Moved bits.h from O3D to Chrome base.

base/bits_unittest.cc

+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// This file contains the unit tests for the bit utilities.
+
+#include "base/bits.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+namespace bits {
+
+TEST(BitsTest, Log2Floor) {
+  EXPECT_EQ(-1, Log2Floor(0));
+  EXPECT_EQ(0, Log2Floor(1));
+  EXPECT_EQ(1, Log2Floor(2));
+  EXPECT_EQ(1, Log2Floor(3));
+  EXPECT_EQ(2, Log2Floor(4));
+  for (int i = 3; i < 31; ++i) {
+    unsigned int value = 1U << i;
+    EXPECT_EQ(i, Log2Floor(value));
+    EXPECT_EQ(i, Log2Floor(value + 1));
+    EXPECT_EQ(i, Log2Floor(value + 2));
+    EXPECT_EQ(i - 1, Log2Floor(value - 1));
+    EXPECT_EQ(i - 1, Log2Floor(value - 2));
+  }
+  EXPECT_EQ(31, Log2Floor(0xffffffffU));
+}
+
+TEST(BitsTest, Log2Ceiling) {
+  EXPECT_EQ(-1, Log2Ceiling(0));
+  EXPECT_EQ(0, Log2Ceiling(1));
+  EXPECT_EQ(1, Log2Ceiling(2));
+  EXPECT_EQ(2, Log2Ceiling(3));
+  EXPECT_EQ(2, Log2Ceiling(4));
+  for (int i = 3; i < 31; ++i) {
+    unsigned int value = 1U << i;
+    EXPECT_EQ(i, Log2Ceiling(value));
+    EXPECT_EQ(i + 1, Log2Ceiling(value + 1));
+    EXPECT_EQ(i + 1, Log2Ceiling(value + 2));
+    EXPECT_EQ(i, Log2Ceiling(value - 1));
+    EXPECT_EQ(i, Log2Ceiling(value - 2));
+  }
+  EXPECT_EQ(32, Log2Ceiling(0xffffffffU));
+}
+
+}  // namespace bits
+}  // namespace base