RE: MOVEA -> EVAL

[Joel Fritz <JFritz@xxxxxxxxxxxxxxxx>]

Kind depends on how you define "best."  I'll admit it, I've never used movea
much, because I didn't bother to study the documentation.  I've used loops a
lot.  

Seems like anything that uses pointers to shuffle stuff around and/or does
storage mapping needs to be hidden inside a procedure to spare those who
come after from needing to think about the details.  That also means it has
to work correctly. I think that's what's attractive about movea.

> -----Original Message-----
> From: bmorris@ca.ibm.com [mailto:bmorris@ca.ibm.com]
> Sent: Wednesday, June 06, 2001 9:53 AM
> To: RPG400-L@midrange.com
> Subject: Re: MOVEA -> EVAL
> 
> 
> 
> >Date: Tue, 5 Jun 2001 17:34:22 -0400
> >From: "Charlie Massoglia" <cmassoglia@voyager.net>
> >
> >Wouldn't the following be much easier to understand than 
> using pointers
> and
> >still far more efficient than a MOVEA?
> >
> >d                          ds
> >d  xarr1                                100     dim(10)
> >d     arr1                                         overlay(xarr1)
> >d                          ds
> >d  xarr2                                  10     dim(100)
> >d     arr2                                         overlay(xarr2)
> >
> >c                       eval        
> %subst(xarr2:1:%size(xarr1)) = xarr1
> >c                       eval        xarr2 = xarr1
> 
> Charlie, if you intended the dim(10) to be on the arr fields 
> rather than
> the xarr fields, then yes, that would work, and may be easier to
> understand.
> But your code doesn't handle the array starting indexes.
>        C        MOVEA      arr1(n)     arr2(m)
> 
> It's probably not _any_ more efficient than MOVEA.  MOVEA just sets
> pointers,
> calculates lengths, and copies in one fell swoop.  (None of 
> this applies
> to MOVEA with numeric arrays - the compiler uses a loop for those, to
> handle
> conversions; you'd have to use a loop too (or possibly just 
> EVAL directly,
> depending on the number of elements and starting indexes.)
> 
> But, I'm still waiting for someone to post an example where 
> using MOVEA is
> the best solution :)
> 
> Barbara Morris
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