2 * Copyright 2017 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 // @author Tudor Bosman (tudorb@fb.com)
19 #include <folly/lang/Bits.h>
21 #include <folly/Random.h>
24 #include <folly/portability/GTest.h>
26 using namespace folly;
28 // Test constexpr-ness.
29 #if !defined(__clang__) && !defined(_MSC_VER)
30 static_assert(findFirstSet(2u) == 2, "findFirstSet");
31 static_assert(findLastSet(2u) == 2, "findLastSet");
32 static_assert(nextPowTwo(2u) == 2, "nextPowTwo");
36 static_assert(isPowTwo(2u), "isPowTwo");
43 EXPECT_EQ(0, findFirstSet(static_cast<INT>(0)));
44 size_t bits = std::numeric_limits<
45 typename std::make_unsigned<INT>::type>::digits;
46 for (size_t i = 0; i < bits; i++) {
47 INT v = (static_cast<INT>(1) << (bits - 1)) |
48 (static_cast<INT>(1) << i);
49 EXPECT_EQ(i+1, findFirstSet(v));
55 typedef typename std::make_unsigned<INT>::type UINT_T;
56 EXPECT_EQ(0, findLastSet(static_cast<INT>(0)));
57 size_t bits = std::numeric_limits<UINT_T>::digits;
58 for (size_t i = 0; i < bits; i++) {
59 INT v1 = static_cast<UINT_T>(1) << i;
60 EXPECT_EQ(i + 1, findLastSet(v1));
62 INT v2 = (static_cast<UINT_T>(1) << i) - 1;
63 EXPECT_EQ(i, findLastSet(v2));
69 TEST(Bits, FindFirstSet) {
71 testFFS<signed char>();
72 testFFS<unsigned char>();
74 testFFS<unsigned short>();
76 testFFS<unsigned int>();
78 testFFS<unsigned long>();
80 testFFS<unsigned long long>();
83 TEST(Bits, FindLastSet) {
85 testFLS<signed char>();
86 testFLS<unsigned char>();
88 testFLS<unsigned short>();
90 testFLS<unsigned int>();
92 testFLS<unsigned long>();
94 testFLS<unsigned long long>();
97 TEST(Bits, nextPowTwoClz) {
98 EXPECT_EQ(1, nextPowTwo(0u));
99 EXPECT_EQ(1, nextPowTwo(1u));
100 EXPECT_EQ(2, nextPowTwo(2u));
101 EXPECT_EQ(4, nextPowTwo(3u));
102 EXPECT_EQ(4, nextPowTwo(4u));
103 EXPECT_EQ(8, nextPowTwo(5u));
104 EXPECT_EQ(8, nextPowTwo(6u));
105 EXPECT_EQ(8, nextPowTwo(7u));
106 EXPECT_EQ(8, nextPowTwo(8u));
107 EXPECT_EQ(16, nextPowTwo(9u));
108 EXPECT_EQ(16, nextPowTwo(13u));
109 EXPECT_EQ(16, nextPowTwo(16u));
110 EXPECT_EQ(512, nextPowTwo(510u));
111 EXPECT_EQ(512, nextPowTwo(511u));
112 EXPECT_EQ(512, nextPowTwo(512u));
113 EXPECT_EQ(1024, nextPowTwo(513u));
114 EXPECT_EQ(1024, nextPowTwo(777u));
115 EXPECT_EQ(1ul << 31, nextPowTwo((1ul << 31) - 1));
116 EXPECT_EQ(1ull << 32, nextPowTwo((1ull << 32) - 1));
117 EXPECT_EQ(1ull << 63, nextPowTwo((1ull << 62) + 1));
120 TEST(Bits, prevPowTwoClz) {
121 EXPECT_EQ(0, prevPowTwo(0u));
122 EXPECT_EQ(1, prevPowTwo(1u));
123 EXPECT_EQ(2, prevPowTwo(2u));
124 EXPECT_EQ(2, prevPowTwo(3u));
