1/*
2 * Copyright 2011-present Facebook, Inc.
3 *
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
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
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.
15 */
16
17// @author Tudor Bosman (tudorb@fb.com)
18
19#include <algorithm>
20#include <random>
21#include <vector>
22
23#include <folly/Random.h>
24#include <folly/lang/Bits.h>
25
26#include <folly/portability/GTest.h>
27
28using namespace folly;
29
30// Test constexpr-ness.
31#if !defined(__clang__) && !defined(_MSC_VER)
32static_assert(findFirstSet(2u) == 2, "findFirstSet");
33static_assert(findLastSet(2u) == 2, "findLastSet");
34static_assert(nextPowTwo(2u) == 2, "nextPowTwo");
35#endif
36
37#ifndef __clang__
38static_assert(isPowTwo(2u), "isPowTwo");
39#endif
40
41namespace {
42
43template <class INT>
44void testFFS() {
45 EXPECT_EQ(0, findFirstSet(static_cast<INT>(0)));
46 size_t bits =
47 std::numeric_limits<typename std::make_unsigned<INT>::type>::digits;
48 for (size_t i = 0; i < bits; i++) {
49 INT v = (static_cast<INT>(1) << (bits - 1)) | (static_cast<INT>(1) << i);
50 EXPECT_EQ(i + 1, findFirstSet(v));
51 }
52}
53
54template <class INT>
55void testFLS() {
56 typedef typename std::make_unsigned<INT>::type UINT_T;
57 EXPECT_EQ(0, findLastSet(static_cast<INT>(0)));
58 size_t bits = std::numeric_limits<UINT_T>::digits;
59 for (size_t i = 0; i < bits; i++) {
60 INT v1 = static_cast<UINT_T>(1) << i;
61 EXPECT_EQ(i + 1, findLastSet(v1));
62
63 INT v2 = (static_cast<UINT_T>(1) << i) - 1;
64 EXPECT_EQ(i, findLastSet(v2));
65 }
66}
67
68} // namespace
69
70TEST(Bits, FindFirstSet) {
71 testFFS<char>();
72 testFFS<signed char>();
73 testFFS<unsigned char>();
74 testFFS<short>();
75 testFFS<unsigned short>();
76 testFFS<int>();
77 testFFS<unsigned int>();
78 testFFS<long>();
79 testFFS<unsigned long>();
80 testFFS<long long>();
81 testFFS<unsigned long long>();
82}
83
84TEST(Bits, FindLastSet) {
85 testFLS<char>();
86 testFLS<signed char>();
87 testFLS<unsigned char>();
88 testFLS<short>();
89 testFLS<unsigned short>();
90 testFLS<int>();
91 testFLS<unsigned int>();
92 testFLS<long>();
93 testFLS<unsigned long>();
94 testFLS<long long>();
95 testFLS<unsigned long long>();
96}
97
98TEST(Bits, nextPowTwoClz) {
99 EXPECT_EQ(1, nextPowTwo(0u));
100 EXPECT_EQ(1, nextPowTwo(1u));
101 EXPECT_EQ(2, nextPowTwo(2u));
102 EXPECT_EQ(4, nextPowTwo(3u));
103 EXPECT_EQ(4, nextPowTwo(4u));
104 EXPECT_EQ(8, nextPowTwo(5u));
105 EXPECT_EQ(8, nextPowTwo(6u));
106 EXPECT_EQ(8, nextPowTwo(7u));
107 EXPECT_EQ(8, nextPowTwo(8u));
108 EXPECT_EQ(16, nextPowTwo(9u));
109 EXPECT_EQ(16, nextPowTwo(13u));
110 EXPECT_EQ(16, nextPowTwo(16u));
111 EXPECT_EQ(512, nextPowTwo(510u));
112 EXPECT_EQ(512, nextPowTwo(511u));
113 EXPECT_EQ(512, nextPowTwo(512u));
114 EXPECT_EQ(1024, nextPowTwo(513u));
115 EXPECT_EQ(1024, nextPowTwo(777u));
116 EXPECT_EQ(1ul << 31, nextPowTwo((1ul << 31) - 1));
117 EXPECT_EQ(1ull << 32, nextPowTwo((1ull << 32) - 1));
118 EXPECT_EQ(1ull << 63, nextPowTwo((1ull << 62) + 1));
119}
120
121TEST(Bits, prevPowTwoClz) {
122 EXPECT_EQ(0, prevPowTwo(0u));
123 EXPECT_EQ(1, prevPowTwo(1u));
124 EXPECT_EQ(2, prevPowTwo(2u));
125 EXPECT_EQ(2, prevPowTwo(3u));
126 EXPECT_EQ(4, prevPowTwo(4u));
127 EXPECT_EQ(4, prevPowTwo(5u));
128 EXPECT_EQ(4, prevPowTwo(6u));
