RE: [sv-bc] reg vs. logic

No, the 'reg' output of a UDP is not the same as a variable of type reg
or logic. You can't procedurally assign to or read a UDP reg, and
furthermore, it cannot represent the 'z' state. It is a classic example
of keyword reuse.

And yes, there remains only one fundamental difference between the 'reg'
data type and the 'logic' data type: they have different sets of letters
to spell them.

Dave


> -----Original Message-----
> From: Michael (Mac) McNamara [mailto:mcnamara@cadence.com]
> Sent: Monday, March 06, 2006 9:58 AM
> To: Rich, Dave; Bresticker, Shalom; sv-bc@eda.org
> Subject: RE: [sv-bc] reg vs. logic
> 
> Isn't this just the ancient sequential UDP syntax, which holds the
> previous value of the output in a 1364 reg, so that the new value can
be
> specified in the table as a function of the inputs, and the registered
> current output?
> 
> I do not view this as an arbitrary reuse of a keyword.  This reg has
all
> of the same behavior of any other declaration of a module with a
> registered output.  It would have been less useful if different syntax
> were used.
> 
> As both output reg declarations are the same, then because elsewhere
we
> say that "reg" and "logic" are synonyms, then logically it should
follow
> that one should be able to use "logic" here.
> 
> ( I will enclose my gripe about introducing multiple ways to specify
the
> same thing, while also using up a useful five letter word in
parenthesis).
> 
> 
>  -----Original Message-----
> From: 	Rich, Dave [mailto:Dave_Rich@mentor.com]
> Sent:	Mon Mar 06 08:23:47 2006
> To:	Bresticker, Shalom; sv-bc@eda.org
> Subject:	RE: [sv-bc] reg vs. logic
> 
> One could argue that the 'reg' keyword is being re-used here and is
not
> the same a 'reg' variable.
> 
> 
> 
> ________________________________
> 
> From: owner-sv-bc@eda.org [mailto:owner-sv-bc@eda.org] On Behalf Of
> Bresticker, Shalom
> Sent: Monday, March 06, 2006 6:58 AM
> To: sv-bc@eda.org
> Subject: [sv-bc] reg vs. logic
> 
> 
> 
> A.5.2 shows the following BNFs:
> 
> 
> 
> udp_output_declaration ::=
> 
>       { attribute_instance } output port_identifier
> 
>     | { attribute_instance } output reg port_identifier [ =
> constant_expression ]
> 
> 
> 
> udp_reg_declaration ::= { attribute_instance } reg variable_identifier
> 
> 
> 
> 
> 
> Are these exceptions to the rules that reg and logic are the same, or
> oversights in the BNF?
> 
> 
> 
> Shalom
> 
> 
> 
> 
> 
> Shalom Bresticker
> 
> Intel Jerusalem LAD DA
> 
> +972 2 589-6852
> 
> +972 54 721-1033
> 
> I don't represent Intel
> 
>