2 * Copyright 2016 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/Bits.h>
21 #include <folly/portability/GTest.h>
23 using namespace folly;
25 // Test constexpr-ness.
26 #if !defined(__clang__) && !defined(_MSC_VER)
27 static_assert(findFirstSet(2u) == 2, "findFirstSet");
28 static_assert(findLastSet(2u) == 2, "findLastSet");
29 static_assert(nextPowTwo(2u) == 2, "nextPowTwo");
33 static_assert(isPowTwo(2u), "isPowTwo");
40 EXPECT_EQ(0, findFirstSet(static_cast<INT>(0)));
41 size_t bits = std::numeric_limits<
42 typename std::make_unsigned<INT>::type>::digits;
43 for (size_t i = 0; i < bits; i++) {
44 INT v = (static_cast<INT>(1) << (bits - 1)) |
45 (static_cast<INT>(1) << i);
46 EXPECT_EQ(i+1, findFirstSet(v));
52 typedef typename std::make_unsigned<INT>::type UINT;
53 EXPECT_EQ(0, findLastSet(static_cast<INT>(0)));
54 size_t bits = std::numeric_limits<UINT>::digits;
55 for (size_t i = 0; i < bits; i++) {
56 INT v1 = static_cast<UINT>(1) << i;
57 EXPECT_EQ(i + 1, findLastSet(v1));
59 INT v2 = (static_cast<UINT>(1) << i) - 1;
60 EXPECT_EQ(i, findLastSet(v2));
66 TEST(Bits, FindFirstSet) {
68 testFFS<signed char>();
69 testFFS<unsigned char>();
71 testFFS<unsigned short>();
73 testFFS<unsigned int>();
75 testFFS<unsigned long>();
77 testFFS<unsigned long long>();
80 TEST(Bits, FindLastSet) {
82 testFLS<signed char>();
83 testFLS<unsigned char>();
85 testFLS<unsigned short>();
87 testFLS<unsigned int>();
89 testFLS<unsigned long>();
91 testFLS<unsigned long long>();
94 TEST(Bits, nextPowTwoClz) {
95 EXPECT_EQ(1, nextPowTwo(0u));
96 EXPECT_EQ(1, nextPowTwo(1u));
97 EXPECT_EQ(2, nextPowTwo(2u));
98 EXPECT_EQ(4, nextPowTwo(3u));
99 EXPECT_EQ(4, nextPowTwo(4u));
100 EXPECT_EQ(8, nextPowTwo(5u));
101 EXPECT_EQ(8, nextPowTwo(6u));
102 EXPECT_EQ(8, nextPowTwo(7u));
103 EXPECT_EQ(8, nextPowTwo(8u));
104 EXPECT_EQ(16, nextPowTwo(9u));
105 EXPECT_EQ(16, nextPowTwo(13u));
106 EXPECT_EQ(16, nextPowTwo(16u));
107 EXPECT_EQ(512, nextPowTwo(510u));
108 EXPECT_EQ(512, nextPowTwo(511u));
109 EXPECT_EQ(512, nextPowTwo(512u));
110 EXPECT_EQ(1024, nextPowTwo(513u));
111 EXPECT_EQ(1024, nextPowTwo(777u));
112 EXPECT_EQ(1ul << 31, nextPowTwo((1ul << 31) - 1));
113 EXPECT_EQ(1ull << 32, nextPowTwo((1ull << 32) - 1));
114 EXPECT_EQ(1ull << 63, nextPowTwo((1ull << 62) + 1));
117 TEST(Bits, prevPowTwoClz) {
118 EXPECT_EQ(0, prevPowTwo(0u));
119 EXPECT_EQ(1, prevPowTwo(1u));
120 EXPECT_EQ(2, prevPowTwo(2u));
121 EXPECT_EQ(2, prevPowTwo(3u));
122 EXPECT_EQ(4, prevPowTwo(4u));
123 EXPECT_EQ(4, prevPowTwo(5u));
124 EXPECT_EQ(4, prevPowTwo(6u));
125 EXPECT_EQ(4, prevPowTwo(7u));
126 EXPECT_EQ(8, prevPowTwo(8u));
127 EXPECT_EQ(8, prevPowTwo(9u));
128 EXPECT_EQ(8, prevPowTwo(13u));
129 EXPECT_EQ(16, prevPowTwo(16u));
130 EXPECT_EQ(256, prevPowTwo(510u));
131 EXPECT_EQ(256, prevPowTwo(511u));
132 EXPECT_EQ(512, prevPowTwo(512u));
133 EXPECT_EQ(512, prevPowTwo(513u));
134 EXPECT_EQ(512, prevPowTwo(777u));
135 EXPECT_EQ(1ul << 30, prevPowTwo((1ul << 31) - 1));
136 EXPECT_EQ(1ull << 31, prevPowTwo((1ull << 32) - 1));
137 EXPECT_EQ(1ull << 62, prevPowTwo((1ull << 62) + 1));
140 TEST(Bits, isPowTwo) {
141 EXPECT_FALSE(isPowTwo(0u));
142 EXPECT_TRUE(isPowTwo(1ul));
143 EXPECT_TRUE(isPowTwo(2ull));
144 EXPECT_FALSE(isPowTwo(3ul));
145 EXPECT_TRUE(isPowTwo(4ul));
146 EXPECT_FALSE(isPowTwo(5ul));
147 EXPECT_TRUE(isPowTwo(8ul));
148 EXPECT_FALSE(isPowTwo(15u));
149 EXPECT_TRUE(isPowTwo(16u));
150 EXPECT_FALSE(isPowTwo(17u));
151 EXPECT_FALSE(isPowTwo(511ul));
152 EXPECT_TRUE(isPowTwo(512ul));
153 EXPECT_FALSE(isPowTwo(513ul));
154 EXPECT_FALSE(isPowTwo((1ul<<31) - 1));
155 EXPECT_TRUE(isPowTwo(1ul<<31));
156 EXPECT_FALSE(isPowTwo((1ul<<31) + 1));
157 EXPECT_FALSE(isPowTwo((1ull<<63) - 1));
158 EXPECT_TRUE(isPowTwo(1ull<<63));
159 EXPECT_FALSE(isPowTwo((1ull<<63) + 1));
162 TEST(Bits, popcount) {
163 EXPECT_EQ(0, popcount(0U));
164 EXPECT_EQ(1, popcount(1U));
165 EXPECT_EQ(32, popcount(uint32_t(-1)));
166 EXPECT_EQ(64, popcount(uint64_t(-1)));