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
