>doesn't current z model have a specific Unsigned Multiply instruction?<
ML, MLR, MLG, and MLGR called "Multiply Logical" are unsigned with no cc change
since overflow does not occur with 64 and 128 bit results.
Don Higgins
d...@higgins.net
www.don-higgins.net
-----Original Message-----
From: IBM Mainframe Assembler List <ASSEMBLER-LIST@LISTSERV.UGA.EDU> On Behalf
Of Paul Gilmartin
Sent: Wednesday, April 20, 2022 10:55 AM
To: ASSEMBLER-LIST@LISTSERV.UGA.EDU
Subject: Re: Detection of integer overflow
On Apr 20, 2022, at 07:46:49, Ian Worthington wrote:
>
> Whilst looking at reliable techniques to detect signed and unsigned overflow
> in integer multiplication I was checking out the late John Erhman's
> "Assembler Language Programming for IBM System z™ Servers" in which I
> discovered he presented this problem and solution:
> 18.2.13.(2)+ A programmer wanted to test whether the product of two
> positive 32-bit binary integers was too large to fit in a 32-bit
> register. <snip>
>
I have relied on:
Multiply
SLDA 32
Test CC for overflow.
Works for signed integers in any quadrant.
Does "positive" mean both sign bits are zero?
Harder for unsigned. For that reason, doesn't current z model have a specific
Unsigned Multiply instruction?
--
gil
