RE: [sv-bc] RE: Clarification for `1 usage in unpacked array concatenation

It appears to me that Daniel is correct that the LRM is ambiguous about this.

From: owner-sv-bc@eda.org [mailto:owner-sv-bc@eda.org] On Behalf Of Daniel Mlynek
Sent: Thursday, July 24, 2014 10:08
To: Rich, Dave
Cc: Goel, Rohit (Noida MED RTLC Synthesis); sv-bc@eda.org
Subject: Re: [sv-bc] RE: Clarification for `1 usage in unpacked array concatenation

I'm not sure if Dave's interpretation comes from explicit LRM rule.
LRM for says only that UAC: elements shall be interpreted as : "An item whose self-determined type is assignmentcompatible with the element type of the target array shall represent a single element" but does not say how assignment should be performed. IMHO each element assignment should be done according to general SV  rules so A[0] would be 4'b1111 according to Dave interpretation special assignment  similar to vector concatenation should be done.
Maybe I'm missing something but imho this case is in grey/undefined area of LRM. I think that rule cited above was added to define cases where element by element assignment are possible vs cases other cases possible in UAC, not to define assignment rules

DANiel
W dniu 7/23/2014 4:25 PM, Rich, Dave pisze:
The operands in an unpacked array concatenation are self-determined, just like Verilog integral concatenation. So 1'b1 should be the result. Assignment patterns are context determined. This is one of the key distinctions between the two forms.

Dave


From: owner-sv-bc@eda.org<mailto:owner-sv-bc@eda.org> [mailto:owner-sv-bc@eda.org] On Behalf Of Goel, Rohit (Noida MED RTLC Synthesis)
Sent: Wednesday, July 23, 2014 3:49 AM
To: sv-bc@eda.org<mailto:sv-bc@eda.org>
Subject: [sv-bc] Clarification for `1 usage in unpacked array concatenation

In SV 1800-2009 concatenations could be used as source expressions for unpacked arrays (section 10.10). I have a query regarding usage of `1 in unpacked array concatenation. If the RTL has something like below

logic [3:0] A [0:0];
initial
begin
               A = {'1};
end

Does this mean that the value of A[0] after assignment will be "1111" or will it be "0001"?

Thanks & Regards
Rohit Goel

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