VHDL Issue Number: 0213 Classification: Language Definition Problem Language Version: VHDL-87 Summary: Are interface declarations allowed at the root of a model? Related Issues: None. Relevant LRM Sections: 12.2.1, 12.2.3 Key Words and Phrases: Interface declarations, ports, generics, top-level design entity Current Status: Submitted 1076-1993 Disposition: Closed (All Issues Completely Addressed) Disposition Rationale: Section 12.1 was revised. Superseded By: N/A ----------------------- Date Submitted: 1991/03/20 Author of Submission: Paul Menchini Author's Affiliation: CAD Language Systems, Inc. Author's Post Address: P.O. Box 13036 Research Triangle Park, NC 27709-3036 Author's Phone Number: (919) 361-1913 Author's Fax Number: Author's Net Address: mench@clsi.com ----------------------- Date Analyzed: TBD Author of Analysis: TBD Revision Number: $Revision: 1.9 $ Date Last Revised: $Date: 1995/08/04 01:45:13 $ Description of Problem ---------------------- Can the root design entity of a design hierarchy have ports and generics? The LRM neither prohibits nor defines the meaning of this situation. Related to this issue is the absence of a paragraph analogous to the second paragraph of Section 12.2.1 in Section 12.2.3. Proposed Resolution ------------------- The root design entity of a design hierarchy should be allowed to have ports and generics; such ports and generics should be constrained. The values of such generics "come from outside the language"; if a generic has a default value such value may be used by "the outside" to supply a value to the generic. Similarly, the signals associated with formal ports (and any drivers of these signals) also "come from outside the language"; if a port has a default value such value may be used by "the outside" to supply an initial value to any drivers of the signal. VASG-ISAC Analysis & Rationale ------------------------------ TBD VASG-ISAC Recommendation for IEEE Std 1076-1987 ----------------------------------------------- TBD VASG-ISAC Recommendation for Future Revisions --------------------------------------------- TBD