Re: MOVEA -> EVAL

["Peter Dow" <pcdow@xxxxxxxxx>]

Hi Barbara,

I ran across this piece of code today, and while I realize this isn't the
"best" solution, it was pretty common in pre-RPGLE days:

C                   MOVEA     '0000'        *IN(41)
Set indic.

In the days when a lot of indicators were required to do things with a
display file, this was a common technique to turn off a range of indicators.
It could also be used to both seton and setoff indicators within a range,
e.g.

C                   MOVEA     '01010101'    *IN(41)
Set indic.

which reduced two SETON/SETOF statements to a single line of source code.

Thought you might be interested.

Peter Dow
Dow Software Services, Inc.
909 425-0194 voice
909 425-0196 fax


----- Original Message -----
From: <bmorris@ca.ibm.com>
To: <RPG400-L@midrange.com>
Sent: Wednesday, June 06, 2001 9:52 AM
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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