I have worked on some systems where the CC was the standard response
mechanism from CALL'd subroutines. Example:
CALL SENDALL,(INBUFF,OURBUFF,...)
BZ SUCCESS
BH OVERFLOW
BL SNDSHORT
BO TRYAGAIN
This is common technique with some real-time I/O and "State Table" driven
systems. As long as there are only a limited number of possible system
states, this technique is bullet proof.
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf
Of Binyamin Dissen
Sent: Monday, November 29, 2010 11:31 AM
To: [email protected]
Subject: Re: IEFBR14
On Mon, 29 Nov 2010 11:22:43 -0600 "McKown, John"
<[email protected]> wrote:
:>> -----Original Message-----
:>> From: IBM Mainframe Discussion List :>> [mailto:[email protected]] On
Behalf Of Tom Marchant :>> Sent: Monday, November 29, 2010 11:11 AM :>> To:
[email protected] :>> Subject: Re: IEFBR14
:>> On Mon, 29 Nov 2010 10:51:19 -0600, Chase, John wrote:
:>> >Wasn't there also a requirement that whatever means was :>> chosen to
zero :>> >Reg15 also set the condition code to zero?
:>> The condition code for the step is set from the value in register 15.
:>> There is no connection between that and the condition code bits in :>>
the PSW. No, there was no requirement to set the CC bits in the PSW.
:>Now that would be interesting, tho. Most code does something like:
:> CALL SOMEPGM,...
:> LTR 15,15
:> BNZ ERROR
:>Imagine if IBM had stated that that subroutine linkage should set the CC
as well as the RC in 15 so that the code could have been shorted to:
:> CALL SOMEPGM,...
:> BNZ ERROR
:>I saved 2 bytes and one instruction. Today, who cares? On an old S/360???
IIRC, that is how it works in CP (VM). But it required the called routine to
set the CC, typically via SPM.
--
Binyamin Dissen <[email protected]> http://www.dissensoftware.com
Director, Dissen Software, Bar & Grill - Israel
Should you use the mailblocks package and expect a response from me, you
should preauthorize the dissensoftware.com domain.
I very rarely bother responding to challenge/response systems, especially
those from irresponsible companies.
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