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 // The mingw headers already define these as static.
35 #ifndef __MINGW32__
36 extern "C" {
37
38 int vasprintf(char **sptr, const char *__restrict fmt, va_list ap);
39 int asprintf(char **sptr, const char *__restrict fmt, ...);
40 size_t mbsnrtowcs(wchar_t *__restrict dst, const char **__restrict src,
41 size_t nmc, size_t len, mbstate_t *__restrict ps);
42 size_t wcsnrtombs(char *__restrict dst, const wchar_t **__restrict src,
43 size_t nwc, size_t len, mbstate_t *__restrict ps);
44 }
45 #endif // __MINGW32__
46
47 #if defined(_LIBCPP_MSVCRT)
48 #define snprintf _snprintf
49 #define atoll _atoi64
50 #define strtoll _strtoi64
51 #define strtoull _strtoui64
52 #define wcstoll _wcstoi64
53 #define wcstoull _wcstoui64
strtof(const char * nptr,char ** endptr)54 _LIBCPP_ALWAYS_INLINE float strtof(const char *nptr, char **endptr)
55 {
56 return _Stof(nptr, endptr, 0);
57 }
strtod(const char * nptr,char ** endptr)58 _LIBCPP_ALWAYS_INLINE double strtod(const char *nptr, char **endptr)
59 {
60 return _Stod(nptr, endptr, 0);
61 }
strtold(const char * nptr,char ** endptr)62 _LIBCPP_ALWAYS_INLINE long double strtold(const char *nptr, char **endptr)
63 {
64 return _Stold(nptr, endptr, 0);
65 }
66
67 #define _Exit _exit
68 #endif
69
70 #if defined(_LIBCPP_MSVC)
71
72 // Bit builtin's make these assumptions when calling _BitScanForward/Reverse
73 // etc. These assumptions are expected to be true for Win32/Win64 which this
74 // file supports.
75 static_assert(sizeof(unsigned long long) == 8, "");
76 static_assert(sizeof(unsigned long) == 4, "");
77 static_assert(sizeof(unsigned int) == 4, "");
78
__builtin_popcount(unsigned int x)79 _LIBCPP_ALWAYS_INLINE int __builtin_popcount(unsigned int x)
80 {
81 // Binary: 0101...
82 static const unsigned int m1 = 0x55555555;
83 // Binary: 00110011..
84 static const unsigned int m2 = 0x33333333;
85 // Binary: 4 zeros, 4 ones ...
86 static const unsigned int m4 = 0x0f0f0f0f;
87 // The sum of 256 to the power of 0,1,2,3...
88 static const unsigned int h01 = 0x01010101;
89 // Put count of each 2 bits into those 2 bits.
90 x -= (x >> 1) & m1;
91 // Put count of each 4 bits into those 4 bits.
92 x = (x & m2) + ((x >> 2) & m2);
93 // Put count of each 8 bits into those 8 bits.
94 x = (x + (x >> 4)) & m4;
95 // Returns left 8 bits of x + (x<<8) + (x<<16) + (x<<24).
96 return (x * h01) >> 24;
97 }
98
__builtin_popcountl(unsigned long x)99 _LIBCPP_ALWAYS_INLINE int __builtin_popcountl(unsigned long x)
100 {
101 return __builtin_popcount(static_cast<int>(x));
102 }
103
__builtin_popcountll(unsigned long long x)104 _LIBCPP_ALWAYS_INLINE int __builtin_popcountll(unsigned long long x)
105 {
106 // Binary: 0101...
107 static const unsigned long long m1 = 0x5555555555555555;
108 // Binary: 00110011..
109 static const unsigned long long m2 = 0x3333333333333333;
110 // Binary: 4 zeros, 4 ones ...
111 static const unsigned long long m4 = 0x0f0f0f0f0f0f0f0f;
112 // The sum of 256 to the power of 0,1,2,3...
113 static const unsigned long long h01 = 0x0101010101010101;
114 // Put count of each 2 bits into those 2 bits.
115 x -= (x >> 1) & m1;
116 // Put count of each 4 bits into those 4 bits.
