1 // -*- C++ -*-
2 //===----------------------- support/win32/support.h ----------------------===//
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_SUPPORT_WIN32_SUPPORT_H
12 #define _LIBCPP_SUPPORT_WIN32_SUPPORT_H
13
14 // Functions and constants used in libc++ that
15 // are missing from the Windows C library.
16
17 #include <wchar.h> // mbstate_t
18 #include <cstdarg> // va_ macros
19 // "builtins" not implemented here for Clang or GCC as they provide
20 // implementations. Assuming required for elsewhere else, certainly MSVC.
21 #if defined(_LIBCPP_MSVC)
22 #include <intrin.h>
23 #endif
24 #if defined(_LIBCPP_MSVCRT)
25 #include <xlocinfo.h>
26 #endif
27 #define swprintf _snwprintf
28 #define vswprintf _vsnwprintf
29
30 #ifndef NOMINMAX
31 #define NOMINMAX
32 #endif
33
34 extern "C" {
35
36 int vasprintf(char **sptr, const char *__restrict fmt, va_list ap);
37 int asprintf(char **sptr, const char *__restrict fmt, ...);
38 size_t mbsnrtowcs(wchar_t *__restrict dst, const char **__restrict src,
39 size_t nmc, size_t len, mbstate_t *__restrict ps);
40 size_t wcsnrtombs(char *__restrict dst, const wchar_t **__restrict src,
41 size_t nwc, size_t len, mbstate_t *__restrict ps);
42 }
43
44 #if defined(_LIBCPP_MSVCRT)
45 #define snprintf _snprintf
46 #define atoll _atoi64
47 #define strtoll _strtoi64
48 #define strtoull _strtoui64
49 #define wcstoll _wcstoi64
50 #define wcstoull _wcstoui64
strtof(const char * nptr,char ** endptr)51 _LIBCPP_ALWAYS_INLINE float strtof(const char *nptr, char **endptr)
52 {
53 return _Stof(nptr, endptr, 0);
54 }
strtod(const char * nptr,char ** endptr)55 _LIBCPP_ALWAYS_INLINE double strtod(const char *nptr, char **endptr)
56 {
57 return _Stod(nptr, endptr, 0);
58 }
strtold(const char * nptr,char ** endptr)59 _LIBCPP_ALWAYS_INLINE long double strtold(const char *nptr, char **endptr)
60 {
61 return _Stold(nptr, endptr, 0);
62 }
63
64 #define _Exit _exit
65 #endif
66
67 #if defined(_LIBCPP_MSVC)
68
69 // Bit builtin's make these assumptions when calling _BitScanForward/Reverse
70 // etc. These assumptions are expected to be true for Win32/Win64 which this
71 // file supports.
72 static_assert(sizeof(unsigned long long) == 8, "");
73 static_assert(sizeof(unsigned long) == 4, "");
74 static_assert(sizeof(unsigned int) == 4, "");
75
__builtin_popcount(unsigned int x)76 _LIBCPP_ALWAYS_INLINE int __builtin_popcount(unsigned int x)
77 {
78 // Binary: 0101...
79 static const unsigned int m1 = 0x55555555;
80 // Binary: 00110011..
81 static const unsigned int m2 = 0x33333333;
82 // Binary: 4 zeros, 4 ones ...
83 static const unsigned int m4 = 0x0f0f0f0f;
84 // The sum of 256 to the power of 0,1,2,3...
85 static const unsigned int h01 = 0x01010101;
86 // Put count of each 2 bits into those 2 bits.
87 x -= (x >> 1) & m1;
88 // Put count of each 4 bits into those 4 bits.
89 x = (x & m2) + ((x >> 2) & m2);
90 // Put count of each 8 bits into those 8 bits.
91 x = (x + (x >> 4)) & m4;
92 // Returns left 8 bits of x + (x<<8) + (x<<16) + (x<<24).
93 return (x * h01) >> 24;
94 }
95
__builtin_popcountl(unsigned long x)96 _LIBCPP_ALWAYS_INLINE int __builtin_popcountl(unsigned long x)
97 {
98 return __builtin_popcount(static_cast<int>(x));
99 }
100
__builtin_popcountll(unsigned long long x)101 _LIBCPP_ALWAYS_INLINE int __builtin_popcountll(unsigned long long x)
102 {
103 // Binary: 0101...
104 static const unsigned long long m1 = 0x5555555555555555;
105 // Binary: 00110011..
106 static const unsigned long long m2 = 0x3333333333333333;
107 // Binary: 4 zeros, 4 ones ...
