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
9#include <stddef.h>
10
11#include <limits>
12
13#include "testing/gtest/include/gtest/gtest.h"
14
15namespace base {
16namespace bits {
17
18TEST(BitsTest, Log2Floor) {
19  EXPECT_EQ(-1, Log2Floor(0));
20  EXPECT_EQ(0, Log2Floor(1));
21  EXPECT_EQ(1, Log2Floor(2));
22  EXPECT_EQ(1, Log2Floor(3));
23  EXPECT_EQ(2, Log2Floor(4));
24  for (int i = 3; i < 31; ++i) {
25    unsigned int value = 1U << i;
26    EXPECT_EQ(i, Log2Floor(value));
27    EXPECT_EQ(i, Log2Floor(value + 1));
28    EXPECT_EQ(i, Log2Floor(value + 2));
29    EXPECT_EQ(i - 1, Log2Floor(value - 1));
30    EXPECT_EQ(i - 1, Log2Floor(value - 2));
31  }
32  EXPECT_EQ(31, Log2Floor(0xffffffffU));
33}
34
35TEST(BitsTest, Log2Ceiling) {
36  EXPECT_EQ(-1, Log2Ceiling(0));
37  EXPECT_EQ(0, Log2Ceiling(1));
38  EXPECT_EQ(1, Log2Ceiling(2));
39  EXPECT_EQ(2, Log2Ceiling(3));
40  EXPECT_EQ(2, Log2Ceiling(4));
41  for (int i = 3; i < 31; ++i) {
42    unsigned int value = 1U << i;
43    EXPECT_EQ(i, Log2Ceiling(value));
44    EXPECT_EQ(i + 1, Log2Ceiling(value + 1));
45    EXPECT_EQ(i + 1, Log2Ceiling(value + 2));
46    EXPECT_EQ(i, Log2Ceiling(value - 1));
47    EXPECT_EQ(i, Log2Ceiling(value - 2));
48  }
49  EXPECT_EQ(32, Log2Ceiling(0xffffffffU));
50}
51
52TEST(BitsTest, Align) {
53  const size_t kSizeTMax = std::numeric_limits<size_t>::max();
54  EXPECT_EQ(0ul, Align(0, 4));
55  EXPECT_EQ(4ul, Align(1, 4));
56  EXPECT_EQ(4096ul, Align(1, 4096));
57  EXPECT_EQ(4096ul, Align(4096, 4096));
58  EXPECT_EQ(4096ul, Align(4095, 4096));
59  EXPECT_EQ(8192ul, Align(4097, 4096));
60  EXPECT_EQ(kSizeTMax - 31, Align(kSizeTMax - 62, 32));
61  EXPECT_EQ(kSizeTMax / 2 + 1, Align(1, kSizeTMax / 2 + 1));
62}
63
64}  // namespace bits
65}  // namespace base
66