1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===---------------------------------------------------------------------===//
9
10#ifndef _LIBCPP_BIT
11#define _LIBCPP_BIT
12
13/*
14    bit synopsis
15
16namespace std {
17  // [bit.cast], bit_cast
18  template<class To, class From>
19    constexpr To bit_cast(const From& from) noexcept; // C++20
20
21  // [bit.byteswap], byteswap
22  template<class T>
23    constexpr T byteswap(T value) noexcept;      // C++23
24
25  // [bit.pow.two], integral powers of 2
26  template <class T>
27    constexpr bool has_single_bit(T x) noexcept; // C++20
28  template <class T>
29    constexpr T bit_ceil(T x);                   // C++20
30  template <class T>
31    constexpr T bit_floor(T x) noexcept;         // C++20
32  template <class T>
33    constexpr int bit_width(T x) noexcept;       // C++20
34
35  // [bit.rotate], rotating
36  template<class T>
37    constexpr T rotl(T x, unsigned int s) noexcept; // C++20
38  template<class T>
39    constexpr T rotr(T x, unsigned int s) noexcept; // C++20
40
41  // [bit.count], counting
42  template<class T>
43    constexpr int countl_zero(T x) noexcept;  // C++20
44  template<class T>
45    constexpr int countl_one(T x) noexcept;   // C++20
46  template<class T>
47    constexpr int countr_zero(T x) noexcept;  // C++20
48  template<class T>
49    constexpr int countr_one(T x) noexcept;   // C++20
50  template<class T>
51    constexpr int popcount(T x) noexcept;     // C++20
52
53  // [bit.endian], endian
54  enum class endian {
55    little = see below,        // C++20
56    big = see below,           // C++20
57    native = see below         // C++20
58  };
59
60} // namespace std
61
62*/
63
64#include <__assert> // all public C++ headers provide the assertion handler
65#include <__bit/bit_cast.h>
66#include <__bit/byteswap.h>
67#include <__bits> // __libcpp_clz
68#include <__concepts/arithmetic.h>
69#include <__config>
70#include <limits>
71#include <type_traits>
72#include <version>
73
74#ifndef _LIBCPP_REMOVE_TRANSITIVE_INCLUDES
75#  include <iosfwd>
76#endif
77
78#if defined(_LIBCPP_COMPILER_MSVC)
79#  include <intrin.h>
80#endif
81
82#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
83#  pragma GCC system_header
84#endif
85
86_LIBCPP_PUSH_MACROS
87#include <__undef_macros>
88
89_LIBCPP_BEGIN_NAMESPACE_STD
90
91template<class _Tp>
92_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
93_Tp __rotr(_Tp __t, unsigned int __cnt) _NOEXCEPT
94{
95    static_assert(__libcpp_is_unsigned_integer<_Tp>::value, "__rotr requires an unsigned integer type");
96    const unsigned int __dig = numeric_limits<_Tp>::digits;
97    if ((__cnt % __dig) == 0)
98        return __t;
99    return (__t >> (__cnt % __dig)) | (__t << (__dig - (__cnt % __dig)));
100}
101
102template<class _Tp>
103_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
104int __countl_zero(_Tp __t) _NOEXCEPT
105{
106    static_assert(__libcpp_is_unsigned_integer<_Tp>::value, "__countl_zero requires an unsigned integer type");
107    if (__t == 0)
108        return numeric_limits<_Tp>::digits;
109
110    if      (sizeof(_Tp) <= sizeof(unsigned int))
111        return std::__libcpp_clz(static_cast<unsigned int>(__t))
112              - (numeric_limits<unsigned int>::digits - numeric_limits<_Tp>::digits);
113    else if (sizeof(_Tp) <= sizeof(unsigned long))
114        return std::__libcpp_clz(static_cast<unsigned long>(__t))
115              - (numeric_limits<unsigned long>::digits - numeric_limits<_Tp>::digits);
116    else if (sizeof(_Tp) <= sizeof(unsigned long long))
117        return std::__libcpp_clz(static_cast<unsigned long long>(__t))
118              - (numeric_limits<unsigned long long>::digits - numeric_limits<_Tp>::digits);
119    else
120    {
121        int __ret = 0;
122        int __iter = 0;
123        const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits;
124        while (true) {
125            __t = std::__rotr(__t, __ulldigits);
126            if ((__iter = std::__countl_zero(static_cast<unsigned long long>(__t))) != __ulldigits)
127                break;
128            __ret += __iter;
129            }
130        return __ret + __iter;
131    }
132}
133
134#if _LIBCPP_STD_VER > 17
135
136template <__libcpp_unsigned_integer _Tp>
137_LIBCPP_HIDE_FROM_ABI constexpr _Tp rotl(_Tp __t, unsigned int __cnt) noexcept {
