errata/527: Re: errata/527: Replication operator on concats involving function calls

From: Shalom.Bresticker@motorola.com
Date: Thu Jan 08 2004 - 02:50:00 PST

  • Next message: Brad Pierce: "errata/527: Re: errata/527: Re: errata/527: Replication operator on concats involving function calls"

    The following reply was made to PR errata/527; it has been noted by GNATS.

    From: Shalom.Bresticker@motorola.com
    To: Brad Pierce <Brad.Pierce@synopsys.com>
    Cc: etf-bugs@boyd.com
    Subject: Re: errata/527: Replication operator on concats involving function
     calls
    Date: Thu, 8 Jan 2004 12:50:59 +0200 (IST)

     Brad,
     
     
    > In section (4.1.14) it says "If the replication operator is
    > used on a function call ...". But this is inconsistent with the
    > language of http://www.boyd.com/1364_btf/report/full_pr/73.html ,
    > because a replication operator cannot be used on a function
    > call, but only on a concatenation.
     
     Obviously, the text means a concatenation which contains a function call.
     If you want to change the language to say that explicitly, OK.
     
      
    > It seems to me that it should not be legal to implement
    >
    > result = {4(func(w)}
     
     Obviously, you mean {} instead of ().
     
    > as
    > result = { func(w), func(w), func(w), func(w) }
    >
    > and that if there's a side-effect in func, it should happen
    > exactly once. That is, the replication operator should
    > replicate the value of the concatentation. Otherwise, why can't
    > the result of the replication operator be used as an lvalue?
     
     Because it is not generally useful as an lvalue.
     And I think that has nothing to do with how it is evaluated on a RHS.
     
     
    > For example, shouldn't the following example unambiguously yield
    > |0001000100010001|, even though Verilog-XL didn't do it that way?
     
     Your "even though" is the answer to your question.
     That is a good enough reason.
     
     I have even been told, I seem to remember, that different simulators have treated {y,y} on LHS differently.
     
     Oh, and this duplicates issue 288, I think.
     
     Shalom
     
     
    >
    > module m (o);
    > output [15:0] o ;
    > reg [15:0] o ;
    > reg [3:0] t;
    >
    > function [3:0] f ;
    > input i ;
    > begin
    > t = t + i ;
    > f = t ;
    > end
    > endfunction
    >
    > initial begin
    > t = 0 ;
    > o = {4{f(1'b1)}} ;
    > $display("|%b|", o) ;
    > end
    >
    > endmodule
    >
    > Is replication an operator or syntactic sugar? If syntactic sugar,
    > why not allow it in lvalues?
     
     --
     Shalom Bresticker Shalom.Bresticker@motorola.com
     Design, Verification & 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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