David,
>> PROPOSAL 4
>>
>> Define mixed signed/unsigned logic. Add "+", "*", "-", and "/" operators
>> for all combinations of UFIXED/SFIXED. This is another fairly common
>> operation in signal processing hardware that is well-defined. David
>> noted
>> that bit literals need a type cast anyway, so we shouldn't have the same
>> problem as mixed arithmetic in numeric_std.
>
>
> The questions raised around this one have to do with bit litterals. Since
> you can't do a bit literal with an open ended type, this is not an issue.
> Once again, unless there is an objection this is Approved.
Consider this an objection.
I think the methodology here needs to be discussed and voted
upon here. In that discussion I would include all mixed
functions, such as: Y_ufixed <= A_ufixed + B_unsigned ;
On one hand, by providing the overloading makes the above
happen automatically, so the following would be legal:
Y_ufixed <= A_ufixed + B_unsigned ;
On the otherhand, if we don't provide the overloading, we
would need to write something like the following:
Y_ufixed <= A_ufixed + to_ufixed(B_unsigned) ;
I for one like the additional notation when moving
between types. Although requiring this makes it harder
on the coder, it certainly makes the code easier to
review.
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 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Received on Wed Jul 7 07:32:18 2004
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