smetz3
:>>
:>>
:>> ________
:>> From: IBM Mainframe Assembler List on
behalf of Tony Thigpen
:>> Sent: Tuesday, August 11, 2020 1:57 PM
:>> To: ASSEMBLER-LIST@LISTSERV.UGA.EDU
:>> Subject: how to return?
:>>
Yes. BAL from 24-bit is a special case. In amode 31, it's fine.
sas
On Sat, Aug 15, 2020 at 1:30 PM Martin Trübner wrote:
>
> >> The "special" cases, especially when R14 is loaded up separatelyWould
> you being reached by a BAL consider a special case? L
> 15,whereverI.e. BAL
cht Von: Steve Smith
Datum: 15.08.20 18:43 (GMT+01:00) An: ASSEMBLER-LIST@LISTSERV.UGA.EDU
Betreff: Re: how to return? Let's see how good you are. Given those
requirements, the only thing your subroutine needs to do isreturn with BSM
0,R14. It will do the right thing in every cas
Given those requirements, the only thing your subroutine needs to do is
return with BSM 0,R14. It will do the right thing in every case you
mentioned.
As you didn't originally specify much of this, we had to qualify answers
with various unlikely scenarios. Fact is, BSM 0,R14 works correctly for
Tony,
>> 14) And to make it even more challenging, the code *must* run in a older
>> processor that does not support branch-retaliative nor BAKR/PR
>> instructions.
Where would someone find such a processor?
Facts are:
1.) BAKR/PR are around for very long time.
2.) The stack needs an
I didn't follow the whole discussion, but I now got interested because
of the challenge and
then I looked (again) at the original solution. IMO, the original
solution is very elegant and
solves the problem. I don't see any problem with it.
In contrast, at a former customer of mine, where we
on.gmu.edu/~smetz3
From: IBM Mainframe Assembler List on behalf of
Tony Thigpen
Sent: Friday, August 14, 2020 6:23 PM
To: ASSEMBLER-LIST@LISTSERV.UGA.EDU
Subject: Re: how to return? Let's see how good you are.
I have been reading all the "that is
6:23 PM
To: ASSEMBLER-LIST@LISTSERV.UGA.EDU
Subject: Re: how to return? Let's see how good you are.
I have been reading all the "that is not a good way to do it" posts, so
here it the challenge to all those nay-sayers.
It's time to 'put-up' or 'shut-up'.
Under the following conditions
MBLER-LIST@LISTSERV.UGA.EDU
Subject: how to return?
I came across the following code today. The program can either be called
by JCL or from either an HLL or assembler program. While I included some
extra code for clarity, the code I am asking for comments on is the code
that 'fixes' R14 so that
Simpler is safer.
--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3
From: IBM Mainframe Assembler List on behalf
of Tony Thigpen
Sent: Tuesday, August 11, 2020 1:57 PM
To: ASSEMBLER-LIST@LISTSERV.UGA.EDU
Subject: how to return?
I came across
:33 PM
To: ASSEMBLER-LIST@LISTSERV.UGA.EDU
Subject: Re: how to return?
Too clever by far. Offhand I don't think I would give it a passing grade in a
code review.
I can't immediately think of situations where it might fail, but I have the
sneaking suspicion that what I don't know (and that's
Summary:
If you want to return in the AMODE of the caller:
-- If you can be entered by BASSM, you must not BSM 14,0.
-- If you cannot be entered by BASSM but could be entered by something
other than a BASR-like instruction
(including BALR in AMODE 24, LA/B and others), and don't want to run in
Thanks; I was confused by some of the responses and re-responses.
On 2020-08-12 5:34 p.m., Steve Smith wrote:
The goal should be to return to the caller in its amode, as that's
undoubtedly what it expects.
If a program is invoked via BASSM (or BSM), the amode in effect at entry is
NOT the
The goal should be to return to the caller in its amode, as that's
undoubtedly what it expects.
If a program is invoked via BASSM (or BSM), the amode in effect at entry is
NOT the caller's amode, other than by chance. So if you save the amode at
your entry, and use that for return, you will
That was my point; If the goal is to allow the called program to switch
to amode 31 and return to the caller in the amode it was in, it appears
Binjamin's 2 instructions are sufficient. The original code is checking
to see if they need to do this (and there is a small exposure because
the
Absolutely not. Binyamin qualified his answer with "... where the mode you
wish to return in is the same at entry to the routine." When called by
BASSM, that is not the case.
The OP's code was to solve a particular problem with a particular program.
