VHDL Issue Number:      0230
Classification:         Language Definition Problem
Language Version:       VHDL-87
Summary:                Unclear definition of driving value of composite
                        resolved signal.
Related Issues:
Relevant LRM Sections:  12.6.1
Key Words and Phrases:
Current Status:         Submitted
1076-1993 Disposition:  Closed (All Issues Completely Addressed)
Disposition Rationale:  
Superseded By:          N/A
-----------------------
Date Submitted:         1991/03/21
Author of Submission:   Clive Charlwood
Author's Affiliation:   Synopsys Inc.
Author's Post Address:  1098 Alta Ave.
                        Mountain View, CA 94043
Author's Phone Number:  (415) 962-5425
Author's Fax Number:    
Author's Net Address:   crc@synopsys.com
-----------------------
Date Analyzed:          TBD
Author of Analysis:     TBD
Revision Number:        $Revision: 1.9 $
Date Last Revised:      $Date: 1995/05/13 19:34:42 $


Description of Problem
----------------------
(This was Endot VHDL LRM Trouble Report #JM11           7/25/88)

By the interpretation of the term "resolved signal" given in JM10, there can be
composite resolved signals whose scalar subelements are not resolved.  The
definition of the driving value given in 12.6.1 of the LRM does not cover this
case (rather, it covers it in a way which is obviously wrong).


Proposed Resolution
-------------------
We proceed as if the following language were in the LRM:

        For a composite resolved signal R, the driving value of R is the result
        obtained by executing the resolution function associated with R, where
        that function is called with an input parameter consisting of the
        concatenation of the "aggregate sources" of R.  Each "aggregate source"
        is an aggregate of the driving values of the scalar subelements of R
        from the same process or port.  However, if any of the subelement
        drivers of an aggregate source is determined by a null transaction,
        then the entire aggregate source is excluded as one of the elements of
        the array which is the input parameter of the resolution function.


VASG-ISAC Analysis & Rationale
------------------------------
TBD


VASG-ISAC Recommendation for IEEE Std 1076-1987
-----------------------------------------------
TBD


VASG-ISAC Recommendation for Future Revisions
---------------------------------------------
TBD