1 files changed, 27 insertions, 0 deletions
diff --git a/src/dotty/tools/dotc/util/SixteenNibbles.scala b/src/dotty/tools/dotc/util/SixteenNibbles.scala
new file mode 100644
index 000000000..58d4a1182
--- /dev/null
+++ b/src/dotty/tools/dotc/util/SixteenNibbles.scala
@@ -0,0 +1,27 @@
+package dotty.tools.dotc.util
+
+/** An efficient implementation of sequences of 16 indexed elements with
+ *  values 0..15 in a single Long.
+ *
+ */
+class SixteenNibbles(val bits: Long) extends AnyVal {
+  import SixteenNibbles._
+
+  def apply(idx: Int): Int =
+    (bits >>> (idx * Width)).toInt & Mask
+
+  def updated(idx: Int, value: Int): SixteenNibbles =
+    new SixteenNibbles(
+      (bits & ~(Mask << (idx * Width))) |
+      ((value & Mask).toLong << (idx * Width)))
+
+  def elements: IndexedSeq[Int] = (0 until 16) map apply
+
+  override def toString =
+    s"SixteenNibbles(${elements.mkString(", ")})"
+}
+
+object SixteenNibbles {
+  final val Width = 4
+  final val Mask = (1 << Width) - 1
+}
+\ No newline at end of file