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1// -*- C++ -*-
2//===------------------------------ bit ----------------------------------===//
3//
4//                     The LLVM Compiler Infrastructure
5//
6// This file is dual licensed under the MIT and the University of Illinois Open
7// Source Licenses. See LICENSE.TXT for details.
8//
9//===---------------------------------------------------------------------===//
10
11#ifndef _LIBCPP_BIT
12#define _LIBCPP_BIT
13
14/*
15    bit synopsis
16
17namespace std {
18
19} // namespace std
20
21*/
22
23#include <__config>
24#include <version>
25
26#if defined(__IBMCPP__)
27#include "support/ibm/support.h"
28#endif
29#if defined(_LIBCPP_COMPILER_MSVC)
30#include <intrin.h>
31#endif
32
33#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
34#pragma GCC system_header
35#endif
36
37_LIBCPP_BEGIN_NAMESPACE_STD
38
39#ifndef _LIBCPP_COMPILER_MSVC
40
41inline _LIBCPP_INLINE_VISIBILITY
42int __ctz(unsigned __x)           { return __builtin_ctz(__x); }
43
44inline _LIBCPP_INLINE_VISIBILITY
45int __ctz(unsigned long __x)      { return __builtin_ctzl(__x); }
46
47inline _LIBCPP_INLINE_VISIBILITY
48int __ctz(unsigned long long __x) { return __builtin_ctzll(__x); }
49
50
51inline _LIBCPP_INLINE_VISIBILITY
52int __clz(unsigned __x)           { return __builtin_clz(__x); }
53
54inline _LIBCPP_INLINE_VISIBILITY
55int __clz(unsigned long __x)      { return __builtin_clzl(__x); }
56
57inline _LIBCPP_INLINE_VISIBILITY
58int __clz(unsigned long long __x) { return __builtin_clzll(__x); }
59
60
61inline _LIBCPP_INLINE_VISIBILITY
62int __popcount(unsigned __x)           { return __builtin_popcount(__x); }
63
64inline _LIBCPP_INLINE_VISIBILITY
65int __popcount(unsigned long __x)      { return __builtin_popcountl(__x); }
66
67inline _LIBCPP_INLINE_VISIBILITY
68int __popcount(unsigned long long __x) { return __builtin_popcountll(__x); }
69
70#else  // _LIBCPP_COMPILER_MSVC
71
72// Precondition:  __x != 0
73inline _LIBCPP_INLINE_VISIBILITY
74int __ctz(unsigned __x) {
75  static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
76  static_assert(sizeof(unsigned long) == 4, "");
77  unsigned long __where;
78  if (_BitScanForward(&__where, __x))
79    return static_cast<int>(__where);
80  return 32;
81}
82
83inline _LIBCPP_INLINE_VISIBILITY
84int __ctz(unsigned long __x) {
85    static_assert(sizeof(unsigned long) == sizeof(unsigned), "");
86    return __ctz(static_cast<unsigned>(__x));
87}
88
89inline _LIBCPP_INLINE_VISIBILITY
90int __ctz(unsigned long long __x) {
91    unsigned long __where;
92#if defined(_LIBCPP_HAS_BITSCAN64)
93    (defined(_M_AMD64) || defined(__x86_64__))
94  if (_BitScanForward64(&__where, __x))
95    return static_cast<int>(__where);
96#else
97  // Win32 doesn't have _BitScanForward64 so emulate it with two 32 bit calls.
98  if (_BitScanForward(&__where, static_cast<unsigned long>(__x)))
99    return static_cast<int>(__where);
100  if (_BitScanForward(&__where, static_cast<unsigned long>(__x >> 32)))
101    return static_cast<int>(__where + 32);
102#endif
103  return 64;
104}
105
106// Precondition:  __x != 0
107inline _LIBCPP_INLINE_VISIBILITY
108int __clz(unsigned __x) {
109  static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
110  static_assert(sizeof(unsigned long) == 4, "");
111  unsigned long __where;
112  if (_BitScanReverse(&__where, __x))
113    return static_cast<int>(31 - __where);
114  return 32; // Undefined Behavior.
115}
116
117inline _LIBCPP_INLINE_VISIBILITY
118int __clz(unsigned long __x) {
119    static_assert(sizeof(unsigned) == sizeof(unsigned long), "");
120    return __clz(static_cast<unsigned>(__x));
121}
122
123inline _LIBCPP_INLINE_VISIBILITY
124int __clz(unsigned long long __x) {
125  unsigned long __where;
126#if defined(_LIBCPP_HAS_BITSCAN64)
127  if (_BitScanReverse64(&__where, __x))
128    return static_cast<int>(63 - __where);
129#else
130  // Win32 doesn't have _BitScanReverse64 so emulate it with two 32 bit calls.
131  if (_BitScanReverse(&__where, static_cast<unsigned long>(__x >> 32)))
132    return static_cast<int>(63 - (__where + 32));
133  if (_BitScanReverse(&__where, static_cast<unsigned long>(__x)))
134    return static_cast<int>(63 - __where);
135#endif
136  return 64; // Undefined Behavior.
137}
138
139inline _LIBCPP_INLINE_VISIBILITY int __popcount(unsigned __x) {
140  static_assert(sizeof(unsigned) == 4, "");
141  return __popcnt(__x);
142}
143
144inline _LIBCPP_INLINE_VISIBILITY int __popcount(unsigned long __x) {
145  static_assert(sizeof(unsigned long) == 4, "");
146  return __popcnt(__x);
147}
148
149inline _LIBCPP_INLINE_VISIBILITY int __popcount(unsigned long long __x) {
150  static_assert(sizeof(unsigned long long) == 8, "");
151  return __popcnt64(__x);
152}
153
154#endif // _LIBCPP_COMPILER_MSVC
155
156_LIBCPP_END_NAMESPACE_STD
157
158#endif // _LIBCPP_BIT
159