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