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author | Andy Shevchenko <andriy.shevchenko@linux.intel.com> | 2019-05-14 15:43:05 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-05-14 19:52:49 -0700 |
commit | 2c64e9cb0b6b858901e9a386860d7d929d1cbaeb (patch) | |
tree | 749da0ef8f5d478680a523c877fb0e16fc18409c /lib/gcd.c | |
parent | b5c56e0cdd62979dd538e5363b06be5bdf735a09 (diff) | |
download | linux-2c64e9cb0b6b858901e9a386860d7d929d1cbaeb.tar.bz2 |
lib: Move mathematic helpers to separate folder
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>
Diffstat (limited to 'lib/gcd.c')
-rw-r--r-- | lib/gcd.c | 84 |
1 files changed, 0 insertions, 84 deletions
diff --git a/lib/gcd.c b/lib/gcd.c deleted file mode 100644 index 7948ab27f0a4..000000000000 --- a/lib/gcd.c +++ /dev/null @@ -1,84 +0,0 @@ -#include <linux/kernel.h> -#include <linux/gcd.h> -#include <linux/export.h> - -/* - * This implements the binary GCD algorithm. (Often attributed to Stein, - * but as Knuth has noted, appears in a first-century Chinese math text.) - * - * This is faster than the division-based algorithm even on x86, which - * has decent hardware division. - */ - -#if !defined(CONFIG_CPU_NO_EFFICIENT_FFS) - -/* If __ffs is available, the even/odd algorithm benchmarks slower. */ - -/** - * gcd - calculate and return the greatest common divisor of 2 unsigned longs - * @a: first value - * @b: second value - */ -unsigned long gcd(unsigned long a, unsigned long b) -{ - unsigned long r = a | b; - - if (!a || !b) - return r; - - b >>= __ffs(b); - if (b == 1) - return r & -r; - - for (;;) { - a >>= __ffs(a); - if (a == 1) - return r & -r; - if (a == b) - return a << __ffs(r); - - if (a < b) - swap(a, b); - a -= b; - } -} - -#else - -/* If normalization is done by loops, the even/odd algorithm is a win. */ -unsigned long gcd(unsigned long a, unsigned long b) -{ - unsigned long r = a | b; - - if (!a || !b) - return r; - - /* Isolate lsbit of r */ - r &= -r; - - while (!(b & r)) - b >>= 1; - if (b == r) - return r; - - for (;;) { - while (!(a & r)) - a >>= 1; - if (a == r) - return r; - if (a == b) - return a; - - if (a < b) - swap(a, b); - a -= b; - a >>= 1; - if (a & r) - a += b; - a >>= 1; - } -} - -#endif - -EXPORT_SYMBOL_GPL(gcd); |