Test for power of two safely

third_party/WebKit/Source/platform/audio/AudioUtilities.cpp

 /*
  * Copyright (C) 2010, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 55 matching lines @@
 float minAudioBufferSampleRate() {
   // crbug.com/344375
   return 3000;
 }
 
 float maxAudioBufferSampleRate() {
   // <video> tags support sample rates up 384 kHz so audio context
   // should too.
   return 384000;
 }
+
+bool isPowerOfTwo(size_t x) {
+  // From Hacker's Delight.  x & (x - 1) turns off (zeroes) the
+  // rightmost 1-bit in the word x.  If x is a power of two, then the
+  // result is, of course, 0.
+  return x > 0 && ((x & (x - 1)) == 0);
+}
+
 }  // namespace AudioUtilities
 
 }  // namespace blink