(r2) MapSubprogramGenericOnCall < P1076/Ballots

P1076/Ballots Web>Vhdl2019CollectedRequirements>MapSubprogramGenericOnCall (revision 2) (raw view)~~EditAttach~~

---+ Map Subprogram Generics on call

%TOC%

---++ Proposal Editing Information
   * Who Updates: OPEN, Main.JimLewis
   * Date Proposed: 2012-08-17
   * Date Last Updated: 2012-08-17
   * Priority:
   * Complexity:
   * Focus: Testbench
---++ Summary

Generics on a subprogram require a subprogram instance before usage. For some subprograms that are called only infrequently this is inconvenient.

Suggested during [[2012_MeetingJuly19]]
---++ Related and/or Competing Issues: Yes

Anonymous types on subprograms - this could be an alternative to it.
---++ Proposal Details

Declaration:

<verbatim>function Mux4
    generic ( type DataType ) 
    parameter (
      MuxSel :   in std_logic_vector(1 downto 0) ; 
      A, B, C, D :  in DataType
   ) return DataType is 
   . . . 
   end procedure Mux4; </verbatim>

Usage of the function:

<verbatim>Mux4 generic map (integer) (MuxSel, D1, D2, D3, D4) ; </verbatim>

---++ Questions

---++ General Comments

[[Main.BrentHahoe][&lt;Brent Hayhoe&gt;]] 2014-03-27 - I think that this is a good idea, just slightly concerned that the usage syntax might seem a bit messy. Perhaps this might be a little clearer:

<verbatim>generic map (integer) Mux4 (MuxSel, D1, D2, D3, D4) ; </verbatim>

It seems slightly more like a normal function call (to me). [[Main.BrentHahoe][&lt;/Brent Hayhoe&gt;]]

Main.LievenLemiengre - 2016-03-11 - It is tricky to make this work with the type checker & overload resolution but it can be done. I don't like 'generic map' in expressions so I suggest you drop it completely.
<verbatim>
  result := Mux4(integer)(MuxSel, D1, D2, D3, D4);
  result := Mux4(bit_vector)(MuxSel, D1, D2, D3, D4)(1); -- mux4, specialized for bit_vector, invoke it, take an element out of the array
  result := Mux4(integer)(MuxSelA, D1, D2, D3, D4) + Mux4(integer)(MuxSelB, D1, D2, D3, D4)</verbatim>
---++ Supporters

-- [[Main.BrentHahoe][Brent Hayhoe]] - 2014-03-27

-- Main.JimLewis - 2014-12-03

_Add your signature here to indicate your support for the proposal_

Topic revision: r1 - 2020-02-17 - 15:34:56 - TWikiGuest

P1076/Ballots