> -----Original Message-----
> From: IBM Mainframe Discussion List [mailto:[email protected]]
> On Behalf Of Kirk Talman
> Sent: Wednesday, November 28, 2012 2:26 PM
> To: [email protected]
> Subject: Re: Usefullness (or not) of STOC/LOC instructions?
>
> might a lurker ask questions?
>
> if one rearranges the code at bottom as this, is the load of R2
> "cheaper"
> because it can be done in parallel w/the LT? is it worth doing if the
> JZ is taken?
>
> is 0(,R1) preferred to 0(R1) because of cost or esthetics?
I guess, in my case, it is a combination of esthetics and being concerned about
possible AR mode considerations. In AR mode:
L R2,0(,R1)
and
L R2,0(R1)
will likely result in greatly different values being loaded into R2 if the
contents of AR1 <> primary address space.
>
> LT R1,POINTER
> L R2,INTVAL
> JZ AROUND
> ST R2,0(,R1)
> AROUND DS 0H
>
> > From: "McKown, John" <[email protected]>
>
> > L R2,INTVAL
> > LT R1,POINTER
> > STOC R2,0(,R1),NZ
> >
> > instead of:
> >
> > LT R1,POINTER
> > JZ AROUND
> > L R2,INTVAL
> > ST R2,0(,R1)
> > AROUND DS 0H
> >
> > for the C construct:
> >
> > if (POINTER != NULL) *POINTER=INTVAL;
--
John McKown
Systems Engineer IV
IT
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