Subject: Re: std_logic_1164: CP-010 and numeric_std:Rob_P1
From: Stephen Bailey (Stephen.Bailey@synopsys.com)
Date: Mon Dec 09 2002 - 11:10:20 PST
All,
To add my opinion to this discussion:
I agree with the view that the match function (should) work on
std_[u]logic[_vector], therefore, it should be defined in 1164. I see no
value in having identical subprograms in std_logic_1164 and numeric_std that
differ only by name (match vs. std_match). If anything, having different
names for identical routines creates confusion (although this is a
relatively minor consideration).
My recommendation for resolving this is:
1. Define the subprograms in std_logic_1164. Name them match. (No value
added for typing 4 additional characters plus it avoids potential homograph
with std_match alias below.)
2. Modify numeric_std to replace the now duplicate subprograms with aliases
to the subprograms in 1164. This will provide backward compatibility for
any code specifying "numeric_std.std_match". It also allows the numeric_std
package to be updated independent of 1164 (as long as 1164 is standardized
first or concurrently).
-Steve Bailey
> The problem with _moving_ the std_match functions from numeric_std to
> std_logic_1164 is that models that refer to numeric_std.std_match
> (either with selected names or via a use clause) would break.
>
> The problem with _copying_ the functions to std_logic_1164 is that you
> would then have homographs in the two packages, and models that use (in
> the use clause sense) both packages and refer to std_match would break.
>
> Hence my proposal to call the functions in std_logic_1164 match instead
> of std_match. You could add match as an alias for std_match in
> numeric_std if you want consistency of naming across the packages for
> new models.
>
> Cheers,
>
> PA
>
>
> On Sat, 2002-12-07 at 13:01, Jim Lewis wrote:
> > CP-010 Analyzed Add match functions like numeric_std.std_match
> > http://www.eda.org/vhdl-std-logic/proposals/CP-010-match-functions.txt
> >
> > In numeric_std, it was proposed in proposal Rob_P1/P2
> > (http://www.eda.org/vhdlsynth/pilot/hm/0026.html), that
> > the std_match functions for std_ulogic, std_logic_vector, and
> > std_ulogic_vector be moved to std_logic_1164.
> >
> > This would satisify CP-010 and Rob_P2. Is this a move that
> > everyone would support? Otherwise, CP-010 proposes adding a match
> > function to std_logic_1164. This means that we should add a
> > match function to numeric_std. There is more meaning to a
> > function when it is globally used.
> >
> > Cheers,
> > Jim
> >
> > --
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > Jim Lewis
> > Director of Training mailto:Jim@SynthWorks.com
> > SynthWorks Design Inc. http://www.SynthWorks.com
> > 1-503-590-4787
> >
> > Expert VHDL Training for Hardware Design and Verification
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> --
> Dr. Peter J. Ashenden peter@ashenden.com.au
> Ashenden Designs Pty. Ltd. www.ashenden.com.au
> PO Box 640 Ph: +61 8 8339 7532
> Stirling, SA 5152 Fax: +61 8 8339 2616
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>
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