[sv-cc] Errata? Handling DPI parameters of type 'reg'

Several early DPI users have wanted to pass 'reg' scalars or vectors
across
the DPI boundary.

However, the LRM DPI sections only mention 'logic' scalars and packed
arrays as
legal 4-state entities for the DPI interface (E.6.4 table and E.6.7).

I am told that the group did intend to include 'reg' items. In
addition, Dave Rich
of SV-BC states that he knows no semantic difference between 'logic' and
'reg'
as the language now stands.

If you do not believe that the 'reg' data type should be essentially
treated as
being interchangeable with 'logic', please make this known.

However, if there is a group consensus that we should accept reg
parameters as
equivalent to logic parameters, I propose to make this explicit:
otherwise the reader
must extrapolate our intent or consult type equivalence material
separated from the
DPI section by hundreds of pages.

Three changes might suffice for this:

1. E.6.4 table of SV/C type equivalences: replace "logic" with
"logic/reg".

2. E.6.4 table footnote.
   The footnote is "Encodings for bit and logic are given in file
svdpi.h. Refer to Annex E.9.1.1."
   (Section E.9.1.1 only discusses scalar encodings).
   I propose adding the following sentence:
   "Reg parameters can use the same encodings as logic parameters."

3. E.6.7: Sentence preceding Encoding table:

   Before: "Table E-2 defines the encoding used for a packed logic array
represented as svLogicVec32."
   After: "Table E-2 defines the encoding used for a packed logic or
reg array represented as svLogicVec32."

Please let me know your opinions on handling the reg type, and on any
LRM changes that
you believe should or should not be made to support this.

Thanks for considering this,
Ralph
Received on Tue Jul 27 13:21:58 2004