Re: Alternative to MOVEA?

[Jeff Crosby <jlcrosby@xxxxxxxxxxxxxxxx>]

boldt@ca.ibm.com wrote:

> Mike wrote:
> >I'm trying to join the twentieth century here and replace all my MOVEs
> >with EVALs, but this one has me stuck. If I have a 9-element array  RA and
> >I want to fill the last three elements with, say, "X", I can code:
> >
> >MOVEA          *ALL('X')           RA(7)
> >
> >Is there a way I can do the same thing  using EVAL?
>
> Barbara wrote:
> >Here's another way that will probably perform somewhat better,
> >if the number of elements is very large (which it's not in
> >your case):
> >
> >D data      s             65535a    based(pData)
> >D pData     s                  *
> >C           eval    pData = %addr(RA(7))
> >C           eval    numElems = %elem(RA) - 7 + 1
> >C           eval    %subst(data : 1 : %size(RA) * numElems)
> >C                       = *ALL'X'

I don't like MOVEA for clearing specific hardcoded elements of an array,
but, forgive me Barbara, I would much rather use MOVEA than the above
because MOVEA is clearer as to what is happening.

> If you always know that you just want to set the last three
> array elements, I'd probably just code it as:
>
>      RA(%elem(RA)-2) = *all'X';
>      RA(%elem(RA)-1) = *all'X';
>      RA(%elem(RA)  ) = *all'X';
>
> Anyways, personally, I don't think this qualifies as a
> "reasonable" use of MOVEA.  For most "normal" situations,
> the FOR loop is a good alternative.

FWIW, when I look at old code and see a MOVEA clearing some number of
elements of an array where  the element is hardcoded, I immediately feel
I have a design issue.

--
-Jeff

New email address: jlcrosby@dilgardfoods.com

The opinions expressed are my own and not necessarily
the opinion of my company.  Unless I say so.