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.
5 // This file contains the unit tests for the bit utilities.
8 #include "build/build_config.h"
14 #include "testing/gtest/include/gtest/gtest.h"
19 TEST(BitsTest, Log2Floor) {
20 EXPECT_EQ(-1, Log2Floor(0));
21 EXPECT_EQ(0, Log2Floor(1));
22 EXPECT_EQ(1, Log2Floor(2));
23 EXPECT_EQ(1, Log2Floor(3));
24 EXPECT_EQ(2, Log2Floor(4));
25 for (int i = 3; i < 31; ++i) {
26 unsigned int value = 1U << i;
27 EXPECT_EQ(i, Log2Floor(value));
28 EXPECT_EQ(i, Log2Floor(value + 1));
29 EXPECT_EQ(i, Log2Floor(value + 2));
30 EXPECT_EQ(i - 1, Log2Floor(value - 1));
31 EXPECT_EQ(i - 1, Log2Floor(value - 2));
33 EXPECT_EQ(31, Log2Floor(0xffffffffU));
36 TEST(BitsTest, Log2Ceiling) {
37 EXPECT_EQ(-1, Log2Ceiling(0));
38 EXPECT_EQ(0, Log2Ceiling(1));
39 EXPECT_EQ(1, Log2Ceiling(2));
40 EXPECT_EQ(2, Log2Ceiling(3));
41 EXPECT_EQ(2, Log2Ceiling(4));
42 for (int i = 3; i < 31; ++i) {
43 unsigned int value = 1U << i;
44 EXPECT_EQ(i, Log2Ceiling(value));
45 EXPECT_EQ(i + 1, Log2Ceiling(value + 1));
46 EXPECT_EQ(i + 1, Log2Ceiling(value + 2));
47 EXPECT_EQ(i, Log2Ceiling(value - 1));
48 EXPECT_EQ(i, Log2Ceiling(value - 2));
50 EXPECT_EQ(32, Log2Ceiling(0xffffffffU));
53 TEST(BitsTest, AlignUp) {
54 static constexpr size_t kSizeTMax = std::numeric_limits<size_t>::max();
55 EXPECT_EQ(0, AlignUp(0, 4));
56 EXPECT_EQ(4, AlignUp(1, 4));
57 EXPECT_EQ(4096, AlignUp(1, 4096));
58 EXPECT_EQ(4096, AlignUp(4096, 4096));
59 EXPECT_EQ(4096, AlignUp(4095, 4096));
60 EXPECT_EQ(8192, AlignUp(4097, 4096));
61 EXPECT_EQ(kSizeTMax - 31, AlignUp(kSizeTMax - 62, size_t{32}));
62 EXPECT_EQ(kSizeTMax / 2 + 1, AlignUp(size_t{1}, kSizeTMax / 2 + 1));
65 TEST(BitsTest, AlignUpPointer) {
66 static constexpr uintptr_t kUintPtrTMax =
67 std::numeric_limits<uintptr_t>::max();
68 EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
69 AlignUp(reinterpret_cast<uint8_t*>(0), 4));
70 EXPECT_EQ(reinterpret_cast<uint8_t*>(4),
71 AlignUp(reinterpret_cast<uint8_t*>(1), 4));
72 EXPECT_EQ(reinterpret_cast<uint8_t*>(4096),
73 AlignUp(reinterpret_cast<uint8_t*>(1), 4096));
74 EXPECT_EQ(reinterpret_cast<uint8_t*>(4096),
75 AlignUp(reinterpret_cast<uint8_t*>(4096), 4096));
76 EXPECT_EQ(reinterpret_cast<uint8_t*>(4096),
77 AlignUp(reinterpret_cast<uint8_t*>(4095), 4096));
78 EXPECT_EQ(reinterpret_cast<uint8_t*>(8192),
79 AlignUp(reinterpret_cast<uint8_t*>(4097), 4096));
80 EXPECT_EQ(reinterpret_cast<uint8_t*>(kUintPtrTMax - 31),
81 AlignUp(reinterpret_cast<uint8_t*>(kUintPtrTMax - 62), 32));
82 EXPECT_EQ(reinterpret_cast<uint8_t*>(kUintPtrTMax / 2 + 1),
