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author | Andrey Panov <rockford@yandex.ru> | 2015-03-04 23:11:29 +0300 |
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committer | Sascha Hauer <s.hauer@pengutronix.de> | 2015-03-05 09:11:33 +0100 |
commit | 78d030226d25b2c4e4cbad6228fc3f90902015c5 (patch) | |
tree | cba126ba25dacef3c4ac0a4af00648cfd69008d3 | |
parent | 09c4b63aa20e97011eb109794c7c23faf7ebdce4 (diff) | |
download | barebox-78d030226d25b2c4e4cbad6228fc3f90902015c5.tar.gz barebox-78d030226d25b2c4e4cbad6228fc3f90902015c5.tar.xz |
lib: Add gcd() function
It calculates greatest common divisor.
Signed-off-by: Andrey Panov <rockford@yandex.ru>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
-rw-r--r-- | include/linux/gcd.h | 8 | ||||
-rw-r--r-- | include/linux/kernel.h | 5 | ||||
-rw-r--r-- | lib/Makefile | 1 | ||||
-rw-r--r-- | lib/gcd.c | 18 |
4 files changed, 32 insertions, 0 deletions
diff --git a/include/linux/gcd.h b/include/linux/gcd.h new file mode 100644 index 0000000000..0ac262162d --- /dev/null +++ b/include/linux/gcd.h @@ -0,0 +1,8 @@ +#ifndef _GCD_H +#define _GCD_H + +#include <linux/kernel.h> + +unsigned long gcd(unsigned long a, unsigned long b) __attribute_const__; + +#endif /* _GCD_H */ diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 3f2644cf65..5b6b448395 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -257,5 +257,10 @@ static inline char *hex_byte_pack_upper(char *buf, u8 byte) const typeof( ((type *)0)->member ) *__mptr = (ptr); \ (type *)( (char *)__mptr - offsetof(type,member) );}) +/* + * swap - swap value of @a and @b + */ +#define swap(a, b) \ + do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0) #endif /* _LINUX_KERNEL_H */ diff --git a/lib/Makefile b/lib/Makefile index 226570a7e6..1684649dd5 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -51,3 +51,4 @@ obj-$(CONFIG_STMP_DEVICE) += stmp-device.o obj-y += wchar.o obj-y += libfile.o obj-y += bitmap.o +obj-y += gcd.o diff --git a/lib/gcd.c b/lib/gcd.c new file mode 100644 index 0000000000..86bdba9112 --- /dev/null +++ b/lib/gcd.c @@ -0,0 +1,18 @@ +#include <linux/gcd.h> + +/* Greatest common divisor */ +unsigned long gcd(unsigned long a, unsigned long b) +{ + unsigned long r; + + if (a < b) + swap(a, b); + + if (!b) + return a; + while ((r = a % b) != 0) { + a = b; + b = r; + } + return b; +} |