Messages in this thread Patch in this message | | | Date | Sat, 10 Nov 2007 22:53:36 -0500 (EST) | From | "Robert P. J. Day" <> | Subject | [PATCH] log2.h: Define order_base_2() macro for convenience. |
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Given a number of places in the tree that need to calculate this value explicitly, might as well just create a macro for it.
Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
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run-time tested for the first several values. note that this macro is defined strictly in terms of rounding *up* -- i've seen no places in the tree that require this expression to be rounded down, so i'm not drawing that distinction.
diff --git a/include/linux/log2.h b/include/linux/log2.h index c8cf5e8..ed121c0 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 */ -- ======================================================================== Robert P. J. Day Linux Consulting, Training and Annoying Kernel Pedantry Waterloo, Ontario, CANADA http://crashcourse.ca ======================================================================== - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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