RE: [vhdl-200x-ft] Comment on FT22 re locally static array subtyp e

It is not clear whether this definition can be applied recursively to arrays
with unconstrained element types (FT-14). In other words, can I get a
locally static array subtype by applying a locally static index constraint
to the element type and array type?

type SIGNED_VECTOR is array (integer range <>) of SIGNED;
subtype SIGNED_4x3 is SIGNED_VECTOR(1 to 4).(2 downto 0);

Is SIGNED_4x3 a locally static subtype?

---
Ryan Hinton
L-3 Communications / Communication Systems - West
ryan.w.hinton@L-3com.com
-----Original Message-----
From: Peter Ashenden [mailto:peter@ashenden.com.au]
Sent: Monday, December 13, 2004 8:39 PM
To: vhdl-200x-ft@eda.org
Subject: [vhdl-200x-ft] Comment on FT22 re locally static array subtype
Folks,
In looking more closely at the wording in FT22, there appears to be an
issue.  The relevant part is:
  The line 606 in section 7.4.1 is changed from
  "A locally static array subtype is a constrained array subtype formed 
    by imposing on an unconstrained array type a locally static index 
    constraint"
  to
  "A locally static array subtype is a constrained array subtype formed 
   by imposing on an unconstrained array type with a locally static index 
   constraint. The unconstained array type must have a locally static
element
   subtype and locally static index subtype definitions."
First, there is no definition of a "locally static index subtype
definition".  However, that doesn't matter, since...
Second, a preceding sentence in that paragraph is
  A locally static index constraint is an index constraint for which each
  index subtype of the corresponding array type is locally static and in
  which each discrete range is locally static.
I think the intent of the proposed change was to specify that, not only must
the element subtype be locally static, but the index subtypes, specified by
the index subtype definitions, also be locally static.  That requirement is
already captured in the definition of a locally static index constraint, so
there is no need to respecify it.  The changed wording only need be
  "A locally static array subtype is a constrained array subtype formed 
   by imposing on an unconstrained array type with a locally static index 
   constraint. The unconstained array type must have a locally static
element
   subtype."
Comments?
Cheers,
PA
--
Dr. Peter J. Ashenden                        peter@ashenden.com.au
Ashenden Designs Pty. Ltd.                   www.ashenden.com.au
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