Nothing about it should be taken as good for
Gary,
>> Are we to conclude from that this discussion that this is a reliable way
>> to ensure that an AMODE 31 subroutine returns control to its caller
>> in the correct amode?
the code Tony had was to ensure that it can switch to whatever mode
a routine to be called from that code needs
Are we to conclude from that this discussion that this is a reliable way
to ensure that an AMODE 31 subroutine returns control to its caller in
the correct amode?
From Binjamin's response, it appears that checking the opcode of the
previous instruction was unnecessary and perhaps, depending on
I talked to the author of the code.
1) The original program that this code was coded within actually was a
glue phase that replaced a vendor provided phase that was always called
using an api macro provided by the vendor to the customer.
2) At one point, the vendor was 24bit, but later
Uops
Binjamin, I see my error
--
Martin
On Wed, 12 Aug 2020 11:15:38 +0200 Martin Truebner
wrote:
:>Binjamin,
:>your sequence
:> LA14,0(,14) Fix-up address (in case 24 bit)
:> BSM 14,0 Now BSM 0,14 will restore the current amode
:>Will clear the amode-bit and BSM will set to that mode (0=24) and go
:>there.
I would
Binjamin,
your sequence
LA14,0(,14) Fix-up address (in case 24 bit)
BSM 14,0 Now BSM 0,14 will restore the current amode
Will clear the amode-bit and BSM will set to that mode (0=24) and go
there.
If you are very lucky you are never called in 31 bit mode then the code
will
Looking more at the description of the problem, you want to use BSM to return
no matter how called, where the mode you wish to return in is the same at
entry to the routine.
The following sequence will do it much more easily:
LA14,0(,14) Fix-up address (in case 24 bit
ay, August 11, 2020 3:42 PM
To: ASSEMBLER-LIST@LISTSERV.UGA.EDU
Subject: Re: how to return?
Suppose the return address is loaded into R14 instead of a link type
instruction and R14 points to the first byte of a page
In addition, when a program is attached, R14 usually points to CVTE
day, August 11, 2020 11:33 AM
To: ASSEMBLER-LIST@LISTSERV.UGA.EDU
Subject: Re: how to return?
Too clever by far. Offhand I don't think I would give it a passing grade in
a code review.
I can't immediately think of situations where it might fail, but I have the
sneaking suspicion that what I don't k
Re: how to return?
Too clever by far. Offhand I don't think I would give it a passing grade in
a code review.
I can't immediately think of situations where it might fail, but I have the
sneaking suspicion that what I don't know (and that's a lot) could bite that
code.
Peter
-Original Mess
On 2020-08-11 13:57, Tony Thigpen wrote:
code that 'fixes' R14
Personally, I'm not a fan of that. I want to see the caller's actual R14.
> CLI 0(R14),X'0C'BASSM?
> BER14_OK
> CLI 0(R14),X'0D'BSM?
> BER14_OK
The program
On Tue, Aug 11, 2020 at 12:57 PM Tony Thigpen wrote:
> I came across the following code today. The program can either be called
> by JCL or from either an HLL or assembler program. While I included some
> extra code for clarity, the code I am asking for comments on is the code
> that 'fixes' R14
Well, if you are sure that you know the callers that the only choice is BASSM,
BSM() or BA(L/S)R I would suggest making a standard of how the routine is
called.
Have you considered the effect of being invoked via BALR in 24 bit mode?
On Tue, 11 Aug 2020 13:57:23 -0400 Tony Thigpen wrote:
Tony,
what is done is this:
was I reached by code that saved the callers mode (and passed
in my mode) the it is safe to return with a BSM
otherwise... I save the callers mode and later return to that
(I is the pgm...)
Apparently the code intents to switch mode (likely to be 24 to 31)
: IBM Mainframe Assembler List On Behalf
Of Ed Jaffe
Sent: Tuesday, August 11, 2020 2:15 PM
To: ASSEMBLER-LIST@LISTSERV.UGA.EDU
Subject: Re: how to return?
Clever...
On 8/11/2020 10:57 AM, Tony Thigpen wrote:
> I came across the following code today. The program can either be
> called
Clever...
On 8/11/2020 10:57 AM, Tony Thigpen wrote:
I came across the following code today. The program can either be
called by JCL or from either an HLL or assembler program. While I
included some extra code for clarity, the code I am asking for
comments on is the code that 'fixes' R14 so
I came across the following code today. The program can either be called
by JCL or from either an HLL or assembler program. While I included some
extra code for clarity, the code I am asking for comments on is the code
that 'fixes' R14 so that a BSM can be used instead of a BR. I just
thought
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