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

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 // UNSUPPORTED: c++03, c++11, c++14, c++17
  10
  11 // template <class T>
  12 //   constexpr int countr_one(T x) noexcept;
  13
  14 // Constraints: T is an unsigned integer type
  15 // Returns: The number of consecutive 1 bits, starting from the least significant bit.
  16 //   [ Note: Returns N if x == std::numeric_limits<T>::max(). ]
  17
  18 #include <bit>
  19 #include <cassert>
  20 #include <cstddef>
  21 #include <cstdint>
  22 #include <limits>
  23 #include <type_traits>
  24
  25 #include "test_macros.h"
  26
  27 struct A {};
  28 enum       E1 : unsigned char { rEd };
  29 enum class E2 : unsigned char { red };
  30
  31 template <class T>
  32 constexpr bool test()
  33 {
  34     ASSERT_SAME_TYPE(decltype(std::countr_one(T())), int);
  35     ASSERT_NOEXCEPT(std::countr_one(T()));
  36     T max = std::numeric_limits<T>::max();
  37
  38     assert(std::countr_one(T(0)) == 0);
  39     assert(std::countr_one(T(1)) == 1);
  40     assert(std::countr_one(T(2)) == 0);
  41     assert(std::countr_one(T(3)) == 2);
  42     assert(std::countr_one(T(4)) == 0);
  43     assert(std::countr_one(T(5)) == 1);
  44     assert(std::countr_one(T(6)) == 0);
  45     assert(std::countr_one(T(7)) == 3);
  46     assert(std::countr_one(T(8)) == 0);
  47     assert(std::countr_one(T(9)) == 1);
  48     assert(std::countr_one(T(126)) == 0);
  49     assert(std::countr_one(T(127)) == 7);
  50     assert(std::countr_one(T(128)) == 0);
  51     assert(std::countr_one(T(max - 1)) == 0);
  52     assert(std::countr_one(max) == std::numeric_limits<T>::digits);
  53
  54 #ifndef TEST_HAS_NO_INT128
  55     if constexpr (std::is_same_v<T, __uint128_t>) {
  56         T val = 128;
  57         assert(std::countr_one(val-1) ==  7);
  58         assert(std::countr_one(val)   ==  0);
  59         assert(std::countr_one(val+1) ==  1);
  60         val <<= 32;
  61         assert(std::countr_one(val-1) == 39);
  62         assert(std::countr_one(val)   ==  0);
  63         assert(std::countr_one(val+1) ==  1);
  64         val <<= 60;
  65         assert(std::countr_one(val-1) == 99);
  66         assert(std::countr_one(val)   ==  0);
  67         assert(std::countr_one(val+1) ==  1);
  68     }
  69 #endif
  70
  71     return true;
  72 }
  73
  74 int main(int, char**)
  75 {
  76     {
  77     auto lambda = [](auto x) -> decltype(std::countr_one(x)) {};
  78     using L = decltype(lambda);
  79
  80     static_assert(!std::is_invocable_v<L, signed char>);
  81     static_assert(!std::is_invocable_v<L, short>);
  82     static_assert(!std::is_invocable_v<L, int>);
  83     static_assert(!std::is_invocable_v<L, long>);
  84     static_assert(!std::is_invocable_v<L, long long>);
  85 #ifndef TEST_HAS_NO_INT128
  86     static_assert(!std::is_invocable_v<L, __int128_t>);
  87 #endif
  88
  89     static_assert(!std::is_invocable_v<L, std::int8_t>);
  90     static_assert(!std::is_invocable_v<L, std::int16_t>);
  91     static_assert(!std::is_invocable_v<L, std::int32_t>);
  92     static_assert(!std::is_invocable_v<L, std::int64_t>);
  93     static_assert(!std::is_invocable_v<L, std::intmax_t>);
  94     static_assert(!std::is_invocable_v<L, std::intptr_t>);
  95     static_assert(!std::is_invocable_v<L, std::ptrdiff_t>);
  96
  97     static_assert(!std::is_invocable_v<L, bool>);
  98     static_assert(!std::is_invocable_v<L, char>);
  99     static_assert(!std::is_invocable_v<L, wchar_t>);
 100 #ifndef TEST_HAS_NO_CHAR8_T
 101     static_assert(!std::is_invocable_v<L, char8_t>);
 102 #endif
 103     static_assert(!std::is_invocable_v<L, char16_t>);
 104     static_assert(!std::is_invocable_v<L, char32_t>);
 105
 106     static_assert(!std::is_invocable_v<L, A>);
 107     static_assert(!std::is_invocable_v<L, A*>);
 108     static_assert(!std::is_invocable_v<L, E1>);
 109     static_assert(!std::is_invocable_v<L, E2>);
 110     }
 111
 112     static_assert(test<unsigned char>());
 113     static_assert(test<unsigned short>());
 114     static_assert(test<unsigned int>());
 115     static_assert(test<unsigned long>());
 116     static_assert(test<unsigned long long>());
 117 #ifndef TEST_HAS_NO_INT128
 118     static_assert(test<__uint128_t>());
 119 #endif
 120     static_assert(test<std::uint8_t>());
 121     static_assert(test<std::uint16_t>());
 122     static_assert(test<std::uint32_t>());
 123     static_assert(test<std::uint64_t>());
 124     static_assert(test<std::uintmax_t>());
 125     static_assert(test<std::uintptr_t>());
 126     static_assert(test<std::size_t>());
 127
 128     test<unsigned char>();
 129     test<unsigned short>();
 130     test<unsigned int>();
 131     test<unsigned long>();
 132     test<unsigned long long>();
 133 #ifndef TEST_HAS_NO_INT128
 134     test<__uint128_t>();
 135 #endif
 136     test<std::uint8_t>();
 137     test<std::uint16_t>();
 138     test<std::uint32_t>();
 139     test<std::uint64_t>();
 140     test<std::uintmax_t>();
 141     test<std::uintptr_t>();
 142     test<std::size_t>();
 143
 144     return 0;
 145 }