Commit de9330d1 authored by Robert P. J. Day's avatar Robert P. J. Day Committed by Linus Torvalds

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: default avatarRobert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 582539e5
......@@ -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 */
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