folly/test/BitsTest.cpp

   1 /*
   2  * Copyright 2016 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 <gtest/gtest.h>
  22
  23 using namespace folly;
  24
  25 // Test constexpr-ness.
  26 #ifndef __clang__
  27 static_assert(findFirstSet(2u) == 2, "findFirstSet");
  28 static_assert(findLastSet(2u) == 2, "findLastSet");
  29 static_assert(nextPowTwo(2u) == 2, "nextPowTwo");
  30 static_assert(isPowTwo(2u), "isPowTwo");
  31 #endif  // __clang__
  32
  33 namespace {
  34
  35 template <class INT>
  36 void testFFS() {
  37   EXPECT_EQ(0, findFirstSet(static_cast<INT>(0)));
  38   size_t bits = std::numeric_limits<
  39     typename std::make_unsigned<INT>::type>::digits;
  40   for (size_t i = 0; i < bits; i++) {
  41     INT v = (static_cast<INT>(1) << (bits - 1)) |
  42             (static_cast<INT>(1) << i);
  43     EXPECT_EQ(i+1, findFirstSet(v));
  44   }
  45 }
  46
  47 template <class INT>
  48 void testFLS() {
  49   typedef typename std::make_unsigned<INT>::type UINT;
  50   EXPECT_EQ(0, findLastSet(static_cast<INT>(0)));
  51   size_t bits = std::numeric_limits<UINT>::digits;
  52   for (size_t i = 0; i < bits; i++) {
  53     INT v1 = static_cast<UINT>(1) << i;
  54     EXPECT_EQ(i + 1, findLastSet(v1));
  55
  56     INT v2 = (static_cast<UINT>(1) << i) - 1;
  57     EXPECT_EQ(i, findLastSet(v2));
  58   }
  59 }
  60
  61 }  // namespace
  62
  63 TEST(Bits, FindFirstSet) {
  64   testFFS<char>();
  65   testFFS<signed char>();
  66   testFFS<unsigned char>();
  67   testFFS<short>();
  68   testFFS<unsigned short>();
  69   testFFS<int>();
  70   testFFS<unsigned int>();
  71   testFFS<long>();
  72   testFFS<unsigned long>();
  73   testFFS<long long>();
  74   testFFS<unsigned long long>();
  75 }
  76
  77 TEST(Bits, FindLastSet) {
  78   testFLS<char>();
  79   testFLS<signed char>();
  80   testFLS<unsigned char>();
  81   testFLS<short>();
  82   testFLS<unsigned short>();
  83   testFLS<int>();
  84   testFLS<unsigned int>();
  85   testFLS<long>();
  86   testFLS<unsigned long>();
  87   testFLS<long long>();
  88   testFLS<unsigned long long>();
  89 }
  90
  91 #define testPowTwo(nextPowTwoFunc) {                              \
  92   EXPECT_EQ(1, nextPowTwoFunc(0u));                               \
  93   EXPECT_EQ(1, nextPowTwoFunc(1u));                               \
  94   EXPECT_EQ(2, nextPowTwoFunc(2u));                               \
  95   EXPECT_EQ(4, nextPowTwoFunc(3u));                               \
  96   EXPECT_EQ(4, nextPowTwoFunc(4u));                               \
  97   EXPECT_EQ(8, nextPowTwoFunc(5u));                               \
  98   EXPECT_EQ(8, nextPowTwoFunc(6u));                               \
  99   EXPECT_EQ(8, nextPowTwoFunc(7u));                               \
 100   EXPECT_EQ(8, nextPowTwoFunc(8u));                               \
 101   EXPECT_EQ(16, nextPowTwoFunc(9u));                              \
 102   EXPECT_EQ(16, nextPowTwoFunc(13u));                             \
 103   EXPECT_EQ(16, nextPowTwoFunc(16u));                             \
 104   EXPECT_EQ(512, nextPowTwoFunc(510u));                           \
 105   EXPECT_EQ(512, nextPowTwoFunc(511u));                           \
 106   EXPECT_EQ(512, nextPowTwoFunc(512u));                           \
 107   EXPECT_EQ(1024, nextPowTwoFunc(513u));                          \
 108   EXPECT_EQ(1024, nextPowTwoFunc(777u));                          \
 109   EXPECT_EQ(1ul << 31, nextPowTwoFunc((1ul << 31) - 1));          \
 110   EXPECT_EQ(1ull << 32, nextPowTwoFunc((1ull << 32) - 1));        \
 111   EXPECT_EQ(1ull << 63, nextPowTwoFunc((1ull << 62) + 1));        \
 112 }
 113
 114
 115 TEST(Bits, nextPowTwoClz) {
 116   testPowTwo(nextPowTwo);
 117 }
 118
 119 TEST(Bits, isPowTwo) {
 120   EXPECT_FALSE(isPowTwo(0u));
 121   EXPECT_TRUE(isPowTwo(1ul));
 122   EXPECT_TRUE(isPowTwo(2ull));
 123   EXPECT_FALSE(isPowTwo(3ul));
 124   EXPECT_TRUE(isPowTwo(4ul));
 125   EXPECT_FALSE(isPowTwo(5ul));
 126   EXPECT_TRUE(isPowTwo(8ul));
 127   EXPECT_FALSE(isPowTwo(15u));
 128   EXPECT_TRUE(isPowTwo(16u));
 129   EXPECT_FALSE(isPowTwo(17u));
 130   EXPECT_FALSE(isPowTwo(511ul));
 131   EXPECT_TRUE(isPowTwo(512ul));
 132   EXPECT_FALSE(isPowTwo(513ul));
 133   EXPECT_FALSE(isPowTwo((1ul<<31) - 1));
 134   EXPECT_TRUE(isPowTwo(1ul<<31));
 135   EXPECT_FALSE(isPowTwo((1ul<<31) + 1));
 136   EXPECT_FALSE(isPowTwo((1ull<<63) - 1));
 137   EXPECT_TRUE(isPowTwo(1ull<<63));
 138   EXPECT_FALSE(isPowTwo((1ull<<63) + 1));
 139 }
 140
 141 TEST(Bits, popcount) {
 142   EXPECT_EQ(0, popcount(0U));
 143   EXPECT_EQ(1, popcount(1U));
 144   EXPECT_EQ(32, popcount(uint32_t(-1)));
 145   EXPECT_EQ(64, popcount(uint64_t(-1)));
 146 }