1 files changed, 38 insertions, 0 deletions
diff --git a/lib/int_sqrt.c b/lib/int_sqrt.c
new file mode 100644
index 000000000..1ef4cc344
--- /dev/null
+++ b/lib/int_sqrt.c
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2013 Davidlohr Bueso <davidlohr.bueso@hp.com>
+ *
+ *  Based on the shift-and-subtract algorithm for computing integer
+ *  square root from Guy L. Steele.
+ */
+
+#include <linux/kernel.h>
+#include <linux/export.h>
+
+/**
+ * int_sqrt - rough approximation to sqrt
+ * @x: integer of which to calculate the sqrt
+ *
+ * A very rough approximation to the sqrt() function.
+ */
+unsigned long int_sqrt(unsigned long x)
+{
+	unsigned long b, m, y = 0;
+
+	if (x <= 1)
+		return x;
+
+	m = 1UL << (BITS_PER_LONG - 2);
+	while (m != 0) {
+		b = y + m;
+		y >>= 1;
+
+		if (x >= b) {
+			x -= b;
+			y += m;
+		}
+		m >>= 2;
+	}
+
+	return y;
+}
+EXPORT_SYMBOL(int_sqrt);