VHDL Issue Number: 0240 Classification: Language Definition Problem Language Version: VHDL-87 Summary: Can a procedure parameter be disconnected? Related Issues: Relevant LRM Sections: 2.4, 4.3.3, 4.3.3.2, 8.3.1, Key Words and Phrases: bus, register, disconnection Current Status: Submitted 1076-1993 Disposition: Closed (All Issues Completely Addressed) Disposition Rationale: Section 2.1.1.2 Superseded By: N/A ----------------------- Date Submitted: 1991/03/22 Author of Submission: Chuck Swart Author's Affiliation: Mentor Graphics Corporation Author's Post Address: 8500 S.W. Creekside Place Beaverton, OR 97005-7191 Author's Phone Number: (503) 626-7000 Author's Fax Number: Author's Net Address: cswart@mentor.com ----------------------- Date Analyzed: TBD Author of Analysis: TBD Revision Number: $Revision: 1.7 $ Date Last Revised: $Date: 1995/05/13 19:34:42 $ Description of Problem ---------------------- Can a signal which is passed as a parameter to a procedure be disconnected within that procedure? There are two difficulties with this: 1. There is no mechanism to indicate that a signal parameter is a guarded signal. The syntax for interface signal declarations does allow the keyword BUS but it does not allow the keyword REGISTER. The use of BUS in this context was probably intended to apply only to ports. 2. Section 4.3.3.2 on association lists does not contain a requirement that if the formal has signal kind bus, that the actual must also have that kind. For port associations the actuals and formals need not have the same kind. Proposed Resolution ------------------- There are two reasonable solutions: 1. Disallow disconnection of subprogram parameters. 2. Allow disconnection of subprogram parameters. To do this one would have to change the syntax of interface declarations to allow guarded signals to be specified and require agreement of signal kinds for actuals which are associated with guarded formals in procedures. VASG-ISAC Analysis & Rationale ------------------------------ TBD VASG-ISAC Recommendation for IEEE Std 1076-1987 ----------------------------------------------- TBD VASG-ISAC Recommendation for Future Revisions --------------------------------------------- TBD