It calculates greatest common divisor and is
compiled in only if CONFIG_GCD is selected.
Signed-off-by: Andrey Panov <rockford@xxxxxxxxx>
---
include/linux/gcd.h | 12 ++++++++++++
lib/Kconfig | 3 +++
lib/Makefile | 1 +
lib/gcd.c | 19 +++++++++++++++++++
4 files changed, 35 insertions(+)
create mode 100644 include/linux/gcd.h
create mode 100644 lib/gcd.c
diff --git a/include/linux/gcd.h b/include/linux/gcd.h
new file mode 100644
index 0000000..6405b27
--- /dev/null
+++ b/include/linux/gcd.h
@@ -0,0 +1,12 @@
+#ifndef _GCD_H
+#define _GCD_H
+
+#include <linux/compiler.h>
+
+#if !defined(swap)
+#define swap(x, y) do { typeof(x) z = x; x = y; y = z; } while (0)
+#endif
+
+unsigned long gcd(unsigned long a, unsigned long b) __attribute_const__;
+
+#endif /* _GCD_H */
diff --git a/lib/Kconfig b/lib/Kconfig
index 62695f1..4b9b472 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -55,6 +55,9 @@ config LIBMTD
config STMP_DEVICE
bool
+config GCD
+ bool
+
source lib/gui/Kconfig
source lib/bootstrap/Kconfig
diff --git a/lib/Makefile b/lib/Makefile
index b97e52d..6f70f01 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -52,3 +52,4 @@ obj-$(CONFIG_STMP_DEVICE) += stmp-device.o
obj-y += wchar.o
obj-y += libfile.o
obj-y += bitmap.o
+obj-$(CONFIG_GCD) += gcd.o
diff --git a/lib/gcd.c b/lib/gcd.c
new file mode 100644
index 0000000..dde8c9e
--- /dev/null
+++ b/lib/gcd.c
@@ -0,0 +1,19 @@
+#include <linux/kernel.h>
+#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;
+}
--
2.1.4
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