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 countl_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::countl_zero(T())), int);
35 ASSERT_NOEXCEPT(std::countl_zero(T()));
36 T max = std::numeric_limits<T>::max();
37 int dig = std::numeric_limits<T>::digits;
38
39 assert(std::countl_zero(T(0)) == dig);
40 assert(std::countl_zero(T(1)) == dig - 1);
41 assert(std::countl_zero(T(2)) == dig - 2);
42 assert(std::countl_zero(T(3)) == dig - 2);
43 assert(std::countl_zero(T(4)) == dig - 3);
44 assert(std::countl_zero(T(5)) == dig - 3);
45 assert(std::countl_zero(T(6)) == dig - 3);
46 assert(std::countl_zero(T(7)) == dig - 3);
47 assert(std::countl_zero(T(8)) == dig - 4);
48 assert(std::countl_zero(T(9)) == dig - 4);
49 assert(std::countl_zero(T(127)) == dig - 7);
50 assert(std::countl_zero(T(128)) == dig - 8);
51 assert(std::countl_zero(max) == 0);
52
53#ifndef TEST_HAS_NO_INT128
54 if constexpr (std::is_same_v<T, __uint128_t>) {
55 T val = T(128) << 32;
56 assert(std::countl_zero(val-1) == 89);
57 assert(std::countl_zero(val) == 88);
58 assert(std::countl_zero(val+1) == 88);
59 val <<= 60;
60 assert(std::countl_zero(val-1) == 29);
61 assert(std::countl_zero(val) == 28);
62 assert(std::countl_zero(val+1) == 28);
63 }
64#endif
65
66 return true;
67}
68
69int main(int, char**)
70{
71 {
72 auto lambda = [](auto x) -> decltype(std::countl_zero(x)) {};
73 using L = decltype(lambda);
74
75 static_assert(!std::is_invocable_v<L, signed char>);
76 static_assert(!std::is_invocable_v<L, short>);
77 static_assert(!std::is_invocable_v<L, int>);
78 static_assert(!std::is_invocable_v<L, long>);
79 static_assert(!std::is_invocable_v<L, long long>);
80#ifndef TEST_HAS_NO_INT128
81 static_assert(!std::is_invocable_v<L, __int128_t>);
82#endif
83
84 static_assert(!std::is_invocable_v<L, std::int8_t>);
85 static_assert(!std::is_invocable_v<L, std::int16_t>);
86 static_assert(!std::is_invocable_v<L, std::int32_t>);
87 static_assert(!std::is_invocable_v<L, std::int64_t>);
88 static_assert(!std::is_invocable_v<L, std::intmax_t>);
89 static_assert(!std::is_invocable_v<L, std::intptr_t>);
90 static_assert(!std::is_invocable_v<L, std::ptrdiff_t>);
91
92 static_assert(!std::is_invocable_v<L, bool>);
93 static_assert(!std::is_invocable_v<L, char>);
94 static_assert(!std::is_invocable_v<L, wchar_t>);
95#ifndef TEST_HAS_NO_CHAR8_T
96 static_assert(!std::is_invocable_v<L, char8_t>);
97#endif
98 static_assert(!std::is_invocable_v<L, char16_t>);
99 static_assert(!std::is_invocable_v<L, char32_t>);
100
101 static_assert(!std::is_invocable_v<L, A>);
102 static_assert(!std::is_invocable_v<L, A*>);
103 static_assert(!std::is_invocable_v<L, E1>);
104 static_assert(!std::is_invocable_v<L, E2>);
105 }
106
107 static_assert(test<unsigned char>());
108 static_assert(test<unsigned short>());
109 static_assert(test<unsigned int>());
110 static_assert(test<unsigned long>());
111 static_assert(test<unsigned long long>());
112#ifndef TEST_HAS_NO_INT128
113 static_assert(test<__uint128_t>());
114#endif
115 static_assert(test<std::uint8_t>());
116 static_assert(test<std::uint16_t>());
117 static_assert(test<std::uint32_t>());
118 static_assert(test<std::uint64_t>());
119 static_assert(test<std::uintmax_t>());
120 static_assert(test<std::uintptr_t>());
121 static_assert(test<std::size_t>());
122
123 test<unsigned char>();
124 test<unsigned short>();
125 test<unsigned int>();
126 test<unsigned long>();
127 test<unsigned long long>();
128#ifndef TEST_HAS_NO_INT128
129 test<__uint128_t>();
130#endif
131 test<std::uint8_t>();
132 test<std::uint16_t>();
133 test<std::uint32_t>();
134 test<std::uint64_t>();
135 test<std::uintmax_t>();
136 test<std::uintptr_t>();
137 test<std::size_t>();
138
139 return 0;
140}
141

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