On Sat, 23 Dec 2000, Sourav Sen wrote:
> In some parts of the kernel code I find expression like
>
> len = (len + ~PAGE_MASK) & PAGE_MASK ;
>
> Whats happening to len?
It's being aligned properly.
if you have a continuous array of objects that are each 8 bytes, you
create a mask that's FFFFFFF8, then if len=7, instead of doing an
operation on the last byte of the first thing and the first 7 bytes of the
second, the above expression will add 7, making len 14, then normalize it
to the last valid object address, 8. And if you start with a valid
address, you get that same address back.
justin
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This archive was generated by hypermail 2b29 : Sat Dec 23 2000 - 12:45:05 EST