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 <[email protected]>
---
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
========================================================================
On Sat, 10 Nov 2007 22:53:36 -0500 (EST) Robert P. J. Day wrote:
>
> 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 <[email protected]>
>
> ---
>
> 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
* @n: argument
(mostly changing - to :)
> + *
> + * 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 */
>
> --
---
~Randy
On Sun, 11 Nov 2007, Randy Dunlap wrote:
> On Sat, 10 Nov 2007 22:53:36 -0500 (EST) Robert P. J. Day wrote:
> >
> > +/**
> > + * order_base_2 - calculate the (rounded up) base 2 order of the argument
> > + * @n - parameter
>
> * @n: argument
>
> (mostly changing - to :)
ah, yes, fix coming shortly.
rday