1 files changed, 19 insertions, 0 deletions
diff --git a/rotate.c b/rotate.c
new file mode 100644
index 0000000..5eb7696
--- /dev/null
+++ b/rotate.c
@@ -0,0 +1,19 @@
+#include <stddef.h>
+
+#include "common.h"
+
+/* rotates left */
+void rotate(char *base, size_t size, size_t shift)
+{
+	int dir = 1;
+	while (shift) {
+		while (2*shift <= size) {
+			swap(base, base + dir*shift, shift);
+			size -= shift;
+			base += shift*dir;
+		}
+		shift = size - shift;
+		base  = dir > 0 ? base + size - shift : base - shift;
+		dir  *= -1;
+	}
+}