Re: errata/318: Table 30, 9.3.2, procedural assign to nonconstant part select and force of nonconstant bit-select

From: Shalom.Bresticker@motorola.com
Date: Wed Apr 02 2003 - 00:10:02 PST

  • Next message: Shalom.Bresticker@motorola.com: "errata/319: constant array element select as LHS of continuous assignment"

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    The following reply was made to PR errata/318; it has been noted by GNATS.

    From: Shalom.Bresticker@motorola.com
    To: Brad Pierce <Brad.Pierce@synopsys.com>
    Cc: etf-bugs@boyd.com
    Subject: Re: errata/318: Table 30, 9.3.2, procedural assign to nonconstant
     part select and force of nonconstant bit-select
    Date: Wed, 2 Apr 2003 11:04:06 +0300 (IDT)

    > In Table 30, why can the left-hand side of a procedural
    > assignment use a nonconstant bit-select or a nonconstant
    > indexed part-select, but only a constant part-select?
    >
    > In 9.3.2 why can the left-hand side of a force be a nonconstant
    > part-select, but only a constant bit-select?
     
     Dennis has the right idea, but I don't completely agree.
     
     4.2.1, para. 2, says, "There are two types of part-selects, a constant
     part-select and an indexed part-select."
     
     A "constant part-select" has the form vect[msb:lsb].
     
     An "indexed part-select" has the form vect[base +: width] or
     vect[base -: width]. "width" is always constant. "base" may be constant or not.
     If "base" is constant, then it is a "constant indexed part-select".
     
     So Table 30 is precise: The LHS of a procedural assignment may be a "constant
     part-select". It may also be an "indexed part-select", constant or not.
     
     On the other hand, the LHS of a continuous assignment may be a "constant
     part-select" or a "constant indexed part-select".
     
     
     Re 9.3.2 and "force": There the term "part-select" remains from 1364-1995, where
     there was only one type of part-select. Presumably it should be like the LHS of
     a continuous assignment (both are "net_lvalue"). So probably "part_select of a
     vector net" should be changed to "constant part-select or constant indexed
     part-select of a vector net".
     
     Also, in accordance with a previous issue, I think #75, "concatenation" should
     maybe be "concatenation or nested concatenation".
     
     And the same changes should probably be made in 12.3.2 in the list following
     para. 1, where it says, "The port reference ... can be ...".
     
     Also see related issue #198.
     
     

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