Subject: Re: too many functions?
From: Rob Anderson (rob@reawebtech.com)
Date: Thu Dec 12 2002 - 18:36:16 PST
Comments below:
David Bishop wrote:
> Rob Anderson wrote:
>
>>John Wrote:
>>
>> > >If there is a logic-state meaning, 1164 should
>> > > add the function; if there is a computational
>> > > meaning, numeric-std.
>>
>>Then David B. wrote:
>>
>> >
>> > Agreed. Unfortunately this got overlooked when 1164 was originally
>> > published.
>> >
>> > The new "match" functions in 1076.3 (numeric_std) would only
>> > be for the "signed" and "unsigned" types.
>>
>>This question is not answered:
>>
>>"match" does not have a computational meaning, so why
>>are we adding it to numeric_std?
>>
>
> "match" for the "signed" and "unsigned" types have to be in the
> numeric_std package because that is where the "signed" and
> "unsigned" types are defined. You can't put there anywhere
> else unless you create yet another package.
Clear, but beside the point.
>
> For completeness, if you can match a "std_logic_vector" should
> you not be able to match an "unsigned"?
Illogical. The fact "it" is in 1164 does not imply "it"
should be in numeric_std.
There are lots of functions in 1164 that are not in numeric_std.
"not be able to match an "unsigned"?
UGH! I don't think you should be able to "XOR" two real numbers
either. VHDL has types to protect against bad code.
>
> Yes, you will have to do a "to_x01" on it before you can actually
> perform any numeric fuctions on it.
>
You mean to_01. to_x01 isn't in this package either. To_01 was added
to account for default behavior of all metavalues in these types.
A metavalue in any location causes the whole array to be set to one
value. The reasoning was that it was incorrect to handle individual
bit positions for these types.
>
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