Re: Am I misunderstanding random numbers?

[KHMan <keinhong@...>]

David Kastrup wrote:
> Roberto Ierusalimschy <roberto@inf.puc-rio.br> writes:
>
> > > on my WinXP 32 bit box as well as an Ubuntu Karmic 32-bit box.
> > > This makes it pretty clear that the conversion from double to int
> > > is handling the overflow in an unexpected way. Knowing it will
> > > saturate, having -2147483649 saturate to -2147483648 is
> > > acceptable. However having 2147483649 saturate to the same value
> > > is *surprising*.
> > All values "saturate" to 0x80000000.
>
> It seems that the positive ones should rather go towards 0x7fffffff.

No, this is not saturation arithmetic, but an x86/x86-64 
architecture detail. 0x80000000 is the "indefinite integer value" 
for 32-bit results when converting, for example, when using 
CVTTSD2SI or FISTP. The indefinite integer value is a special 
value when the number is out of range or cannot be converted due 
to some reason. See the Intel/AMD docs for the details...

--
Cheers,
Kein-Hong Man (esq.)
Kuala Lumpur, Malaysia