129 EXPECT_EQ(4, prevPowTwo(7u));
130 EXPECT_EQ(8, prevPowTwo(8u));
131 EXPECT_EQ(8, prevPowTwo(9u));
132 EXPECT_EQ(8, prevPowTwo(13u));
133 EXPECT_EQ(16, prevPowTwo(16u));
134 EXPECT_EQ(256, prevPowTwo(510u));
135 EXPECT_EQ(256, prevPowTwo(511u));
136 EXPECT_EQ(512, prevPowTwo(512u));
137 EXPECT_EQ(512, prevPowTwo(513u));
138 EXPECT_EQ(512, prevPowTwo(777u));
139 EXPECT_EQ(1ul << 30, prevPowTwo((1ul << 31) - 1));
140 EXPECT_EQ(1ull << 31, prevPowTwo((1ull << 32) - 1));
141 EXPECT_EQ(1ull << 62, prevPowTwo((1ull << 62) + 1));
142}
143
144TEST(Bits, isPowTwo) {
145 EXPECT_FALSE(isPowTwo(0u));
146 EXPECT_TRUE(isPowTwo(1ul));
147 EXPECT_TRUE(isPowTwo(2ull));
148 EXPECT_FALSE(isPowTwo(3ul));
149 EXPECT_TRUE(isPowTwo(4ul));
150 EXPECT_FALSE(isPowTwo(5ul));
151 EXPECT_TRUE(isPowTwo(8ul));
152 EXPECT_FALSE(isPowTwo(15u));
153 EXPECT_TRUE(isPowTwo(16u));
154 EXPECT_FALSE(isPowTwo(17u));
155 EXPECT_FALSE(isPowTwo(511ul));
156 EXPECT_TRUE(isPowTwo(512ul));
157 EXPECT_FALSE(isPowTwo(513ul));
158 EXPECT_FALSE(isPowTwo((1ul << 31) - 1));
159 EXPECT_TRUE(isPowTwo(1ul << 31));
160 EXPECT_FALSE(isPowTwo((1ul << 31) + 1));
161 EXPECT_FALSE(isPowTwo((1ull << 63) - 1));
162 EXPECT_TRUE(isPowTwo(1ull << 63));
163 EXPECT_FALSE(isPowTwo((1ull << 63) + 1));
164}
165
166TEST(Bits, popcount) {
167 EXPECT_EQ(0, popcount(0U));
168 EXPECT_EQ(1, popcount(1U));
169 EXPECT_EQ(32, popcount(uint32_t(-1)));
170 EXPECT_EQ(64, popcount(uint64_t(-1)));
171}
172
173TEST(Bits, Endian_swap_uint) {
174 EXPECT_EQ(uint8_t(0xda), Endian::swap(uint8_t(0xda)));
175 EXPECT_EQ(uint16_t(0x4175), Endian::swap(uint16_t(0x7541)));
176 EXPECT_EQ(uint32_t(0x42efb918), Endian::swap(uint32_t(0x18b9ef42)));
177 EXPECT_EQ(
178 uint64_t(0xa244f5e862c71d8a), Endian::swap(uint64_t(0x8a1dc762e8f544a2)));
179}
180
181TEST(Bits, Endian_swap_real) {
182 std::mt19937_64 rng;
183 auto f = std::uniform_real_distribution<float>()(rng);
184 EXPECT_NE(f, Endian::swap(f));
185 EXPECT_EQ(f, Endian::swap(Endian::swap(f)));
186 auto d = std::uniform_real_distribution<double>()(rng);
187 EXPECT_NE(d, Endian::swap(d));
188 EXPECT_EQ(d, Endian::swap(Endian::swap(d)));
189}
190
191uint64_t reverse_simple(uint64_t v) {
192 uint64_t r = 0;
193
194 for (int i = 0; i < 64; i++) {
195 r <<= 1;
196 r |= v & 1;
197 v >>= 1;
198 }
199 return r;
200}
201
202TEST(Bits, BitReverse) {
203 EXPECT_EQ(folly::bitReverse<uint8_t>(0), 0);
204 EXPECT_EQ(folly::bitReverse<uint8_t>(1), 128);
205 for (int i = 0; i < 100; i++) {
206 uint64_t v = folly::Random::rand64();
207 EXPECT_EQ(folly::bitReverse(v), reverse_simple(v));
208 uint32_t b = folly::Random::rand32();
209 EXPECT_EQ(folly::bitReverse(b), reverse_simple(b) >> 32);
210 }
211}
212
213TEST(Bits, PartialLoadUnaligned) {
214 std::vector<char> buf(128);
215 std::generate(
216 buf.begin(), buf.end(), [] { return folly::Random::rand32(255); });
217 for (size_t l = 0; l < 8; ++l) {
218 for (size_t pos = 0; pos <= buf.size() - l; ++pos) {
219 auto p = buf.data() + pos;
220 auto x = folly::partialLoadUnaligned<uint64_t>(p, l);
221
222 uint64_t expected = 0;
223 memcpy(&expected, p, l);
224
225 EXPECT_EQ(x, expected);
226
227 if (l < 4) {
228 auto x32 = folly::partialLoadUnaligned<uint32_t>(p, l);
229 EXPECT_EQ(x32, static_cast<uint32_t>(expected));
230 }
231 }
232 }
233}
234