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author | Yunhong Jiang <yunhong.jiang@intel.com> | 2015-08-04 12:17:53 -0700 |
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committer | Yunhong Jiang <yunhong.jiang@intel.com> | 2015-08-04 15:44:42 -0700 |
commit | 9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch) | |
tree | 1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/lib/int_sqrt.c | |
parent | 98260f3884f4a202f9ca5eabed40b1354c489b29 (diff) |
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base.
It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:
commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Sat Jul 25 12:13:34 2015 +0200
Prepare v4.1.3-rt3
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.
Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
Diffstat (limited to 'kernel/lib/int_sqrt.c')
-rw-r--r-- | kernel/lib/int_sqrt.c | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/kernel/lib/int_sqrt.c b/kernel/lib/int_sqrt.c new file mode 100644 index 000000000..1ef4cc344 --- /dev/null +++ b/kernel/lib/int_sqrt.c @@ -0,0 +1,38 @@ +/* + * Copyright (C) 2013 Davidlohr Bueso <davidlohr.bueso@hp.com> + * + * Based on the shift-and-subtract algorithm for computing integer + * square root from Guy L. Steele. + */ + +#include <linux/kernel.h> +#include <linux/export.h> + +/** + * int_sqrt - rough approximation to sqrt + * @x: integer of which to calculate the sqrt + * + * A very rough approximation to the sqrt() function. + */ +unsigned long int_sqrt(unsigned long x) +{ + unsigned long b, m, y = 0; + + if (x <= 1) + return x; + + m = 1UL << (BITS_PER_LONG - 2); + while (m != 0) { + b = y + m; + y >>= 1; + + if (x >= b) { + x -= b; + y += m; + } + m >>= 2; + } + + return y; +} +EXPORT_SYMBOL(int_sqrt); |