mirror of
https://github.com/torvalds/linux.git
synced 2024-11-14 08:02:07 +00:00
2c64e9cb0b
For better maintenance and expansion move the mathematic helpers to the separate folder. No functional change intended. Note, the int_sqrt() is not used as a part of lib, so, moved to regular obj. Link: http://lkml.kernel.org/r/20190323172531.80025-1-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Thierry Reding <thierry.reding@gmail.com> Cc: Lee Jones <lee.jones@linaro.org> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: Ray Jui <rjui@broadcom.com> [mchehab+samsung@kernel.org: fix broken doc references for div64.c and gcd.c] Link: http://lkml.kernel.org/r/734f49bae5d4052b3c25691dfefad59bea2e5843.1555580999.git.mchehab+samsung@kernel.org Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
71 lines
1.1 KiB
C
71 lines
1.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* 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>
|
|
#include <linux/bitops.h>
|
|
|
|
/**
|
|
* int_sqrt - computes the integer square root
|
|
* @x: integer of which to calculate the sqrt
|
|
*
|
|
* Computes: floor(sqrt(x))
|
|
*/
|
|
unsigned long int_sqrt(unsigned long x)
|
|
{
|
|
unsigned long b, m, y = 0;
|
|
|
|
if (x <= 1)
|
|
return x;
|
|
|
|
m = 1UL << (__fls(x) & ~1UL);
|
|
while (m != 0) {
|
|
b = y + m;
|
|
y >>= 1;
|
|
|
|
if (x >= b) {
|
|
x -= b;
|
|
y += m;
|
|
}
|
|
m >>= 2;
|
|
}
|
|
|
|
return y;
|
|
}
|
|
EXPORT_SYMBOL(int_sqrt);
|
|
|
|
#if BITS_PER_LONG < 64
|
|
/**
|
|
* int_sqrt64 - strongly typed int_sqrt function when minimum 64 bit input
|
|
* is expected.
|
|
* @x: 64bit integer of which to calculate the sqrt
|
|
*/
|
|
u32 int_sqrt64(u64 x)
|
|
{
|
|
u64 b, m, y = 0;
|
|
|
|
if (x <= ULONG_MAX)
|
|
return int_sqrt((unsigned long) x);
|
|
|
|
m = 1ULL << ((fls64(x) - 1) & ~1ULL);
|
|
while (m != 0) {
|
|
b = y + m;
|
|
y >>= 1;
|
|
|
|
if (x >= b) {
|
|
x -= b;
|
|
y += m;
|
|
}
|
|
m >>= 2;
|
|
}
|
|
|
|
return y;
|
|
}
|
|
EXPORT_SYMBOL(int_sqrt64);
|
|
#endif
|