folly/test/BitsTest.cpp

   1 /*
   2  * Copyright 2017 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 <folly/Bits.h>
  20
  21 #include <random>
  22
  23 #include <folly/portability/GTest.h>
  24
  25 using namespace folly;
  26
  27 // Test constexpr-ness.
  28 #if !defined(__clang__) && !defined(_MSC_VER)
  29 static_assert(findFirstSet(2u) == 2, "findFirstSet");
  30 static_assert(findLastSet(2u) == 2, "findLastSet");
  31 static_assert(nextPowTwo(2u) == 2, "nextPowTwo");
  32 #endif
  33
  34 #ifndef __clang__
  35 static_assert(isPowTwo(2u), "isPowTwo");
  36 #endif
  37
  38 namespace {
  39
  40 template <class INT>
  41 void testFFS() {
  42   EXPECT_EQ(0, findFirstSet(static_cast<INT>(0)));
  43   size_t bits = std::numeric_limits<
  44     typename std::make_unsigned<INT>::type>::digits;
  45   for (size_t i = 0; i < bits; i++) {
  46     INT v = (static_cast<INT>(1) << (bits - 1)) |
  47             (static_cast<INT>(1) << i);
  48     EXPECT_EQ(i+1, findFirstSet(v));
  49   }
  50 }
  51
  52 template <class INT>
  53 void testFLS() {
  54   typedef typename std::make_unsigned<INT>::type UINT_T;
  55   EXPECT_EQ(0, findLastSet(static_cast<INT>(0)));
  56   size_t bits = std::numeric_limits<UINT_T>::digits;
  57   for (size_t i = 0; i < bits; i++) {
  58     INT v1 = static_cast<UINT_T>(1) << i;
  59     EXPECT_EQ(i + 1, findLastSet(v1));
  60
  61     INT v2 = (static_cast<UINT_T>(1) << i) - 1;
  62     EXPECT_EQ(i, findLastSet(v2));
  63   }
  64 }
  65
  66 }  // namespace
  67
  68 TEST(Bits, FindFirstSet) {
  69   testFFS<char>();
  70   testFFS<signed char>();
  71   testFFS<unsigned char>();
  72   testFFS<short>();
  73   testFFS<unsigned short>();
  74   testFFS<int>();
  75   testFFS<unsigned int>();
  76   testFFS<long>();
  77   testFFS<unsigned long>();
  78   testFFS<long long>();
  79   testFFS<unsigned long long>();
  80 }
  81
  82 TEST(Bits, FindLastSet) {
  83   testFLS<char>();
  84   testFLS<signed char>();
  85   testFLS<unsigned char>();
  86   testFLS<short>();
  87   testFLS<unsigned short>();
  88   testFLS<int>();
  89   testFLS<unsigned int>();
  90   testFLS<long>();
  91   testFLS<unsigned long>();
  92   testFLS<long long>();
  93   testFLS<unsigned long long>();
  94 }
  95
  96 TEST(Bits, nextPowTwoClz) {
  97   EXPECT_EQ(1, nextPowTwo(0u));
  98   EXPECT_EQ(1, nextPowTwo(1u));
  99   EXPECT_EQ(2, nextPowTwo(2u));
 100   EXPECT_EQ(4, nextPowTwo(3u));
 101   EXPECT_EQ(4, nextPowTwo(4u));
 102   EXPECT_EQ(8, nextPowTwo(5u));
 103   EXPECT_EQ(8, nextPowTwo(6u));
 104   EXPECT_EQ(8, nextPowTwo(7u));
 105   EXPECT_EQ(8, nextPowTwo(8u));
 106   EXPECT_EQ(16, nextPowTwo(9u));
 107   EXPECT_EQ(16, nextPowTwo(13u));
 108   EXPECT_EQ(16, nextPowTwo(16u));
 109   EXPECT_EQ(512, nextPowTwo(510u));
 110   EXPECT_EQ(512, nextPowTwo(511u));
 111   EXPECT_EQ(512, nextPowTwo(512u));
