1// Copyright (c) 2009 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5// This file contains the unit tests for the bit utilities.
6
7#include "base/bits.h"
8#include "testing/gtest/include/gtest/gtest.h"
9
10namespace base {
11namespace bits {
12
13TEST(BitsTest, Log2Floor) {
14  EXPECT_EQ(-1, Log2Floor(0));
15  EXPECT_EQ(0, Log2Floor(1));
16  EXPECT_EQ(1, Log2Floor(2));
17  EXPECT_EQ(1, Log2Floor(3));
18  EXPECT_EQ(2, Log2Floor(4));
19  for (int i = 3; i < 31; ++i) {
20    unsigned int value = 1U << i;
21    EXPECT_EQ(i, Log2Floor(value));
22    EXPECT_EQ(i, Log2Floor(value + 1));
23    EXPECT_EQ(i, Log2Floor(value + 2));
24    EXPECT_EQ(i - 1, Log2Floor(value - 1));
25    EXPECT_EQ(i - 1, Log2Floor(value - 2));
26  }
27  EXPECT_EQ(31, Log2Floor(0xffffffffU));
28}
29
30TEST(BitsTest, Log2Ceiling) {
31  EXPECT_EQ(-1, Log2Ceiling(0));
32  EXPECT_EQ(0, Log2Ceiling(1));
33  EXPECT_EQ(1, Log2Ceiling(2));
34  EXPECT_EQ(2, Log2Ceiling(3));
35  EXPECT_EQ(2, Log2Ceiling(4));
36  for (int i = 3; i < 31; ++i) {
37    unsigned int value = 1U << i;
38    EXPECT_EQ(i, Log2Ceiling(value));
39    EXPECT_EQ(i + 1, Log2Ceiling(value + 1));
40    EXPECT_EQ(i + 1, Log2Ceiling(value + 2));
41    EXPECT_EQ(i, Log2Ceiling(value - 1));
42    EXPECT_EQ(i, Log2Ceiling(value - 2));
43  }
44  EXPECT_EQ(32, Log2Ceiling(0xffffffffU));
45}
46
47}  // namespace bits
48}  // namespace base
49