1 files changed, 30 insertions, 0 deletions
diff --git a/lib/int_sqrt.c b/lib/int_sqrt.c
index e2d3290..14436f4 100644
--- a/lib/int_sqrt.c
+++ b/lib/int_sqrt.c
@@ -38,3 +38,33 @@ unsigned long int_sqrt(unsigned long x)
 	return y;
 }
 EXPORT_SYMBOL(int_sqrt);
+
+#if BITS_PER_LONG < 64
+/**
+ * int_sqrt64 - strongly typed int_sqrt function when minimum 64 bit input
+ * is expected.
+ * @x: 64bit integer of which to calculate the sqrt
+ */
+u32 int_sqrt64(u64 x)
+{
+	u64 b, m, y = 0;
+
+	if (x <= ULONG_MAX)
+		return int_sqrt((unsigned long) x);
+
+	m = 1ULL << (fls64(x) & ~1ULL);
+	while (m != 0) {
+		b = y + m;
+		y >>= 1;
+
+		if (x >= b) {
+			x -= b;
+			y += m;
+		}
+		m >>= 2;
+	}
+
+	return y;
+}
+EXPORT_SYMBOL(int_sqrt64);
+#endif