83 AlignUp(reinterpret_cast<uint8_t*>(1), kUintPtrTMax / 2 + 1));
86 TEST(BitsTest, AlignDown) {
87 static constexpr size_t kSizeTMax = std::numeric_limits<size_t>::max();
88 EXPECT_EQ(0, AlignDown(0, 4));
89 EXPECT_EQ(0, AlignDown(1, 4));
90 EXPECT_EQ(0, AlignDown(1, 4096));
91 EXPECT_EQ(4096, AlignDown(4096, 4096));
92 EXPECT_EQ(0, AlignDown(4095, 4096));
93 EXPECT_EQ(4096, AlignDown(4097, 4096));
94 EXPECT_EQ(kSizeTMax - 63, AlignDown(kSizeTMax - 62, size_t{32}));
95 EXPECT_EQ(kSizeTMax - 31, AlignDown(kSizeTMax, size_t{32}));
96 EXPECT_EQ(0ul, AlignDown(size_t{1}, kSizeTMax / 2 + 1));
99 TEST(BitsTest, AlignDownPointer) {
100 static constexpr uintptr_t kUintPtrTMax =
101 std::numeric_limits<uintptr_t>::max();
102 EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
103 AlignDown(reinterpret_cast<uint8_t*>(0), 4));
104 EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
105 AlignDown(reinterpret_cast<uint8_t*>(1), 4));
106 EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
107 AlignDown(reinterpret_cast<uint8_t*>(1), 4096));
108 EXPECT_EQ(reinterpret_cast<uint8_t*>(4096),
109 AlignDown(reinterpret_cast<uint8_t*>(4096), 4096));
110 EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
111 AlignDown(reinterpret_cast<uint8_t*>(4095), 4096));
112 EXPECT_EQ(reinterpret_cast<uint8_t*>(4096),
113 AlignDown(reinterpret_cast<uint8_t*>(4097), 4096));
114 EXPECT_EQ(reinterpret_cast<uint8_t*>(kUintPtrTMax - 63),
115 AlignDown(reinterpret_cast<uint8_t*>(kUintPtrTMax - 62), 32));
116 EXPECT_EQ(reinterpret_cast<uint8_t*>(kUintPtrTMax - 31),
117 AlignDown(reinterpret_cast<uint8_t*>(kUintPtrTMax), 32));
118 EXPECT_EQ(reinterpret_cast<uint8_t*>(0),
119 AlignDown(reinterpret_cast<uint8_t*>(1), kUintPtrTMax / 2 + 1));
122 TEST(BitsTest, CountLeadingZeroBits8) {
123 EXPECT_EQ(8, CountLeadingZeroBits(uint8_t{0}));
124 EXPECT_EQ(7, CountLeadingZeroBits(uint8_t{1}));
125 for (int shift = 0; shift <= 7; ++shift) {
127 CountLeadingZeroBits(static_cast<uint8_t>(1 << shift)));
129 EXPECT_EQ(4, CountLeadingZeroBits(uint8_t{0x0f}));
132 TEST(BitsTest, CountLeadingZeroBits16) {
133 EXPECT_EQ(16, CountLeadingZeroBits(uint16_t{0}));
134 EXPECT_EQ(15, CountLeadingZeroBits(uint16_t{1}));
135 for (int shift = 0; shift <= 15; ++shift) {
136 EXPECT_EQ(15 - shift,
137 CountLeadingZeroBits(static_cast<uint16_t>(1 << shift)));
139 EXPECT_EQ(4, CountLeadingZeroBits(uint16_t{0x0f0f}));
142 TEST(BitsTest, CountLeadingZeroBits32) {
143 EXPECT_EQ(32, CountLeadingZeroBits(uint32_t{0}));
144 EXPECT_EQ(31, CountLeadingZeroBits(uint32_t{1}));
