libcxx/test/std/numerics/bit/bit.pow.two/bit_floor.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 T bit_floor(T x) noexcept;
  13
  14 // Constraints: T is an unsigned integer type
  15 // Returns: If x == 0, 0; otherwise the maximal value y such that bit_floor(y) is true and y <= x.
  16
  17 #include <bit>
  18 #include <cassert>
  19 #include <cstddef>
  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::bit_floor(T())), T);
  34     LIBCPP_ASSERT_NOEXCEPT(std::bit_floor(T()));
  35     T max = std::numeric_limits<T>::max();
  36
  37     assert(std::bit_floor(T(0)) == T(0));
  38     assert(std::bit_floor(T(1)) == T(1));
  39     assert(std::bit_floor(T(2)) == T(2));
  40     assert(std::bit_floor(T(3)) == T(2));
  41     assert(std::bit_floor(T(4)) == T(4));
  42     assert(std::bit_floor(T(5)) == T(4));
  43     assert(std::bit_floor(T(6)) == T(4));
  44     assert(std::bit_floor(T(7)) == T(4));
  45     assert(std::bit_floor(T(8)) == T(8));
  46     assert(std::bit_floor(T(9)) == T(8));
  47     assert(std::bit_floor(T(125)) == T(64));
  48     assert(std::bit_floor(T(126)) == T(64));
  49     assert(std::bit_floor(T(127)) == T(64));
  50     assert(std::bit_floor(T(128)) == T(128));
  51     assert(std::bit_floor(T(129)) == T(128));
  52     assert(std::bit_floor(max) == T(max - (max >> 1)));
  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::bit_floor(val-1) == val/2);
  58         assert(std::bit_floor(val)   == val);
  59         assert(std::bit_floor(val+1) == val);
  60         val <<= 60;
  61         assert(std::bit_floor(val-1) == val/2);
  62         assert(std::bit_floor(val)   == val);
  63         assert(std::bit_floor(val+1) == val);
  64     }
  65 #endif
  66
  67     return true;
  68 }
  69
  70 int main(int, char**)
  71 {
  72     {
  73     auto lambda = [](auto x) -> decltype(std::bit_floor(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
 117     static_assert(test<std::uint8_t>());
 118     static_assert(test<std::uint16_t>());
 119     static_assert(test<std::uint32_t>());
 120     static_assert(test<std::uint64_t>());
 121     static_assert(test<std::uintmax_t>());
 122     static_assert(test<std::uintptr_t>());
 123     static_assert(test<std::size_t>());
 124
 125     test<unsigned char>();
 126     test<unsigned short>();
 127     test<unsigned int>();
 128     test<unsigned long>();
 129     test<unsigned long long>();
 130 #ifndef TEST_HAS_NO_INT128
 131     test<__uint128_t>();
 132 #endif
 133
 134     test<std::uint8_t>();
 135     test<std::uint16_t>();
 136     test<std::uint32_t>();
 137     test<std::uint64_t>();
 138     test<std::uintmax_t>();
 139     test<std::uintptr_t>();
 140     test<std::size_t>();
 141
 142     return 0;
 143 }