW Allen Blvd., PMB 501, Beaverton, OR 97005
    Phone: 503-641-8446 / FAX: 503-641-8486
    cliffc@sunburst-design.com / www.sunburst-design.com
    Expert Verilog, SystemVerilog, Synthesis and Verification Training


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