Basically, yes. Some instructions always use all 64-bis of the register.
However others, like LA are addressing mode sensitive.
Robert Ngan
DXC Luxoft
-----Original Message-----
From: IBM Mainframe Assembler List <ASSEMBLER-LIST@LISTSERV.UGA.EDU> On Behalf
Of Dave Clark
Sent: Wednesday, January 19, 2022 12:45
To: ASSEMBLER-LIST@LISTSERV.UGA.EDU
Subject: 64-bit registers (was: Unsigned Binary Formats)
"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
--
Winsupply Group Services
3110 Kettering Boulevard
Dayton, Ohio 45439 USA
(937) 294-5331
*********************************************************************************************
This email message and any attachments is for use only by the named
addressee(s) and may contain confidential, privileged and/or proprietary
information. If you have received this message in error, please
immediately notify the sender and delete and destroy the message and all
copies. All unauthorized direct or indirect use or disclosure of this
message is strictly prohibited. No right to confidentiality or privilege
is waived or lost by any error in transmission.
*********************************************************************************************
