Hi,
On Tue, 11 Dec 2001, Benjamin LaHaise wrote:
> On Tue, Dec 11, 2001 at 09:35:15PM -0600, Steven Walter wrote:
> > > + nr_pages = (ptr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
> > > + nr_pages -= ptr >> PAGE_SHIFT;
> >
> > Isn't this the same as
> > nr_pages = (len + PAGE_SIZE -1) >> PAGE_SHIFT;
>
> No.
But this is:
nr_pages = ((ptr & ~PAGE_MASK) + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
and this even slightly better (at least on ia32):
mask = PAGE_SIZE - 1;
nr_pages = ((ptr & mask) + len + mask) >> PAGE_SHIFT;
bye, Roman
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This archive was generated by hypermail 2b29 : Sat Dec 15 2001 - 21:00:23 EST