Re: MOVE and Z-ADD are **NOT**THE**SAME** (was Z-ADD or Eval?)

Ahhh, yes.  MOVEing 123.45 into a P 7,4 field that contains 999.9999 would 
result
in the field containing 123.4599 wouldn't it?

Or would it?

Dang, now I gotta code it and see

Regards,

Jim Langston

bmorris@ca.ibm.com wrote:

> >Date: Tue, 22 Aug 2000 15:44:28 -0500 (CDT)
> >From: Scott Klement <klemscot@klements.com>
> >
> >Ummm...  why would Z-Add be more efficient than MOVE? That seems odd to
> >me.  Math is slower than just moving bytes around...
>
> >Date: Tue, 22 Aug 2000 19:05:29 -0400
> >From: "jt" <jt@ee.net>
> >
> >I was always told that, on the S/38, MOVE and Z-ADD created the exact same
> >MI instruction.  I verified this is still true today by looking at the IRP
> >from an RPG compile by specifying GENOPT(*LIST).  Both use the same MI
> >instruction 'copy numeric value 0.0 to field X':
> >
> >CPYNV X,P'0.0'
>
> MOVE between numerics is not usually just a matter of moving bytes around.
> Also it's not the same as Z-Add.
>
> This: MOVE  123.45   P    7 4
> doesn't do the same thing as
> this: Z-ADD 123.45   P    7 4
>
> Sure, the same code is generated for Z-ADD *ZEROS and MOVE *ZEROS.  And
> maybe even occasionally for other MOVE/Z-ADD pairs. But in general, MOVE
> and Z-ADD don't generate the same code because they don't mean the same
> thing.  Try my code above.  Also, check the results.  Set P to 999.9999
> before you do the Z-ADD or the MOVE.
>
> Barbara Morris

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