From de9330d13eac1f331e63ab1d18c506365b0151f3 Mon Sep 17 00:00:00 2001 From: "Robert P. J. Day" Date: Wed, 6 Feb 2008 01:36:54 -0800 Subject: log2.h: Define order_base_2() macro for convenience. Given a number of places in the tree that need to calculate this value explicitly, might as well just create a macro for it. (akpm: must be implemented as a macro for callee typeof() usage) Signed-off-by: Robert P. J. Day Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/log2.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'include') diff --git a/include/linux/log2.h b/include/linux/log2.h index c8cf5e8ef17..25b808631cd 100644 --- a/include/linux/log2.h +++ b/include/linux/log2.h @@ -190,4 +190,20 @@ unsigned long __rounddown_pow_of_two(unsigned long n) __rounddown_pow_of_two(n) \ ) +/** + * order_base_2 - calculate the (rounded up) base 2 order of the argument + * @n: parameter + * + * The first few values calculated by this routine: + * ob2(0) = 0 + * ob2(1) = 0 + * ob2(2) = 1 + * ob2(3) = 2 + * ob2(4) = 2 + * ob2(5) = 3 + * ... and so on. + */ + +#define order_base_2(n) ilog2(roundup_pow_of_two(n)) + #endif /* _LINUX_LOG2_H */ -- cgit v1.2.3-18-g5258