now version controlled.

1 files changed, 68 insertions, 0 deletions

diff --git a/gcd.c b/gcd.c
new file mode 100644
index 0000000..4fa0197
--- /dev/null
+++ b/gcd.c
@@ -0,0 +1,68 @@
+#include <u.h>
+#include <libc.h>
+
+enum {
+	Tgcd,
+	Tmod,
+	Te
+};
+vlong t[Te];
+vlong t0;
+
+void
+swap(int *a, int *b)
+{
+	int tmp;
+
+	tmp = *a;
+	*a = *b;
+	*b = tmp;
+}
+
+int
+gcd(int u, int v)
+{
+	while(u > 0){
+		if(u < v)
+			swap(&u, &v);
+		u = u-v;
+	}
+	return v;
+}
+
+int
+modgcd(int u, int v)
+{
+	while(u > 0){
+		if(u < v)
+			swap(&u, &v);
+		u = u % v;
+	}
+	return v;
+}
+
+void
+usage(void)
+{
+	fprint(2, "usage: gcd num den\n");
+	exits("usage");
+}
+
+void
+main(int argc, char *argv[])
+{
+	int n, m;
+
+	if(argc != 3)
+		sysfatal("not enough arguments");
+	n = strtol(argv[1], nil, 0);
+	m = strtol(argv[2], nil, 0);
+	t0 = nsec();
+	print("GCD %d %d = %d\n", n, m, gcd(n, m));
+	t[Tgcd] = nsec()-t0;
+	t0 = nsec();
+	print("MODGCD %d %d = %d\n", n, m, modgcd(n, m));
+	t[Tmod] = nsec()-t0;
+	print("\tgcd: %lld | mod: %lld\n", t[Tgcd], t[Tmod]);
+	exits(nil);
+}