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#ifndef _LIBCPP___BIT_COUNTR_H
10#define _LIBCPP___BIT_COUNTR_H
11
12#include <__bit/rotate.h>
13#include <__concepts/arithmetic.h>
14#include <__config>
15#include <limits>
16
17#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
18#  pragma GCC system_header
19#endif
20
21_LIBCPP_PUSH_MACROS
22#include <__undef_macros>
23
24_LIBCPP_BEGIN_NAMESPACE_STD
25
26inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
27int __libcpp_ctz(unsigned __x)           _NOEXCEPT { return __builtin_ctz(__x); }
28
29inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
30int __libcpp_ctz(unsigned long __x)      _NOEXCEPT { return __builtin_ctzl(__x); }
31
32inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
33int __libcpp_ctz(unsigned long long __x) _NOEXCEPT { return __builtin_ctzll(__x); }
34
35#if _LIBCPP_STD_VER >= 20
36
37template <__libcpp_unsigned_integer _Tp>
38_LIBCPP_HIDE_FROM_ABI constexpr int countr_zero(_Tp __t) noexcept {
39  if (__t == 0)
40    return numeric_limits<_Tp>::digits;
41
42  if (sizeof(_Tp) <= sizeof(unsigned int))
43    return std::__libcpp_ctz(static_cast<unsigned int>(__t));
44  else if (sizeof(_Tp) <= sizeof(unsigned long))
45    return std::__libcpp_ctz(static_cast<unsigned long>(__t));
46  else if (sizeof(_Tp) <= sizeof(unsigned long long))
47    return std::__libcpp_ctz(static_cast<unsigned long long>(__t));
48  else {
49    int __ret = 0;
50    const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits;
51    while (static_cast<unsigned long long>(__t) == 0uLL) {
52      __ret += __ulldigits;
53      __t >>= __ulldigits;
54    }
55    return __ret + std::__libcpp_ctz(static_cast<unsigned long long>(__t));
56  }
57}
58
59template <__libcpp_unsigned_integer _Tp>
60_LIBCPP_HIDE_FROM_ABI constexpr int countr_one(_Tp __t) noexcept {
61  return __t != numeric_limits<_Tp>::max() ? std::countr_zero(static_cast<_Tp>(~__t)) : numeric_limits<_Tp>::digits;
62}
63
64#endif // _LIBCPP_STD_VER >= 20
65
66_LIBCPP_END_NAMESPACE_STD
67
68_LIBCPP_POP_MACROS
69
70#endif // _LIBCPP___BIT_COUNTR_H
71