errata/522: A.2.2.3: delay2 and delay3 should be constant expressions

From: Shalom Bresticker (Shalom.Bresticker@motorola.com)
Date: Mon Jan 05 2004 - 08:20:00 PST

  • Next message: Steven Sharp: "errata/522: Re: errata/522: A.2.2.3: delay2 and delay3 should be constant expressions"

    >Number: 522
    >Category: errata
    >Originator: Shalom Bresticker <Shalom.Bresticker@motorola.com>
    >Description:

    7.14.1 says,

    "The syntax for delays on gate primitives (including user-defined primitives;
    see Clause 8), nets, and continuous assignments shall allow three values each
    for the rising, falling, and turn-off delays. The minimum, typical, and maximum
    values for each delay shall be specified as constant expressions separated by
    colons. There shall be no required relation (e.g., min <= typ <= max) between
    the expressions for minimum, typical, and maximum delays. These can be any three
    constant expressions."

    In the BNF, these delays are expressed as "delay2" and "delay3".

    After the changes of issue 174, they now appear as (see A.2.2.3):

    delay3 ::=
              # delay_value
            | # ( mintypmax_expression [ , mintypmax_expression [ ,
    mintypmax_expression ] ] )
    delay2 ::=
              # delay_value
            | # ( mintypmax_expression [ , mintypmax_expression ] )
    delay_value ::=
              unsigned_number
            | real_number
            | identifier

    These do not express that delay2 and delay3 should be constant expressions,
    which generally is expressed in the grammar wherever possible.

    delay_value cannot be changed because it is used elsewhere in non-constant
    contexts.

    I propose to add

    constant_delay_value ::=
        unsigned_number
    | real_number
    | parameter_identifier
    | specparam_identifier
    | genvar_identifier

    and change delay_value in delay2 and delay3 to constant_delay_value.

    I would have liked to change mintypmax_expression to
    constant_mintypmax_expresssion,
    but I see that Verilog-XL accepts hierarchical parameter references in delay2
    and delay3,
    which are not allowed in constant_mintypmax_expression. 

    --
Shalom Bresticker                           Shalom.Bresticker@motorola.com
Design & 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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