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Message-ID: <alpine.LFD.0.9999.0711120230560.9879@localhost.localdomain> Date: Mon, 12 Nov 2007 02:32:04 -0500 (EST) From: "Robert P. J. Day" <rpjday@...shcourse.ca> To: Linux Kernel Mailing List <linux-kernel@...r.kernel.org> cc: Andrew Morton <akpm@...l.org> Subject: [PATCH] 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. Signed-off-by: Robert P. J. Day <rpjday@...shcourse.ca> --- 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@...r.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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