138  const unsigned int __dig = numeric_limits<_Tp>::digits;
139  if ((__cnt % __dig) == 0)
140    return __t;
141  return (__t << (__cnt % __dig)) | (__t >> (__dig - (__cnt % __dig)));
142}
143
144template <__libcpp_unsigned_integer _Tp>
145_LIBCPP_HIDE_FROM_ABI constexpr _Tp rotr(_Tp __t, unsigned int __cnt) noexcept {
146  return std::__rotr(__t, __cnt);
147}
148
149template <__libcpp_unsigned_integer _Tp>
150_LIBCPP_HIDE_FROM_ABI constexpr int countl_zero(_Tp __t) noexcept {
151  return std::__countl_zero(__t);
152}
153
154template <__libcpp_unsigned_integer _Tp>
155_LIBCPP_HIDE_FROM_ABI constexpr int countl_one(_Tp __t) noexcept {
156  return __t != numeric_limits<_Tp>::max() ? std::countl_zero(static_cast<_Tp>(~__t)) : numeric_limits<_Tp>::digits;
157}
158
159template <__libcpp_unsigned_integer _Tp>
160_LIBCPP_HIDE_FROM_ABI constexpr int countr_zero(_Tp __t) noexcept {
161  if (__t == 0)
162    return numeric_limits<_Tp>::digits;
163
164  if (sizeof(_Tp) <= sizeof(unsigned int))
165    return std::__libcpp_ctz(static_cast<unsigned int>(__t));
166  else if (sizeof(_Tp) <= sizeof(unsigned long))
167    return std::__libcpp_ctz(static_cast<unsigned long>(__t));
168  else if (sizeof(_Tp) <= sizeof(unsigned long long))
169    return std::__libcpp_ctz(static_cast<unsigned long long>(__t));
170  else {
171    int __ret = 0;
172    const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits;
173    while (static_cast<unsigned long long>(__t) == 0uLL) {
174      __ret += __ulldigits;
175      __t >>= __ulldigits;
176    }
177    return __ret + std::__libcpp_ctz(static_cast<unsigned long long>(__t));
178  }
179}
180
181template <__libcpp_unsigned_integer _Tp>
182_LIBCPP_HIDE_FROM_ABI constexpr int countr_one(_Tp __t) noexcept {
183  return __t != numeric_limits<_Tp>::max() ? std::countr_zero(static_cast<_Tp>(~__t)) : numeric_limits<_Tp>::digits;
184}
185
186template <__libcpp_unsigned_integer _Tp>
187_LIBCPP_HIDE_FROM_ABI constexpr int popcount(_Tp __t) noexcept {
188  if (sizeof(_Tp) <= sizeof(unsigned int))
189    return std::__libcpp_popcount(static_cast<unsigned int>(__t));
190  else if (sizeof(_Tp) <= sizeof(unsigned long))
191    return std::__libcpp_popcount(static_cast<unsigned long>(__t));
192  else if (sizeof(_Tp) <= sizeof(unsigned long long))
193    return std::__libcpp_popcount(static_cast<unsigned long long>(__t));
194  else {
195    int __ret = 0;
196    while (__t != 0) {
197      __ret += std::__libcpp_popcount(static_cast<unsigned long long>(__t));
198      __t >>= numeric_limits<unsigned long long>::digits;
199    }
200    return __ret;
201  }
202}
203
204template <__libcpp_unsigned_integer _Tp>
205_LIBCPP_HIDE_FROM_ABI constexpr bool has_single_bit(_Tp __t) noexcept {
206  return __t != 0 && (((__t & (__t - 1)) == 0));
207}
208
209// integral log base 2
210template <__libcpp_unsigned_integer _Tp>
211_LIBCPP_HIDE_FROM_ABI constexpr _Tp __bit_log2(_Tp __t) noexcept {
212  return numeric_limits<_Tp>::digits - 1 - std::countl_zero(__t);
213}
214
215template <__libcpp_unsigned_integer _Tp>
216_LIBCPP_HIDE_FROM_ABI constexpr _Tp bit_floor(_Tp __t) noexcept {
217  return __t == 0 ? 0 : _Tp{1} << std::__bit_log2(__t);
218}
219
220template <__libcpp_unsigned_integer _Tp>
221_LIBCPP_HIDE_FROM_ABI constexpr _Tp bit_ceil(_Tp __t) noexcept {
222  if (__t < 2)
223    return 1;
224  const unsigned __n = numeric_limits<_Tp>::digits - std::countl_zero((_Tp)(__t - 1u));
225  _LIBCPP_ASSERT(__n != numeric_limits<_Tp>::digits, "Bad input to bit_ceil");
226
227  if constexpr (sizeof(_Tp) >= sizeof(unsigned))
228    return _Tp{1} << __n;
229  else {
230    const unsigned __extra = numeric_limits<unsigned>::digits - numeric_limits<_Tp>::digits;
231    const unsigned __retVal = 1u << (__n + __extra);
232    return (_Tp)(__retVal >> __extra);
233  }
234}
235
236template <__libcpp_unsigned_integer _Tp>
237_LIBCPP_HIDE_FROM_ABI constexpr int bit_width(_Tp __t) noexcept {
238  return __t == 0 ? 0 : std::__bit_log2(__t) + 1;
239}
240
241enum class endian {
242  little = 0xDEAD,
243  big = 0xFACE,
244#  if defined(_LIBCPP_LITTLE_ENDIAN)
245  native = little
246#  elif defined(_LIBCPP_BIG_ENDIAN)
247  native = big
248#  else
249  native = 0xCAFE
250#  endif
251};
252
253#endif // _LIBCPP_STD_VER > 17
254
255_LIBCPP_END_NAMESPACE_STD
256
257_LIBCPP_POP_MACROS
258
259#endif // _LIBCPP_BIT
260