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gerrit.openfyde.cn / chromium.googlesource.com / external / github.com / llvm / llvm-project / libcxx / 908210951c2b9437cd7f0c61c1afad79c756c908 / . / include / __bits
blob: 0d321da9228554df86ee0b24b88fc3cb99429844 [file] [log] [blame]
Thorsten Schütt90821092021-01-18 13:21:00 +0100[diff] [blame^]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___BITS
11#define _LIBCPP___BITS
12
13#include <__config>
14
15#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
16#pragma GCC system_header
17#endif
18
19_LIBCPP_PUSH_MACROS
20#include <__undef_macros>
21
22
23_LIBCPP_BEGIN_NAMESPACE_STD
24
25#ifndef _LIBCPP_COMPILER_MSVC
26
27inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
28int __libcpp_ctz(unsigned __x) _NOEXCEPT { return __builtin_ctz(__x); }
29
30inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
31int __libcpp_ctz(unsigned long __x) _NOEXCEPT { return __builtin_ctzl(__x); }
32
33inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
34int __libcpp_ctz(unsigned long long __x) _NOEXCEPT { return __builtin_ctzll(__x); }
35
36
37inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
38int __libcpp_clz(unsigned __x) _NOEXCEPT { return __builtin_clz(__x); }
39
40inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
41int __libcpp_clz(unsigned long __x) _NOEXCEPT { return __builtin_clzl(__x); }
42
43inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
44int __libcpp_clz(unsigned long long __x) _NOEXCEPT { return __builtin_clzll(__x); }
45
46
47inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
48int __libcpp_popcount(unsigned __x) _NOEXCEPT { return __builtin_popcount(__x); }
49
50inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
51int __libcpp_popcount(unsigned long __x) _NOEXCEPT { return __builtin_popcountl(__x); }
52
53inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
54int __libcpp_popcount(unsigned long long __x) _NOEXCEPT { return __builtin_popcountll(__x); }
55
56#else // _LIBCPP_COMPILER_MSVC
57
58// Precondition: __x != 0
59inline _LIBCPP_INLINE_VISIBILITY
60int __libcpp_ctz(unsigned __x) {
61 static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
62 static_assert(sizeof(unsigned long) == 4, "");
63 unsigned long __where;
64 if (_BitScanForward(&__where, __x))
65 return static_cast<int>(__where);
66 return 32;
67}
68
69inline _LIBCPP_INLINE_VISIBILITY
70int __libcpp_ctz(unsigned long __x) {
71 static_assert(sizeof(unsigned long) == sizeof(unsigned), "");
72 return __ctz(static_cast<unsigned>(__x));
73}
74
75inline _LIBCPP_INLINE_VISIBILITY
76int __libcpp_ctz(unsigned long long __x) {
77 unsigned long __where;
78#if defined(_LIBCPP_HAS_BITSCAN64)
79 (defined(_M_AMD64) || defined(__x86_64__))
80 if (_BitScanForward64(&__where, __x))
81 return static_cast<int>(__where);
82#else
83 // Win32 doesn't have _BitScanForward64 so emulate it with two 32 bit calls.
84 if (_BitScanForward(&__where, static_cast<unsigned long>(__x)))
85 return static_cast<int>(__where);
86 if (_BitScanForward(&__where, static_cast<unsigned long>(__x >> 32)))
87 return static_cast<int>(__where + 32);
88#endif
89 return 64;
90}
91
92// Precondition: __x != 0
93inline _LIBCPP_INLINE_VISIBILITY
94int __libcpp_clz(unsigned __x) {
95 static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
96 static_assert(sizeof(unsigned long) == 4, "");
97 unsigned long __where;
98 if (_BitScanReverse(&__where, __x))
99 return static_cast<int>(31 - __where);
100 return 32; // Undefined Behavior.
101}
102
103inline _LIBCPP_INLINE_VISIBILITY
104int __libcpp_clz(unsigned long __x) {
105 static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
106 return __libcpp_clz(static_cast<unsigned>(__x));
107}
108
109inline _LIBCPP_INLINE_VISIBILITY
110int __libcpp_clz(unsigned long long __x) {
111 unsigned long __where;
112#if defined(_LIBCPP_HAS_BITSCAN64)
113 if (_BitScanReverse64(&__where, __x))
114 return static_cast<int>(63 - __where);
115#else
116 // Win32 doesn't have _BitScanReverse64 so emulate it with two 32 bit calls.
117 if (_BitScanReverse(&__where, static_cast<unsigned long>(__x >> 32)))
118 return static_cast<int>(63 - (__where + 32));
119 if (_BitScanReverse(&__where, static_cast<unsigned long>(__x)))
120 return static_cast<int>(63 - __where);
121#endif
122 return 64; // Undefined Behavior.
123}
124
125inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned __x) {
126 static_assert(sizeof(unsigned) == 4, "");
127 return __popcnt(__x);
128}
129
130inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned long __x) {
131 static_assert(sizeof(unsigned long) == 4, "");
132 return __popcnt(__x);
133}
134
135inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned long long __x) {
136 static_assert(sizeof(unsigned long long) == 8, "");
137 return __popcnt64(__x);
138}
139
140#endif // _LIBCPP_COMPILER_MSVC
141
142_LIBCPP_END_NAMESPACE_STD
143
144_LIBCPP_POP_MACROS
145
146#endif // _LIBCPP__BITS