145 for (int shift = 0; shift <= 31; ++shift) {
146 EXPECT_EQ(31 - shift, CountLeadingZeroBits(uint32_t{1} << shift));
148 EXPECT_EQ(4, CountLeadingZeroBits(uint32_t{0x0f0f0f0f}));
151 TEST(BitsTest, CountTrailingZeroBits8) {
152 EXPECT_EQ(8, CountTrailingZeroBits(uint8_t{0}));
153 EXPECT_EQ(7, CountTrailingZeroBits(uint8_t{128}));
154 for (int shift = 0; shift <= 7; ++shift) {
155 EXPECT_EQ(shift, CountTrailingZeroBits(static_cast<uint8_t>(1 << shift)));
157 EXPECT_EQ(4, CountTrailingZeroBits(uint8_t{0xf0}));
160 TEST(BitsTest, CountTrailingZeroBits16) {
161 EXPECT_EQ(16, CountTrailingZeroBits(uint16_t{0}));
162 EXPECT_EQ(15, CountTrailingZeroBits(uint16_t{32768}));
163 for (int shift = 0; shift <= 15; ++shift) {
164 EXPECT_EQ(shift, CountTrailingZeroBits(static_cast<uint16_t>(1 << shift)));
166 EXPECT_EQ(4, CountTrailingZeroBits(uint16_t{0xf0f0}));
169 TEST(BitsTest, CountTrailingZeroBits32) {
170 EXPECT_EQ(32, CountTrailingZeroBits(uint32_t{0}));
171 EXPECT_EQ(31, CountTrailingZeroBits(uint32_t{1} << 31));
172 for (int shift = 0; shift <= 31; ++shift) {
173 EXPECT_EQ(shift, CountTrailingZeroBits(uint32_t{1} << shift));
175 EXPECT_EQ(4, CountTrailingZeroBits(uint32_t{0xf0f0f0f0}));
178 TEST(BitsTest, CountLeadingZeroBits64) {
179 EXPECT_EQ(64, CountLeadingZeroBits(uint64_t{0}));
180 EXPECT_EQ(63, CountLeadingZeroBits(uint64_t{1}));
181 for (int shift = 0; shift <= 63; ++shift) {
182 EXPECT_EQ(63 - shift, CountLeadingZeroBits(uint64_t{1} << shift));
184 EXPECT_EQ(4, CountLeadingZeroBits(uint64_t{0x0f0f0f0f0f0f0f0f}));
187 TEST(BitsTest, CountTrailingZeroBits64) {
188 EXPECT_EQ(64, CountTrailingZeroBits(uint64_t{0}));
189 EXPECT_EQ(63, CountTrailingZeroBits(uint64_t{1} << 63));
190 for (int shift = 0; shift <= 31; ++shift) {
191 EXPECT_EQ(shift, CountTrailingZeroBits(uint64_t{1} << shift));
193 EXPECT_EQ(4, CountTrailingZeroBits(uint64_t{0xf0f0f0f0f0f0f0f0}));
196 TEST(BitsTest, CountLeadingZeroBitsSizeT) {
197 #if defined(ARCH_CPU_64_BITS)
198 EXPECT_EQ(64, CountLeadingZeroBits(size_t{0}));
199 EXPECT_EQ(63, CountLeadingZeroBits(size_t{1}));
200 EXPECT_EQ(32, CountLeadingZeroBits(size_t{1} << 31));
201 EXPECT_EQ(1, CountLeadingZeroBits(size_t{1} << 62));
202 EXPECT_EQ(0, CountLeadingZeroBits(size_t{1} << 63));
204 EXPECT_EQ(32, CountLeadingZeroBits(size_t{0}));
205 EXPECT_EQ(31, CountLeadingZeroBits(size_t{1}));
206 EXPECT_EQ(1, CountLeadingZeroBits(size_t{1} << 30));
207 EXPECT_EQ(0, CountLeadingZeroBits(size_t{1} << 31));
208 #endif // ARCH_CPU_64_BITS
211 TEST(BitsTest, CountTrailingZeroBitsSizeT) {
212 #if defined(ARCH_CPU_64_BITS)
