add nextPow2

Author: jwu

lib/utils.js

@@ -112,4 +112,23 @@ export function randomRange(min, max) {
  */
 export function randomRangeInt(min, max) {
   return Math.floor(this.randomRange(min, max));
+}
+
+/**
+ * Returns the next power of two for the value
+ *
+ * @method nextPow2
+ * @param {number} val
+ * @return {number} the the next power of two
+ */
+export function nextPow2(val) {
+  --val;
+  val = (val >> 1) | val;
+  val = (val >> 2) | val;
+  val = (val >> 4) | val;
+  val = (val >> 8) | val;
+  val = (val >> 16) | val;
+  ++val;
+
+  return val;
 }

test/utils.spec.js

@@ -73,6 +73,18 @@ tap.test('utils', t => {
     t.end();
   });
 
+  t.test('randomRangeInt', t => {
+    let r = utils.randomRangeInt(-10, 10);
+    t.assert(r >= -10 && r <= 10);
+    t.end();
+  });
+
+  t.test('nextPow2', t => {
+    t.equal(utils.nextPow2(10), 16);
+    t.equal(utils.nextPow2(245), 256);
+    t.end();
+  });
+
   t.end();
 });