Re: Bug on Pentium IOC

[Dirk Zimoch <dirk.zimoch@psi.ch>]

Bernd Schoeneburg wrote:
> Hi all,
> can anyone explain this:
>
> ~(~0UL << 32)        is 0xFFFFFFFF on a Motorola VME162 i.e., which is
> correct
>                                 the same on a Pentium is 0, which is
> false!
>
> Ideas?
>
> Bernd

The Pentium (and all Intel x86s, I think) does all shifts mod 32.
Thus (~0 << 32) is not shifted at all.
=> ~(~0 << 32) = ~~0 = 0

There may be other architectures that behave similar.

Dirk

--
Dr. Dirk Zimoch
Swiss Light Source
Paul Scherrer Institut
Computing and Controls
phone +41 56 310 5182
fax   +41 56 310 4413