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diff --git a/o3d/base/cross/bits.h b/o3d/base/cross/bits.h
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+/*
+ * Copyright 2009, 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:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+
+// This file defines some bit utilities.
+
+#ifndef O3D_BASE_CROSS_BITS_H_
+#define O3D_BASE_CROSS_BITS_H_
+
+#include "base/logging.h"
+
+namespace o3d {
+namespace base {
+namespace bits {
+
+// Returns the integer i such as 2^i <= n < 2^(i+1)
+static inline int Log2Floor(unsigned int n) {
+  if (n == 0)
+    return -1;
+  int log = 0;
+  unsigned int value = n;
+  for (int i = 4; i >= 0; --i) {
+    int shift = (1 << i);
+    unsigned int x = value >> shift;
+    if (x != 0) {
+      value = x;
+      log += shift;
+    }
+  }
+  DCHECK_EQ(value, 1);
+  return log;
+}
+
+// Returns the integer i such as 2^(i-1) < n <= 2^i
+static inline int Log2Ceiling(unsigned int n) {
+  if (n == 0) {
+    return -1;
+  } else {
+    // Log2Floor returns -1 for 0, so the following works correctly for n=1.
+    return 1 + Log2Floor(n - 1);
+  }
+}
+
+}  // namespace bits
+}  // namespace base
+}  // namespace o3d
+
+#endif  // O3D_BASE_CROSS_BITS_H_