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 discussing running 32-bit (L/LM/ST/etc) programs in AM64. BFN. Paul. On Fri, 3 Feb 2023 00:24:11 +0000, 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
