1 // Copyright 2009 The Chromium Authors
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 <cstddef>
8 #include <limits>
9
10 #include "partition_alloc/partition_alloc_base/bits.h"
11 #include "testing/gtest/include/gtest/gtest.h"
12
13 namespace partition_alloc::internal::base::bits {
14
TEST(BitsTestPA,Log2Floor)15 TEST(BitsTestPA, Log2Floor) {
16 EXPECT_EQ(-1, Log2Floor(0));
17 EXPECT_EQ(0, Log2Floor(1));
18 EXPECT_EQ(1, Log2Floor(2));
19 EXPECT_EQ(1, Log2Floor(3));
20 EXPECT_EQ(2, Log2Floor(4));
21 for (int i = 3; i < 31; ++i) {
22 unsigned int value = 1U << i;
23 EXPECT_EQ(i, Log2Floor(value));
24 EXPECT_EQ(i, Log2Floor(value + 1));
25 EXPECT_EQ(i, Log2Floor(value + 2));
26 EXPECT_EQ(i - 1, Log2Floor(value - 1));
27 EXPECT_EQ(i - 1, Log2Floor(value - 2));
28 }
29 EXPECT_EQ(31, Log2Floor(0xffffffffU));
30 }
31
TEST(BitsTestPA,Log2Ceiling)32 TEST(BitsTestPA, Log2Ceiling) {
33 EXPECT_EQ(-1, Log2Ceiling(0));
34 EXPECT_EQ(0, Log2Ceiling(1));
35 EXPECT_EQ(1, Log2Ceiling(2));
36 EXPECT_EQ(2, Log2Ceiling(3));
37 EXPECT_EQ(2, Log2Ceiling(4));
38 for (int i = 3; i < 31; ++i) {
39 unsigned int value = 1U << i;
40 EXPECT_EQ(i, Log2Ceiling(value));
41 EXPECT_EQ(i + 1, Log2Ceiling(value + 1));
42 EXPECT_EQ(i + 1, Log2Ceiling(value + 2));
43 EXPECT_EQ(i, Log2Ceiling(value - 1));
44 EXPECT_EQ(i, Log2Ceiling(value - 2));
45 }
46 EXPECT_EQ(32, Log2Ceiling(0xffffffffU));
47 }
48
TEST(BitsTestPA,AlignUp)49 TEST(BitsTestPA, AlignUp) {
50 static constexpr size_t kSizeTMax = std::numeric_limits<size_t>::max();
51 EXPECT_EQ(0u, AlignUp(0u, 4u));
52 EXPECT_EQ(4u, AlignUp(1u, 4u));
53 EXPECT_EQ(4096u, AlignUp(1u, 4096u));
54 EXPECT_EQ(4096u, AlignUp(4096u, 4096u));
55 EXPECT_EQ(4096u, AlignUp(4095u, 4096u));
56 EXPECT_EQ(8192u, AlignUp(4097u, 4096u));
57 EXPECT_EQ(kSizeTMax - 31, AlignUp(kSizeTMax - 62, size_t{32}));
58 EXPECT_EQ(kSizeTMax / 2 + 1, AlignUp(size_t{1}, kSizeTMax / 2 + 1));
59 }
60
TEST(BitsTestPA,AlignUpPointer)61 TEST(BitsTestPA, AlignUpPointer) {
62 static constexpr uintptr_t kUintPtrTMax =
63 std::numeric_limits<uintptr_t>::max();
64 EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
65 AlignUp(reinterpret_cast<uint8_t*>(0), 4));
66 EXPECT_EQ(reinterpret_cast<uint8_t*>(4),
67 AlignUp(reinterpret_cast<uint8_t*>(1), 4));
68 EXPECT_EQ(reinterpret_cast<uint8_t*>(4096),
69 AlignUp(reinterpret_cast<uint8_t*>(1), 4096));
70 EXPECT_EQ(reinterpret_cast<uint8_t*>(4096),
71 AlignUp(reinterpret_cast<uint8_t*>(4096), 4096));
72 EXPECT_EQ(reinterpret_cast<uint8_t*>(4096),
73 AlignUp(reinterpret_cast<uint8_t*>(4095), 4096));
74 EXPECT_EQ(reinterpret_cast<uint8_t*>(8192),
75 AlignUp(reinterpret_cast<uint8_t*>(4097), 4096));
76 EXPECT_EQ(reinterpret_cast<uint8_t*>(kUintPtrTMax - 31),
77 AlignUp(reinterpret_cast<uint8_t*>(kUintPtrTMax - 62), 32));
78 EXPECT_EQ(reinterpret_cast<uint8_t*>(kUintPtrTMax / 2 + 1),
79 AlignUp(reinterpret_cast<uint8_t*>(1), kUintPtrTMax / 2 + 1));
80 }
81
TEST(BitsTestPA,AlignDown)82 TEST(BitsTestPA, AlignDown) {
83 static constexpr size_t kSizeTMax = std::numeric_limits<size_t>::max();
84 EXPECT_EQ(0u, AlignDown(0u, 4u));
