Proposal to allow parameter type declarations

From: Steve Meyer (sjmeyer@crl.com)
Date: Thu Mar 12 1998 - 10:13:15 PST


I propose changing parameter declaration statements to allow normal
reg range and signed declaration keywords. If feature has already been
proposed, just ignore this. Some examples (I am not sure if I am using latest
syntax):

 parameter signed [3:0] mux_selector = 0;
 paramater signed [0:3] mux_selector = 0; // only different if selects allowed
 parameter real r1 = 3.5e17;
 parameter p1 = 13'h7e;
 parameter [31:0] dec_const = 1'b1; // valued converted to 32 bits

Notes:
 1) For backward compatibility, parameter declarations without range or type
    allowed using current width determined by right hand side expression
    width still permitted.

 2) Parameters declared with ranges can possibly be stored more efficiently.
    Solves problem when constants are assigned initial (or # param
    or defparam) values using small decimal constants.

 3) Makes Verilog 98 compatibible with Verilog-AMS.

 4) I think selects from parameters should be explicitly allowed by standard
    following XL. In fact, every simulator needs to support selects from
    parameters or else models in Thomas-Moorby book will not run
    (i.e. dec_const[9] or dec_const[13:5]).
/Steve

-- 
Steve Meyer				Phone: (415) 296-7017
Pragmatic C Software Corp.		Fax:   (415) 296-0946
220 Montgomery St., Suite 925		email: sjmeyer@crl.com
San Francisco, CA 94104


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