117 x = (x & m2) + ((x >> 2) & m2);
118 // Put count of each 8 bits into those 8 bits.
119 x = (x + (x >> 4)) & m4;
120 // Returns left 8 bits of x + (x<<8) + (x<<16) + (x<<24) + ...
121 return static_cast<int>((x * h01) >> 56);
122 }
123
124 // Returns the number of trailing 0-bits in x, starting at the least significant
125 // bit position. If x is 0, the result is undefined.
__builtin_ctzll(unsigned long long mask)126 _LIBCPP_ALWAYS_INLINE int __builtin_ctzll(unsigned long long mask)
127 {
128 unsigned long where;
129 // Search from LSB to MSB for first set bit.
130 // Returns zero if no set bit is found.
131 #if defined(_WIN64)
132 if (_BitScanForward64(&where, mask))
133 return static_cast<int>(where);
134 #elif defined(_WIN32)
135 // Win32 doesn't have _BitScanForward64 so emulate it with two 32 bit calls.
136 // Scan the Low Word.
137 if (_BitScanForward(&where, static_cast<unsigned long>(mask)))
138 return static_cast<int>(where);
139 // Scan the High Word.
140 if (_BitScanForward(&where, static_cast<unsigned long>(mask >> 32)))
141 return static_cast<int>(where + 32); // Create a bit offset from the LSB.
142 #else
143 #error "Implementation of __builtin_ctzll required"
144 #endif
145 return 64;
146 }
147
__builtin_ctzl(unsigned long mask)148 _LIBCPP_ALWAYS_INLINE int __builtin_ctzl(unsigned long mask)
149 {
150 unsigned long where;
151 // Search from LSB to MSB for first set bit.
152 // Returns zero if no set bit is found.
153 if (_BitScanForward(&where, mask))
154 return static_cast<int>(where);
155 return 32;
156 }
157
__builtin_ctz(unsigned int mask)158 _LIBCPP_ALWAYS_INLINE int __builtin_ctz(unsigned int mask)
159 {
160 // Win32 and Win64 expectations.
161 static_assert(sizeof(mask) == 4, "");
162 static_assert(sizeof(unsigned long) == 4, "");
163 return __builtin_ctzl(static_cast<unsigned long>(mask));
164 }
165
166 // Returns the number of leading 0-bits in x, starting at the most significant
167 // bit position. If x is 0, the result is undefined.
__builtin_clzll(unsigned long long mask)168 _LIBCPP_ALWAYS_INLINE int __builtin_clzll(unsigned long long mask)
169 {
170 unsigned long where;
171 // BitScanReverse scans from MSB to LSB for first set bit.
172 // Returns 0 if no set bit is found.
173 #if defined(_WIN64)
174 if (_BitScanReverse64(&where, mask))
175 return static_cast<int>(63 - where);
176 #elif defined(_WIN32)
177 // Scan the high 32 bits.
178 if (_BitScanReverse(&where, static_cast<unsigned long>(mask >> 32)))
179 return static_cast<int>(63 -
180 (where + 32)); // Create a bit offset from the MSB.
181 // Scan the low 32 bits.
182 if (_BitScanReverse(&where, static_cast<unsigned long>(mask)))
183 return static_cast<int>(63 - where);
184 #else
185 #error "Implementation of __builtin_clzll required"
186 #endif
187 return 64; // Undefined Behavior.
188 }
189
__builtin_clzl(unsigned long mask)190 _LIBCPP_ALWAYS_INLINE int __builtin_clzl(unsigned long mask)
191 {
192 unsigned long where;
193 // Search from LSB to MSB for first set bit.
194 // Returns zero if no set bit is found.
195 if (_BitScanReverse(&where, mask))
196 return static_cast<int>(31 - where);
197 return 32; // Undefined Behavior.
198 }
199
__builtin_clz(unsigned int x)200 _LIBCPP_ALWAYS_INLINE int __builtin_clz(unsigned int x)
201 {
202 return __builtin_clzl(x);
203 }
204 #endif // _LIBCPP_MSVC
205
206 #endif // _LIBCPP_SUPPORT_WIN32_SUPPORT_H
207