85 EXPECT_EQ(0u, AlignDown(1u, 4u));
86 EXPECT_EQ(0u, AlignDown(1u, 4096u));
87 EXPECT_EQ(4096u, AlignDown(4096u, 4096u));
88 EXPECT_EQ(0u, AlignDown(4095u, 4096u));
89 EXPECT_EQ(4096u, AlignDown(4097u, 4096u));
90 EXPECT_EQ(kSizeTMax - 63, AlignDown(kSizeTMax - 62, size_t{32}));
91 EXPECT_EQ(kSizeTMax - 31, AlignDown(kSizeTMax, size_t{32}));
92 EXPECT_EQ(0ul, AlignDown(size_t{1}, kSizeTMax / 2 + 1));
93 }
94
TEST(BitsTestPA,AlignDownPointer)95 TEST(BitsTestPA, AlignDownPointer) {
96 static constexpr uintptr_t kUintPtrTMax =
97 std::numeric_limits<uintptr_t>::max();
98 EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
99 AlignDown(reinterpret_cast<uint8_t*>(0), 4));
100 EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
101 AlignDown(reinterpret_cast<uint8_t*>(1), 4));
102 EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
103 AlignDown(reinterpret_cast<uint8_t*>(1), 4096));
104 EXPECT_EQ(reinterpret_cast<uint8_t*>(4096),
105 AlignDown(reinterpret_cast<uint8_t*>(4096), 4096));
106 EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
107 AlignDown(reinterpret_cast<uint8_t*>(4095), 4096));
108 EXPECT_EQ(reinterpret_cast<uint8_t*>(4096),
109 AlignDown(reinterpret_cast<uint8_t*>(4097), 4096));
110 EXPECT_EQ(reinterpret_cast<uint8_t*>(kUintPtrTMax - 63),
111 AlignDown(reinterpret_cast<uint8_t*>(kUintPtrTMax - 62), 32));
112 EXPECT_EQ(reinterpret_cast<uint8_t*>(kUintPtrTMax - 31),
113 AlignDown(reinterpret_cast<uint8_t*>(kUintPtrTMax), 32));
114 EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
115 AlignDown(reinterpret_cast<uint8_t*>(1), kUintPtrTMax / 2 + 1));
116 }
117
TEST(BitsTestPA,LeftMostBit)118 TEST(BitsTestPA, LeftMostBit) {
119 // Construction of a signed type from an unsigned one of the same width
120 // preserves all bits. Explicitly confirming this behavior here to illustrate
121 // correctness of reusing unsigned literals to test behavior of signed types.
122 // Using signed literals does not work with EXPECT_EQ.
123 static_assert(
124 static_cast<int64_t>(0xFFFFFFFFFFFFFFFFu) == 0xFFFFFFFFFFFFFFFFl,
125 "Comparing signed with unsigned literals compares bits.");
126 static_assert((0xFFFFFFFFFFFFFFFFu ^ 0xFFFFFFFFFFFFFFFFl) == 0,
127 "Signed and unsigned literals have the same bits set");
128
129 uint64_t unsigned_long_long_value = 0x8000000000000000u;
130 EXPECT_EQ(LeftmostBit<uint64_t>(), unsigned_long_long_value);
131 EXPECT_EQ(LeftmostBit<int64_t>(), int64_t(unsigned_long_long_value));
132
133 uint32_t unsigned_long_value = 0x80000000u;
134 EXPECT_EQ(LeftmostBit<uint32_t>(), unsigned_long_value);
135 EXPECT_EQ(LeftmostBit<int32_t>(), int32_t(unsigned_long_value));
136
137 uint16_t unsigned_short_value = 0x8000u;
138 EXPECT_EQ(LeftmostBit<uint16_t>(), unsigned_short_value);
139 EXPECT_EQ(LeftmostBit<int16_t>(), int16_t(unsigned_short_value));
140
141 uint8_t unsigned_byte_value = 0x80u;
142 EXPECT_EQ(LeftmostBit<uint8_t>(), unsigned_byte_value);
143 EXPECT_EQ(LeftmostBit<int8_t>(), int8_t(unsigned_byte_value));
144 }
145
146 } // namespace partition_alloc::internal::base::bits
147