125 EXPECT_EQ(4, prevPowTwo(4u));
126 EXPECT_EQ(4, prevPowTwo(5u));
127 EXPECT_EQ(4, prevPowTwo(6u));
128 EXPECT_EQ(4, prevPowTwo(7u));
129 EXPECT_EQ(8, prevPowTwo(8u));
130 EXPECT_EQ(8, prevPowTwo(9u));
131 EXPECT_EQ(8, prevPowTwo(13u));
132 EXPECT_EQ(16, prevPowTwo(16u));
133 EXPECT_EQ(256, prevPowTwo(510u));
134 EXPECT_EQ(256, prevPowTwo(511u));
135 EXPECT_EQ(512, prevPowTwo(512u));
136 EXPECT_EQ(512, prevPowTwo(513u));
137 EXPECT_EQ(512, prevPowTwo(777u));
138 EXPECT_EQ(1ul << 30, prevPowTwo((1ul << 31) - 1));
139 EXPECT_EQ(1ull << 31, prevPowTwo((1ull << 32) - 1));
140 EXPECT_EQ(1ull << 62, prevPowTwo((1ull << 62) + 1));
143 TEST(Bits, isPowTwo) {
144 EXPECT_FALSE(isPowTwo(0u));
145 EXPECT_TRUE(isPowTwo(1ul));
146 EXPECT_TRUE(isPowTwo(2ull));
147 EXPECT_FALSE(isPowTwo(3ul));
148 EXPECT_TRUE(isPowTwo(4ul));
149 EXPECT_FALSE(isPowTwo(5ul));
150 EXPECT_TRUE(isPowTwo(8ul));
151 EXPECT_FALSE(isPowTwo(15u));
152 EXPECT_TRUE(isPowTwo(16u));
153 EXPECT_FALSE(isPowTwo(17u));
154 EXPECT_FALSE(isPowTwo(511ul));
155 EXPECT_TRUE(isPowTwo(512ul));
156 EXPECT_FALSE(isPowTwo(513ul));
157 EXPECT_FALSE(isPowTwo((1ul<<31) - 1));
158 EXPECT_TRUE(isPowTwo(1ul<<31));
159 EXPECT_FALSE(isPowTwo((1ul<<31) + 1));
160 EXPECT_FALSE(isPowTwo((1ull<<63) - 1));
161 EXPECT_TRUE(isPowTwo(1ull<<63));
162 EXPECT_FALSE(isPowTwo((1ull<<63) + 1));
165 TEST(Bits, popcount) {
166 EXPECT_EQ(0, popcount(0U));
167 EXPECT_EQ(1, popcount(1U));
168 EXPECT_EQ(32, popcount(uint32_t(-1)));
169 EXPECT_EQ(64, popcount(uint64_t(-1)));
172 TEST(Bits, Endian_swap_uint) {
173 EXPECT_EQ(uint8_t(0xda), Endian::swap(uint8_t(0xda)));
174 EXPECT_EQ(uint16_t(0x4175), Endian::swap(uint16_t(0x7541)));
175 EXPECT_EQ(uint32_t(0x42efb918), Endian::swap(uint32_t(0x18b9ef42)));
177 uint64_t(0xa244f5e862c71d8a), Endian::swap(uint64_t(0x8a1dc762e8f544a2)));
180 TEST(Bits, Endian_swap_real) {
182 auto f = std::uniform_real_distribution<float>()(rng);
183 EXPECT_NE(f, Endian::swap(f));
184 EXPECT_EQ(f, Endian::swap(Endian::swap(f)));
185 auto d = std::uniform_real_distribution<double>()(rng);
186 EXPECT_NE(d, Endian::swap(d));
187 EXPECT_EQ(d, Endian::swap(Endian::swap(d)));
190 uint64_t reverse_simple(uint64_t v) {
193 for (int i = 0; i < 64; i++) {
201 TEST(Bits, BitReverse) {
202 EXPECT_EQ(folly::bitReverse<uint8_t>(0), 0);
203 EXPECT_EQ(folly::bitReverse<uint8_t>(1), 128);
204 for (int i = 0; i < 100; i++) {
205 uint64_t v = folly::Random::rand64();
206 EXPECT_EQ(folly::bitReverse(v), reverse_simple(v));
207 uint32_t b = folly::Random::rand32();
208 EXPECT_EQ(folly::bitReverse(b), reverse_simple(b) >> 32);