That's correct. Your greater the 4-byte arithmetic just got easier! If
you use them in an assembler subroutine, you should save the the
incoming 64-bit register and restore it on the way out. There are
details about only saving the high half and it not being necessary for
certain registers, but in general that's your responsibility.
On 2022-01-19 1:44 p.m., Dave Clark wrote:
"IBM Mainframe Assembler List"<ASSEMBLER-LIST@LISTSERV.UGA.EDU> wrote on
01/19/2022 01:00:07 PM:
I'd suggest you clear the high-order word of R2 then use CVDG.
Would that work for you?
OK, that brings up a question that I have not had to address
before this. Up till now I've used odd-even register pairs for 64-bit
operations. But I'm given to understand that all general registers are
actually 64-bit now instead of the traditional 32-bit. Is that correct?
So, 32-bit instructions just use the low order 32 bits of the general
purpose register and 64-bit instructions automatically use the full
register -- with no register "pairs" involved. Is that correct?
Sincerely,
Dave Clark
Gary Weinhold
Senior Application Architect
DATAKINETICS | Data Performance & Optimization
Phone:+1.613.523.5500 x216
Email: weinh...@dkl.com
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