for fullword, dont you want (*+3)/4 ?
From: Robert Netzlof <[email protected]>
To: [email protected]
Sent: Monday, 28 November 2016, 10:09
Subject: Re: Using ORG like CNOP
I don't think I've ever done this, but how about:
ORG (*+7)/8*8
Suppose * happens to be 8m, a multiple of 8. Then, (*+7)/8 = m, so
(*+7)/8*8 = 8m, the original value.
Now suppose * is 8m +1. Then *+7 = 8m+8, (*+7)/8 = m+1, (*+7)/8*8 =
8m+8, a multiple of 8.
For * = 8m+2, *+7 = 8m+9, (*+7)/8 = m+1, so again (*+7)/8*8 = 8m+8
That will be the result for all the remaining possible values of *
from 8m+3 through 8m+7.
The "magic" falls out of the integer arithmetic division which yields
0 for 7/8, 1 for 8/8 through 15/8.
Bob Netzlof
On 11/27/16, Charles Mills <[email protected]> wrote:
> Yeah, I have done this in the past somehow with that kind of cleverness,
> but
> it looks like the fancy new three-operand ORG instruction is intended for
> exactly this problem.
>
> (*+7)/8 can't be right -- you are dividing * by 8 which can't be right --
> but yes, I get the idea.
>
> Charles
>
> -----Original Message-----
> From: IBM Mainframe Assembler List [mailto:[email protected]]
> On Behalf Of Alan Atkinson
> Sent: Sunday, November 27, 2016 5:21 PM
> To: [email protected]
> Subject: Re: Using ORG like CNOP
>
> I'm doing this from memory - I can't face logging in.
> If I mess it up let me know and I'll pull one tomorrow from a listing.
>
> IIRC something like org (*+7)/8 will do it.
>
>
> Sent from my iPad
>
>> On Nov 27, 2016, at 8:14 PM, Charles Mills <[email protected]> wrote:
>>
>> I have a DSECT where I want to define a fullword such that the next
>> address after the fullword will be on a doubleword boundary. I would
>> like the alignment to be independent of the preceding alignment (be
> change-proof).
>>
>> CNOP 4,8 would do exactly what I want, but CNOP seems inappropriate in
>> non-executable code.
>>
>> I naively coded ORG *,8,-4. As luck would have it the existing
>> alignment was six bytes into a doubleword and so that ended up
>> effectively
> being ORG *-2.
>>
>> How do I use ORG to accomplish what I want? Can I use something like
>> what I coded but always have it ORG forwards and never backwards? I
>> could probably figure this out but hoped there was someone here who
>> knew the answer right off.
>>
>> Or should I shut up and use CNOP: "If it ain't broke, don't fix it."
>>
>> Charles
>
--
Bob Netzlof a/k/a Sweet Old Bob