213 EXPECT_EQ(64, CountTrailingZeroBits(size_t{0}));
214 EXPECT_EQ(63, CountTrailingZeroBits(size_t{1} << 63));
215 EXPECT_EQ(31, CountTrailingZeroBits(size_t{1} << 31));
216 EXPECT_EQ(1, CountTrailingZeroBits(size_t{2}));
217 EXPECT_EQ(0, CountTrailingZeroBits(size_t{1}));
219 EXPECT_EQ(32, CountTrailingZeroBits(size_t{0}));
220 EXPECT_EQ(31, CountTrailingZeroBits(size_t{1} << 31));
221 EXPECT_EQ(1, CountTrailingZeroBits(size_t{2}));
222 EXPECT_EQ(0, CountTrailingZeroBits(size_t{1}));
223 #endif // ARCH_CPU_64_BITS
226 TEST(BitsTest, PowerOfTwo) {
227 EXPECT_FALSE(IsPowerOfTwo(-1));
228 EXPECT_FALSE(IsPowerOfTwo(0));
229 EXPECT_TRUE(IsPowerOfTwo(1));
230 EXPECT_TRUE(IsPowerOfTwo(2));
231 // Unsigned 64 bit cases.
232 for (uint32_t i = 2; i < 64; i++) {
233 const uint64_t val = uint64_t{1} << i;
234 EXPECT_FALSE(IsPowerOfTwo(val - 1));
235 EXPECT_TRUE(IsPowerOfTwo(val));
236 EXPECT_FALSE(IsPowerOfTwo(val + 1));
238 // Signed 64 bit cases.
239 for (uint32_t i = 2; i < 63; i++) {
240 const int64_t val = int64_t{1} << i;
241 EXPECT_FALSE(IsPowerOfTwo(val - 1));
242 EXPECT_TRUE(IsPowerOfTwo(val));
243 EXPECT_FALSE(IsPowerOfTwo(val + 1));
245 // Signed integers with only the last bit set are negative, not powers of two.
246 EXPECT_FALSE(IsPowerOfTwo(int64_t{1} << 63));
249 TEST(BitsTest, LeftMostBit) {
250 // Construction of a signed type from an unsigned one of the same width
251 // preserves all bits. Explicitly confirming this behavior here to illustrate
252 // correctness of reusing unsigned literals to test behavior of signed types.
253 // Using signed literals does not work with EXPECT_EQ.
254 static_assert(int64_t(0xFFFFFFFFFFFFFFFFu) == 0xFFFFFFFFFFFFFFFFl,
255 "Comparing signed with unsigned literals compares bits.");
256 static_assert((0xFFFFFFFFFFFFFFFFu ^ 0xFFFFFFFFFFFFFFFFl) == 0,
257 "Signed and unsigned literals have the same bits set");
259 uint64_t unsigned_long_long_value = 0x8000000000000000u;
260 EXPECT_EQ(LeftmostBit<uint64_t>(), unsigned_long_long_value);
261 EXPECT_EQ(LeftmostBit<int64_t>(), int64_t(unsigned_long_long_value));
263 uint32_t unsigned_long_value = 0x80000000u;
264 EXPECT_EQ(LeftmostBit<uint32_t>(), unsigned_long_value);
265 EXPECT_EQ(LeftmostBit<int32_t>(), int32_t(unsigned_long_value));
267 uint16_t unsigned_short_value = 0x8000u;
268 EXPECT_EQ(LeftmostBit<uint16_t>(), unsigned_short_value);
269 EXPECT_EQ(LeftmostBit<int16_t>(), int16_t(unsigned_short_value));
271 uint8_t unsigned_byte_value = 0x80u;
272 EXPECT_EQ(LeftmostBit<uint8_t>(), unsigned_byte_value);
273 EXPECT_EQ(LeftmostBit<int8_t>(), int8_t(unsigned_byte_value));