Re: enhancement/547: define size zero replication constant

From: Shalom.Bresticker@freescale.com
Date: Sat May 29 2004 - 22:10:00 PDT

  • Next message: Shalom Bresticker: "Re: enhancement/580: Add some system functions for use in constant expressions"

    The following reply was made to PR enhancement/547; it has been noted by GNATS.

    From: Shalom.Bresticker@freescale.com
    To: btf-bugs@boyd.com
    Cc:
    Subject: Re: enhancement/547: define size zero replication constant
    Date: Sun, 30 May 2004 08:24:43 +0300 (IDT)

     An independent development of the same enhancement:
     
     ---------- Forwarded message ----------
     Date: 28 May 2004 23:03:05 GMT
     From: Steve Meyer <sjmeyer@www.tdl.com>
     Reply-To: sjmeyer@pragmatic-c.com
     Newsgroups: comp.lang.verilog
     Subject: Re: Repeat concatenation and Modelsim
     
       GPL Cver allows 0 width concats because a user we were not matching XL.
     The algorithm is that a 0 repeat count removes the element. It is then
     an error if the entire concatenate disappers (i.e. becomes zero width).
     Here is the bug report test:
       
     ============
     
     module top;
        reg [10:0] rf_addr_ext;
        reg [10:0] rf_addr;
        parameter AW = 5;
        parameter DW = 5;
     initial begin
             rf_addr_ext = {{AW - DW{1'b0}}, rf_addr};
     end
     
     endmodule
     
     ============
     
     On Tue, 25 May 2004 16:18:38 +0100, DW <dave_wooff@hotmail.com> wrote:
    > Hello,
    > Can anyone confirm that the Verilog language definition rules out a repeat
    > concatenation of 0. i.e.
    > {0{1'b1}} is NOT allowed.
    >
    > Modelsim Altera v5.7e seems to let this pass and produces invalid code.
    > Quartus II version 3.0 seems to reject the use of this, although I have been
    > informed that a later release (version 4.0 I believe) allows it (when it
    > apparently should not).
    >
    > Although the example given is simplistic, I had used a combination of
    > defparam'd parameters which produced the 0 repeat. I do not have a complete
    > language reference (could be a good investment).
     
     
     

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