On Tue, 19 Aug 2025 01:35:52 +0000, James Mulder <[email protected]> wrote:
> The upper half of R14 is irrelevant for BSM 0,14 > when the target AMODE is 24 or 31. > >and bit 63 of the register is zero, Your doc snip says bit 63 must be 0 which means the upper half of R14 is relevant and R14 must be completely restored (64-bit). If you don't restore it and bit 63 is a 1, then you have an invalid 64 bit address. > Bit 32 means bit 32 of the 64 bit register (with bits numbered from 0-63), > which is the high order bit of the low order half of the register. I mentioned bit 32 being bit 31 for others because they are accustomed to POPS which refers to this as bit 31 as seen in your POPS snippet. >When the contents of general register R2 are used >and bit 63 of the register is zero, bit 31 of the current >PSW, the extended-addressing-mode bit, is set to >zero, bit 32 of the register specifies the new basic >addressing mode and replaces bit 32 of the PSW, With your BSM snippet from the POPS and the R14 doc from LINKX, would an average person figure out how to BSM R14 with new documentation? You could just document BR R14 because you know it works for all AMODES and forget about BSM because it's harder for average people to use. >When the caller is AMode 31 or 64, the high order bit >of R14 is 1 when the target module is AMode 24 or 31, > and 0 when the target module is AMode 64. Bit 63 is relevant to BSM as documented in your POPS BSM snip. Your tests ignored the upper half of R14 which must be either x'80000000' or x'00000000' otherwise BR R14 would abend in AMODE64. Probably the first, which identifies AMODE64 and begs the question why R15 when callers AMODE64 is bit 63 of R14. > I will submit a documentation update This will make Binyamin and others extremely happy. Many thanks for the excellent work. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