 112   EXPECT_EQ(1024, nextPowTwo(513u));
 113   EXPECT_EQ(1024, nextPowTwo(777u));
 114   EXPECT_EQ(1ul << 31, nextPowTwo((1ul << 31) - 1));
 115   EXPECT_EQ(1ull << 32, nextPowTwo((1ull << 32) - 1));
 116   EXPECT_EQ(1ull << 63, nextPowTwo((1ull << 62) + 1));
 117 }
 118
 119 TEST(Bits, prevPowTwoClz) {
 120   EXPECT_EQ(0, prevPowTwo(0u));
 121   EXPECT_EQ(1, prevPowTwo(1u));
 122   EXPECT_EQ(2, prevPowTwo(2u));
 123   EXPECT_EQ(2, prevPowTwo(3u));
 124   EXPECT_EQ(4, prevPowTwo(4u));
 125   EXPECT_EQ(4, prevPowTwo(5u));
 126   EXPECT_EQ(4, prevPowTwo(6u));
 127   EXPECT_EQ(4, prevPowTwo(7u));
 128   EXPECT_EQ(8, prevPowTwo(8u));
 129   EXPECT_EQ(8, prevPowTwo(9u));
 130   EXPECT_EQ(8, prevPowTwo(13u));
 131   EXPECT_EQ(16, prevPowTwo(16u));
 132   EXPECT_EQ(256, prevPowTwo(510u));
 133   EXPECT_EQ(256, prevPowTwo(511u));
 134   EXPECT_EQ(512, prevPowTwo(512u));
 135   EXPECT_EQ(512, prevPowTwo(513u));
 136   EXPECT_EQ(512, prevPowTwo(777u));
 137   EXPECT_EQ(1ul << 30, prevPowTwo((1ul << 31) - 1));
 138   EXPECT_EQ(1ull << 31, prevPowTwo((1ull << 32) - 1));
 139   EXPECT_EQ(1ull << 62, prevPowTwo((1ull << 62) + 1));
 140 }
 141
 142 TEST(Bits, isPowTwo) {
 143   EXPECT_FALSE(isPowTwo(0u));
 144   EXPECT_TRUE(isPowTwo(1ul));
 145   EXPECT_TRUE(isPowTwo(2ull));
 146   EXPECT_FALSE(isPowTwo(3ul));
 147   EXPECT_TRUE(isPowTwo(4ul));
 148   EXPECT_FALSE(isPowTwo(5ul));
 149   EXPECT_TRUE(isPowTwo(8ul));
 150   EXPECT_FALSE(isPowTwo(15u));
 151   EXPECT_TRUE(isPowTwo(16u));
 152   EXPECT_FALSE(isPowTwo(17u));
 153   EXPECT_FALSE(isPowTwo(511ul));
 154   EXPECT_TRUE(isPowTwo(512ul));
 155   EXPECT_FALSE(isPowTwo(513ul));
 156   EXPECT_FALSE(isPowTwo((1ul<<31) - 1));
 157   EXPECT_TRUE(isPowTwo(1ul<<31));
 158   EXPECT_FALSE(isPowTwo((1ul<<31) + 1));
 159   EXPECT_FALSE(isPowTwo((1ull<<63) - 1));
 160   EXPECT_TRUE(isPowTwo(1ull<<63));
 161   EXPECT_FALSE(isPowTwo((1ull<<63) + 1));
 162 }
 163
 164 TEST(Bits, popcount) {
 165   EXPECT_EQ(0, popcount(0U));
 166   EXPECT_EQ(1, popcount(1U));
 167   EXPECT_EQ(32, popcount(uint32_t(-1)));
 168   EXPECT_EQ(64, popcount(uint64_t(-1)));
 169 }
 170
 171 TEST(Bits, Endian_swap_uint) {
 172   EXPECT_EQ(uint8_t(0xda), Endian::swap(uint8_t(0xda)));
 173   EXPECT_EQ(uint16_t(0x4175), Endian::swap(uint16_t(0x7541)));
 174   EXPECT_EQ(uint32_t(0x42efb918), Endian::swap(uint32_t(0x18b9ef42)));
 175   EXPECT_EQ(
 176       uint64_t(0xa244f5e862c71d8a), Endian::swap(uint64_t(0x8a1dc762e8f544a2)));
 177 }
 178
 179 TEST(Bits, Endian_swap_real) {
 180   std::mt19937_64 rng;
 181   auto f = std::uniform_real_distribution<float>()(rng);
 182   EXPECT_NE(f, Endian::swap(f));
 183   EXPECT_EQ(f, Endian::swap(Endian::swap(f)));
 184   auto d = std::uniform_real_distribution<double>()(rng);
 185   EXPECT_NE(d, Endian::swap(d));
 186   EXPECT_EQ(d, Endian::swap(Endian::swap(d)));
 187 }