Program entry? Sorry, I missed that. I thought that you were addressing clearing only bits 0-31. But that leaves the caller responsible for clearing bits 0-31 of, e.g., R1.
________________________________________ From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> on behalf of Paul Edwards <mutazi...@gmail.com> Sent: Thursday, February 2, 2023 7:50 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: GETMAIN LOC=32 We're in agreement then. So what's the issue? In my first message I proposed doing: LA R3,0 etc for all undefined registers, at program entry. So that when running as AM64 the top 32 bits would be cleared. That's all. BFN. Paul. On Fri, 3 Feb 2023 00:47:35 +0000, Seymour J Metz <sme...@gmu.edu> wrote: >No, I'm claiming that LA R1,0(,R1) doesn't clear bits 0-31. Specifying base >and index as 0 is a special case and clears all but the 12 bits of the >displacement. > >________________________________________ >From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> on behalf of >Paul Edwards <mutazi...@gmail.com> >Sent: Thursday, February 2, 2023 7:36 PM >To: IBM-MAIN@LISTSERV.UA.EDU >Subject: Re: GETMAIN LOC=32 > >Are you claiming that: > >LA R3,0 > >in M664 > >does not clear bits 0-31? > >What are you looking at in the POP (which I quoted)? > >Are you able to run a test program that demonstrates that? > >ie: > >LG R3,=X'FFFFFFFFFFFFFFFF' >LGR R4,R3 >LA R3,0 > >DC H'0' > >and show me the regiseers? > >I can't easily do that myself. > >Thanks. Paul. > > > > >On Fi,, 3 Feb 2023 00:30:11 +0000, Seymour J Metz <sme...@gmu.edu> wrote: > >>Yes, I know that the wording is different depending on the mode. The point >>isd that in no addressing mode does LA clear bits 0-31 to zero. >> >> >>-- >>Shmuel (Seymour J.) Metz >>http://mason.gmu.edu/~smetz3 >> >>________________________________________ >>From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of >>Paul Edwards [mutazi...@gmail.com] >>Sent: Thursday, February 2, 2023 7:26 PM >>To: IBM-MAIN@LISTSERV.UA.EDU >>Subject: Re: GETMAIN LOC=32 >> >>Those words are not used for AM64. >> >>I am siscussing running 32-bit (L/LM/ST/etc) programs in AM64. >> >>BFN. Paul. >> >> >> >> >>On Fri, 3 Feb 2023 00:24:11 +0000S Seymour J Metz <sme...@gmu.edu> wrote: >> >>>"and bits 0-31 remain unchanged" does not mean set to zero. >>> >>> >>>-- >>>Shmuel (Seymour J.) Metz >>>http://mason.gmu.edu/~smetz3 >>> >>>________________________________________ >>>From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of >>>Paul Edwards [mutazi...@gmail.com] >>>Sent: Thursday, February 2, 2023 6:47 PM >>>To: IBM-MAIN@LISTSERV.UA.EDU >>>Subject: Re: GETMAIN LOC=32 >>> >>>On Thu, 2 Feb 2023 23:37:16 +0000, Seymour J Metz <sme...@gmu.edu> wrote: >>> >>>>The semantics of LA are that it doesn't clear the top half in AM64. >>> >>>LOAD ADDRESS >>> >>>LA R�,D�(X�,B�) [RX] >>> >>>In the 24-bit addressing mode, the address is >>>placed in bit positions 40-63, bits 32-39 are set to >>>zeros, and bits 0-31 remain unchanged.. In the >>>31-bit addressing mode, the address is placed in >>>bit positions 33-63, bit 32 is set to zero, and bits >>>0-31 remain unchanged. In the 64-bit addressing >>>mode, the address is placed in bit positions 0-63. >>> >>> >>>Ergo, LA R3,0 in AM64 will set the entire 64 bits of R3 to 0. >>> >>>Which is all I need. >>> >>>And a S/370 instruction. >>> >>>> Even if you clear the top halves yourself, there are still coding >>>> issues for 31-bit addresses in AM64. >>> >>>Fix the coding issues so that they are AM32/64-clean? >>> >>>Also they aren't really 31-bit addresses. If an "L" instruction >>>is used to load an address, it is a 32-bit address, which will >>>suddenly be visible when running in AM64 (or a restored >>>360/67 running as AM32). >>> >>>BFN. Paul. >>> >>> >>> >>>>-- >>>>Shmuel (Seymour J.) Metz >>>>http://mason.gmu.edu/~smetz3 >>>> >>>>________________________________________ >>>>From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of >>>>Paul Edwards [mutazi...@gmail.com] >>>>Sent: Thursday, February 2, 2023 6:24 PM >>>>To: IBM-MAIN@LISTSERV.UA.EDU >>>>Subject: Re: GETMAIN LOC=32 >>>> >>>>On Thu, 2 Feb 2023 23:22:00 +0000, Seymour J Metz <sme...@gmu.edu> wrote: >>>> >>>>>> And given that the high 32 bits are required to be 0, by convention, >>>>> >>>>>Where do you see that? >>>> >>>>That was my first message in the last 24 hours. >>>> >>>>Do an LA on program entry, for all undefined registers. >>>> >>>>Maybe I should have said "proposed convention". I'm happy >>>>to switch semantics to whatever is less confusing. >>>> >>>>BFN. Paul. >>>> >>>>---------------------------------------------------------------------- >>>>For IBM-MAIN subscribe / signoff / archive access instructions, >>>>send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN >>>> >>>>---------------------------------------------------------------------- >>>>For IBM-MAIN subscribe / signoff / archive access instructions, >>>>send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN >>> >>>---------------------------------------------------------------------- >>>For IBM-MAIN subscribe / signoff / archive access instructions, >>>send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN >>> >>>---------------------------------------------------------------------- >>>For IBM-MAIN subscribe / signoff / archive access instructions, >>>send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN >> >>---------------------------------------------------------------------- >>For IBM-MAIN subscribe / signoff / archive access instructions, >>send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN >> >>---------------------------------------------------------------------- >>For IBM-MAIN subscribe / signoff / archive access instructions, >>send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN > >---------------------------------------------------------------------- >For IBM-MAIN subscribe / signoff / archive access instructions, >send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN > > >---------------------------------------------------------------------- >For IBM-MAIN subscribe / signoff / archive access instructions, >send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
