errata/225: The fourth port direction

From: Brad Pierce (Brad.Pierce@synopsys.com)
Date: Fri Dec 20 2002 - 19:28:45 PST

  • Next message: Shalom.Bresticker@motorola.com: "Re: errata/218: PROPOSAL - Nested attributes should be prohibited"

    Precedence: bulk

    >Number: 225
    >Category: errata
    >Originator: "Brad Pierce" <Brad.Pierce@synopsys.com>
    >Environment:
    >Description:

    Port directions are not declared directly, but are instead implied
    by the directions declared for port identifiers within port expressions.

    When the port expression is a concatenation and the port identifiers
    within it are declared with mixed directions, what is the direction of
    the port?

               module m (.p({a,b})) ;
               input a;
               output b;
               not(b,a);
               endmodule

    To me, it seems like either p is being declared here as an inout
    (no coercion involved) or this is an error. But I see only one place
    in the standard that speaks to this, namely, Table 139, which says
    there are actually four port directions --

               Input only
               Output only
               Bidirectional (input and output)
               A concatenation of input ports and output ports

    I think the fourth item is trying to talk about a concatenation of
    port expressions. If so, the function acc_fetch_direction() would
    probably not return "accInout" for port p, but instead would return
    "accMixedIo".

    (This issue is spun off from issue #54.)

    -- Brad

    This archive was generated by hypermail 2.1.4 : Fri Dec 20 2002 - 19:30:23 PST and
    sponsored by Boyd Technology, Inc.