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 <cstddef>
21#include <cstdint>
22#include <limits>
23#include <type_traits>
24
25#include "test_macros.h"
26
27struct A {};
28enum E1 : unsigned char { rEd };
29enum class E2 : unsigned char { red };
30
31template <class T>
32constexpr bool test()
33{
34 ASSERT_SAME_TYPE(decltype(std::countr_zero(T())), int);
35 ASSERT_NOEXCEPT(std::countr_zero(T()));
36 T max = std::numeric_limits<T>::max();
37
38 assert(std::countr_zero(T(0)) == std::numeric_limits<T>::digits);
39 assert(std::countr_zero(T(1)) == 0);
40 assert(std::countr_zero(T(2)) == 1);
41 assert(std::countr_zero(T(3)) == 0);
42 assert(std::countr_zero(T(4)) == 2);
43 assert(std::countr_zero(T(5)) == 0);
44 assert(std::countr_zero(T(6)) == 1);
45 assert(std::countr_zero(T(7)) == 0);
46 assert(std::countr_zero(T(8)) == 3);
47 assert(std::countr_zero(T(9)) == 0);
48 assert(std::countr_zero(T(126)) == 1);
49 assert(std::countr_zero(T(127)) == 0);
50 assert(std::countr_zero(T(128)) == 7);
51 assert(std::countr_zero(T(129)) == 0);
52 assert(std::countr_zero(T(130)) == 1);
53 assert(std::countr_zero(max) == 0);
54
55#ifndef TEST_HAS_NO_INT128
56 if constexpr (std::is_same_v<T, __uint128_t>) {
57 T val = T(128) << 32;
58 assert(std::countr_zero(val-1) == 0);
59 assert(std::countr_zero(val) == 39);
60 assert(std::countr_zero(val+1) == 0);
61 val <<= 60;
62 assert(std::countr_zero(val-1) == 0);
63 assert(std::countr_zero(val) == 99);
64 assert(std::countr_zero(val+1) == 0);
65 }
66#endif
67
68 return true;
69}
70
71int main(int, char**)
72{
73 {
74 auto lambda = [](auto x) -> decltype(std::countr_zero(x)) {};
75 using L = decltype(lambda);
76
77 static_assert(!std::is_invocable_v<L, signed char>);
78 static_assert(!std::is_invocable_v<L, short>);
79 static_assert(!std::is_invocable_v<L, int>);
80 static_assert(!std::is_invocable_v<L, long>);
81 static_assert(!std::is_invocable_v<L, long long>);
82#ifndef TEST_HAS_NO_INT128
83 static_assert(!std::is_invocable_v<L, __int128_t>);
84#endif
85
86 static_assert(!std::is_invocable_v<L, std::int8_t>);
87 static_assert(!std::is_invocable_v<L, std::int16_t>);
88 static_assert(!std::is_invocable_v<L, std::int32_t>);
89 static_assert(!std::is_invocable_v<L, std::int64_t>);
90 static_assert(!std::is_invocable_v<L, std::intmax_t>);
91 static_assert(!std::is_invocable_v<L, std::intptr_t>);
92 static_assert(!std::is_invocable_v<L, std::ptrdiff_t>);
93
94 static_assert(!std::is_invocable_v<L, bool>);
95 static_assert(!std::is_invocable_v<L, char>);
96 static_assert(!std::is_invocable_v<L, wchar_t>);
97#ifndef TEST_HAS_NO_CHAR8_T
98 static_assert(!std::is_invocable_v<L, char8_t>);
99#endif
100 static_assert(!std::is_invocable_v<L, char16_t>);
101 static_assert(!std::is_invocable_v<L, char32_t>);
102
103 static_assert(!std::is_invocable_v<L, A>);
104 static_assert(!std::is_invocable_v<L, A*>);
105 static_assert(!std::is_invocable_v<L, E1>);
106 static_assert(!std::is_invocable_v<L, E2>);
107 }
108
109 static_assert(test<unsigned char>());
110 static_assert(test<unsigned short>());
111 static_assert(test<unsigned int>());
112 static_assert(test<unsigned long>());
113 static_assert(test<unsigned long long>());
114#ifndef TEST_HAS_NO_INT128
115 static_assert(test<__uint128_t>());
116#endif
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 test<std::uint8_t>();
134 test<std::uint16_t>();
135 test<std::uint32_t>();
136 test<std::uint64_t>();
137 test<std::uintmax_t>();
138 test<std::uintptr_t>();
139 test<std::size_t>();
140
141 return 0;
142}
143

source code of libcxx/test/std/numerics/bit/bitops.count/countr_zero.pass.cpp