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 AM64 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 registers? I can't easily do that myself. Thanks. Paul. On Fri, 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
