libcxx/test/std/numerics/bit/bitops.count/countr_one.pass.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is dual licensed under the MIT and the University of Illinois Open
   6 // Source Licenses. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 // UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
  10
  11 // template <class T>
  12 //   constexpr int countr_one(T x) noexcept;
  13
  14 // Returns: The number of consecutive 1 bits, starting from the least significant bit.
  15 //   [ Note: Returns N if x == std::numeric_limits<T>::max(). ]
  16 //
  17 // Remarks: This function shall not participate in overload resolution unless
  18 //      T is an unsigned integer type
  19
  20 #include <bit>
  21 #include <cstdint>
  22 #include <type_traits>
  23 #include <cassert>
  24
  25 #include "test_macros.h"
  26
  27 class A{};
  28 enum       E1 : unsigned char { rEd };
  29 enum class E2 : unsigned char { red };
  30
  31 template <typename T>
  32 constexpr bool constexpr_test()
  33 {
  34         const int dig = std::numeric_limits<T>::digits;
  35         return std::countr_one(T(0)) == 0
  36            &&  std::countr_one(T(1)) == 1
  37            &&  std::countr_one(T(2)) == 0
  38            &&  std::countr_one(T(3)) == 2
  39            &&  std::countr_one(T(4)) == 0
  40            &&  std::countr_one(T(5)) == 1
  41            &&  std::countr_one(T(6)) == 0
  42            &&  std::countr_one(T(7)) == 3
  43            &&  std::countr_one(T(8)) == 0
  44            &&  std::countr_one(T(9)) == 1
  45            &&  std::countr_one(std::numeric_limits<T>::max()) == dig
  46           ;
  47 }
  48
  49
  50 template <typename T>
  51 void runtime_test()
  52 {
  53         ASSERT_SAME_TYPE(int, decltype(std::countr_one(T(0))));
  54         ASSERT_NOEXCEPT(               std::countr_one(T(0)));
  55
  56         assert( std::countr_one(T(121)) == 1);
  57         assert( std::countr_one(T(122)) == 0);
  58         assert( std::countr_one(T(123)) == 2);
  59         assert( std::countr_one(T(124)) == 0);
  60         assert( std::countr_one(T(125)) == 1);
  61         assert( std::countr_one(T(126)) == 0);
  62         assert( std::countr_one(T(127)) == 7);
  63         assert( std::countr_one(T(128)) == 0);
  64         assert( std::countr_one(T(129)) == 1);
  65         assert( std::countr_one(T(130)) == 0);
  66 }
  67
  68 int main()
  69 {
  70
  71     {
  72     auto lambda = [](auto x) -> decltype(std::countr_one(x)) {};
  73     using L = decltype(lambda);
  74
  75     static_assert( std::is_invocable_v<L, unsigned char>, "");
  76     static_assert( std::is_invocable_v<L, unsigned int>, "");
  77     static_assert( std::is_invocable_v<L, unsigned long>, "");
  78     static_assert( std::is_invocable_v<L, unsigned long long>, "");
  79
  80     static_assert( std::is_invocable_v<L, uint8_t>, "");
  81     static_assert( std::is_invocable_v<L, uint16_t>, "");
  82     static_assert( std::is_invocable_v<L, uint32_t>, "");
  83     static_assert( std::is_invocable_v<L, uint64_t>, "");
  84     static_assert( std::is_invocable_v<L, size_t>, "");
  85
  86     static_assert( std::is_invocable_v<L, uintmax_t>, "");
  87     static_assert( std::is_invocable_v<L, uintptr_t>, "");
  88
  89
  90     static_assert(!std::is_invocable_v<L, int>, "");
  91     static_assert(!std::is_invocable_v<L, signed int>, "");
  92     static_assert(!std::is_invocable_v<L, long>, "");
  93     static_assert(!std::is_invocable_v<L, long long>, "");
  94
  95     static_assert(!std::is_invocable_v<L, int8_t>, "");
  96     static_assert(!std::is_invocable_v<L, int16_t>, "");
  97     static_assert(!std::is_invocable_v<L, int32_t>, "");
  98     static_assert(!std::is_invocable_v<L, int64_t>, "");
  99     static_assert(!std::is_invocable_v<L, ptrdiff_t>, "");
 100
 101     static_assert(!std::is_invocable_v<L, bool>, "");
 102     static_assert(!std::is_invocable_v<L, signed char>, "");
 103     static_assert(!std::is_invocable_v<L, char16_t>, "");
 104     static_assert(!std::is_invocable_v<L, char32_t>, "");
 105
 106 #ifndef _LIBCPP_HAS_NO_INT128
 107     static_assert( std::is_invocable_v<L, __uint128_t>, "");
 108     static_assert(!std::is_invocable_v<L, __int128_t>, "");
 109 #endif
 110
 111     static_assert(!std::is_invocable_v<L, A>, "");
 112     static_assert(!std::is_invocable_v<L, E1>, "");
 113     static_assert(!std::is_invocable_v<L, E2>, "");
 114     }
 115
 116         static_assert(constexpr_test<unsigned char>(),      "");
 117         static_assert(constexpr_test<unsigned short>(),     "");
 118         static_assert(constexpr_test<unsigned>(),           "");
 119         static_assert(constexpr_test<unsigned long>(),      "");
 120         static_assert(constexpr_test<unsigned long long>(), "");
 121
 122         static_assert(constexpr_test<uint8_t>(),   "");
 123         static_assert(constexpr_test<uint16_t>(),  "");
 124         static_assert(constexpr_test<uint32_t>(),  "");
 125         static_assert(constexpr_test<uint64_t>(),  "");
 126         static_assert(constexpr_test<size_t>(),    "");
 127         static_assert(constexpr_test<uintmax_t>(), "");
 128         static_assert(constexpr_test<uintptr_t>(), "");
 129
 130 #ifndef _LIBCPP_HAS_NO_INT128
 131         static_assert(constexpr_test<__uint128_t>(),        "");
 132 #endif
 133
 134
 135         runtime_test<unsigned char>();
 136         runtime_test<unsigned>();
 137         runtime_test<unsigned short>();
 138         runtime_test<unsigned long>();
 139         runtime_test<unsigned long long>();
 140
 141         runtime_test<uint8_t>();
 142         runtime_test<uint16_t>();
 143         runtime_test<uint32_t>();
 144         runtime_test<uint64_t>();
 145         runtime_test<size_t>();
 146         runtime_test<uintmax_t>();
 147         runtime_test<uintptr_t>();
 148
 149 #ifndef _LIBCPP_HAS_NO_INT128
 150         runtime_test<__uint128_t>();
 151
 152         {
 153         __uint128_t val = 128;
 154
 155         val <<= 32;
 156         assert( std::countr_one(val-1) == 39);
 157         assert( std::countr_one(val)   ==  0);
 158         assert( std::countr_one(val+1) ==  1);
 159         val <<= 2;
 160         assert( std::countr_one(val-1) == 41);
 161         assert( std::countr_one(val)   ==  0);
 162         assert( std::countr_one(val+1) ==  1);
 163         val <<= 3;
 164         assert( std::countr_one(val-1) == 44);
 165         assert( std::countr_one(val)   ==  0);
 166         assert( std::countr_one(val+1) ==  1);
 167         }
 168 #endif
 169
 170 }