enhancement/400: reduce arithmetic operators x-pessimism

From: Shalom.Bresticker@motorola.com
Date: Fri Jul 25 2003 - 01:46:41 PDT

  • Next message: Shalom.Bresticker@motorola.com: "enhancement/401: reduce relational operators x-pessimism"

    Precedence: bulk

    >Number: 400
    >Category: enhancement
    >Originator: Shalom.Bresticker@motorola.com
    >Environment:
    >Description:

    Today, 4.1.5 says,
    "For the arithmetic operators, if any operand bit value is the unknown value x
    or the high-impedance value z, then the entire result value shall be x."

    There are cases where it is clearly possible to be less conservative.
    For example, if I add 5'b0000x + 5'b00000, then clearly the high-order bits
    have a definite value (0 in this case). 

    -- 
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

    This archive was generated by hypermail 2.1.4 : Fri Jul 25 2003 - 01:51:50 PDT and
    sponsored by Boyd Technology, Inc.