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authorAndrey Panov <rockford@yandex.ru>2015-03-04 23:11:29 +0300
committerSascha Hauer <s.hauer@pengutronix.de>2015-03-05 09:11:33 +0100
commit78d030226d25b2c4e4cbad6228fc3f90902015c5 (patch)
treecba126ba25dacef3c4ac0a4af00648cfd69008d3
parent09c4b63aa20e97011eb109794c7c23faf7ebdce4 (diff)
downloadbarebox-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.h8
-rw-r--r--include/linux/kernel.h5
-rw-r--r--lib/Makefile1
-rw-r--r--lib/gcd.c18
4 files changed, 32 insertions, 0 deletions
diff --git a/include/linux/gcd.h b/include/linux/gcd.h
new file mode 100644
index 000000000..0ac262162
--- /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 3f2644cf6..5b6b44839 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 226570a7e..1684649dd 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 000000000..86bdba911
--- /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;
+}