[haiku-commits] Re: haiku: hrev44773 - src/system/kernel/vm
- From: "Ingo Weinhold" <ingo_weinhold@xxxxxx>
- To: haiku-commits@xxxxxxxxxxxxx
- Date: Wed, 07 Nov 2012 01:40:22 +0100
JÃrÃme Duval wrote:
> 2012/11/6 Ingo Weinhold <ingo_weinhold@xxxxxx>
> > > > Here the check is necessary indeed. On the other hand all the shifts
> > are
> > > > the wrong way around. I wonder why I didn't use a mask for the
> > boundary,
> > > > anyway. The checks would be similiar, but a mask doesn't need a loop
> > to be
> > > > computed.
> > >
> > > Right. You think to something like ((offsetStart ^ (offsetStart + length
> > -
> > > 1)) & ~(boundary - 1)) == 0 ?
> >
> > I was thinking of
> >
> > boundaryMask = -boundary;
> >
> > in the initialization part. And then check ((offsetStart | (offsetStart +
> > length - 1)) & boundaryMask) != 0.
>
> This doesn't work right IMO.
Yeah, not sure what I was thinking.
> Moreover boundaryMask would be a int32?
No, a page_num_t. -boundary is just a simpler way of writing ~(boundary - 1).
> I still like my proposition above :)
Me too. I'd just move the computation of the mask out of the loop.
CU, Ingo
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