Messages in this thread | | | Date | Tue, 6 Apr 1999 15:40:08 -0700 | From | David Miller <> | Subject | Re: [patch] arca-vm-2.2.5 |
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Date: Wed, 7 Apr 1999 00:19:36 +0200 (CEST) From: Ingo Molnar <mingo@chiara.csoma.elte.hu>
On Tue, 6 Apr 1999, Stephen C. Tweedie wrote:
-#define i (((unsigned long) inode)/(sizeof(struct inode) \ & ~ (sizeof(struct inode) - 1))) +#define i (((unsigned long) inode-PAGE_OFFSET)/(sizeof(struct inode) \ & ~ (sizeof(struct inode) - 1)))
...
btw. shouldnt it rather be something like:
#define log2(x) \
Look at the code just the 'i' in question will output :-)
mov inode, %o0 srlx %o0, 3, %o4
So on sparc64 atleast, it amounts to "inode >> 3". So:
(sizeof(struct inode) & ~ (sizeof(struct inode) - 1))
is 8 on sparc64. The 'i' construct is just meant to get rid of the "non significant" lower bits of the inode pointer and it does so very nicely. :-)
Later, David S. Miller davem@redhat.com
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