108 static const unsigned long long m4 = 0x0f0f0f0f0f0f0f0f;
109 // The sum of 256 to the power of 0,1,2,3...
110 static const unsigned long long h01 = 0x0101010101010101;
111 // Put count of each 2 bits into those 2 bits.
112 x -= (x >> 1) & m1;
113 // Put count of each 4 bits into those 4 bits.
114 x = (x & m2) + ((x >> 2) & m2);
115 // Put count of each 8 bits into those 8 bits.
116 x = (x + (x >> 4)) & m4;
117 // Returns left 8 bits of x + (x<<8) + (x<<16) + (x<<24) + ...
118 return static_cast<int>((x * h01) >> 56);
119 }
120
121 // Returns the number of trailing 0-bits in x, starting at the least significant
122 // bit position. If x is 0, the result is undefined.
__builtin_ctzll(unsigned long long mask)123 _LIBCPP_ALWAYS_INLINE int __builtin_ctzll(unsigned long long mask)
124 {
125 unsigned long where;
126 // Search from LSB to MSB for first set bit.
127 // Returns zero if no set bit is found.
128 #if defined(_WIN64)
129 if (_BitScanForward64(&where, mask))
130 return static_cast<int>(where);
131 #elif defined(_WIN32)
132 // Win32 doesn't have _BitScanForward64 so emulate it with two 32 bit calls.
133 // Scan the Low Word.
134 if (_BitScanForward(&where, static_cast<unsigned long>(mask)))
135 return static_cast<int>(where);
136 // Scan the High Word.
137 if (_BitScanForward(&where, static_cast<unsigned long>(mask >> 32)))
138 return static_cast<int>(where + 32); // Create a bit offset from the LSB.
139 #else
140 #error "Implementation of __builtin_ctzll required"
141 #endif
142 return 64;
143 }
144
__builtin_ctzl(unsigned long mask)145 _LIBCPP_ALWAYS_INLINE int __builtin_ctzl(unsigned long mask)
146 {
147 unsigned long where;
148 // Search from LSB to MSB for first set bit.
149 // Returns zero if no set bit is found.
150 if (_BitScanForward(&where, mask))
151 return static_cast<int>(where);
152 return 32;
153 }
154
__builtin_ctz(unsigned int mask)155 _LIBCPP_ALWAYS_INLINE int __builtin_ctz(unsigned int mask)
156 {
157 // Win32 and Win64 expectations.
158 static_assert(sizeof(mask) == 4, "");
159 static_assert(sizeof(unsigned long) == 4, "");
160 return __builtin_ctzl(static_cast<unsigned long>(mask));
161 }
162
163 // Returns the number of leading 0-bits in x, starting at the most significant
164 // bit position. If x is 0, the result is undefined.
__builtin_clzll(unsigned long long mask)165 _LIBCPP_ALWAYS_INLINE int __builtin_clzll(unsigned long long mask)
166 {
167 unsigned long where;
168 // BitScanReverse scans from MSB to LSB for first set bit.
169 // Returns 0 if no set bit is found.
170 #if defined(_WIN64)
171 if (_BitScanReverse64(&where, mask))
172 return static_cast<int>(63 - where);
173 #elif defined(_WIN32)
174 // Scan the high 32 bits.
175 if (_BitScanReverse(&where, static_cast<unsigned long>(mask >> 32)))
176 return static_cast<int>(63 -
177 (where + 32)); // Create a bit offset from the MSB.
178 // Scan the low 32 bits.
179 if (_BitScanReverse(&where, static_cast<unsigned long>(mask)))
180 return static_cast<int>(63 - where);
181 #else
182 #error "Implementation of __builtin_clzll required"
183 #endif
184 return 64; // Undefined Behavior.
185 }
186
__builtin_clzl(unsigned long mask)187 _LIBCPP_ALWAYS_INLINE int __builtin_clzl(unsigned long mask)
188 {
189 unsigned long where;
190 // Search from LSB to MSB for first set bit.
191 // Returns zero if no set bit is found.
192 if (_BitScanReverse(&where, mask))
193 return static_cast<int>(31 - where);
194 return 32; // Undefined Behavior.
195 }
196
__builtin_clz(unsigned int x)197 _LIBCPP_ALWAYS_INLINE int __builtin_clz(unsigned int x)
198 {
199 return __builtin_clzl(x);
200 }
201 #endif // _LIBCPP_MSVC
202
203 #endif // _LIBCPP_SUPPORT_WIN32_SUPPORT_H
204