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 <folly/portability/GTest.h>
  22
  23 using namespace folly;
  24
  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");
  30 #endif
  31
  32 #ifndef __clang__
  33 static_assert(isPowTwo(2u), "isPowTwo");
  34 #endif
  35
  36 namespace {
  37
  38 template <class INT>
  39 void testFFS() {
  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));
  47   }
  48 }
  49
  50 template <class INT>
  51 void testFLS() {
  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));
  58
  59     INT v2 = (static_cast<UINT>(1) << i) - 1;
  60     EXPECT_EQ(i, findLastSet(v2));
  61   }
  62 }
  63
  64 }  // namespace
  65
  66 TEST(Bits, FindFirstSet) {
  67   testFFS<char>();
  68   testFFS<signed char>();
  69   testFFS<unsigned char>();
  70   testFFS<short>();
  71   testFFS<unsigned short>();
  72   testFFS<int>();
  73   testFFS<unsigned int>();
  74   testFFS<long>();
  75   testFFS<unsigned long>();
  76   testFFS<long long>();
  77   testFFS<unsigned long long>();
  78 }
  79
  80 TEST(Bits, FindLastSet) {
  81   testFLS<char>();
  82   testFLS<signed char>();
  83   testFLS<unsigned char>();
  84   testFLS<short>();
  85   testFLS<unsigned short>();
  86   testFLS<int>();
  87   testFLS<unsigned int>();
  88   testFLS<long>();
  89   testFLS<unsigned long>();
  90   testFLS<long long>();
  91   testFLS<unsigned long long>();
  92 }
  93
  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));
 115 }
 116
 117 TEST(Bits, isPowTwo) {
 118   EXPECT_FALSE(isPowTwo(0u));
 119   EXPECT_TRUE(isPowTwo(1ul));
 120   EXPECT_TRUE(isPowTwo(2ull));
 121   EXPECT_FALSE(isPowTwo(3ul));
 122   EXPECT_TRUE(isPowTwo(4ul));
 123   EXPECT_FALSE(isPowTwo(5ul));
 124   EXPECT_TRUE(isPowTwo(8ul));
 125   EXPECT_FALSE(isPowTwo(15u));
 126   EXPECT_TRUE(isPowTwo(16u));
 127   EXPECT_FALSE(isPowTwo(17u));
 128   EXPECT_FALSE(isPowTwo(511ul));
 129   EXPECT_TRUE(isPowTwo(512ul));
 130   EXPECT_FALSE(isPowTwo(513ul));
 131   EXPECT_FALSE(isPowTwo((1ul<<31) - 1));
 132   EXPECT_TRUE(isPowTwo(1ul<<31));
 133   EXPECT_FALSE(isPowTwo((1ul<<31) + 1));
 134   EXPECT_FALSE(isPowTwo((1ull<<63) - 1));
 135   EXPECT_TRUE(isPowTwo(1ull<<63));
 136   EXPECT_FALSE(isPowTwo((1ull<<63) + 1));
 137 }
 138
 139 TEST(Bits, popcount) {
 140   EXPECT_EQ(0, popcount(0U));
 141   EXPECT_EQ(1, popcount(1U));
 142   EXPECT_EQ(32, popcount(uint32_t(-1)));
 143   EXPECT_EQ(64, popcount(uint64_t(-1)));
 144 }