2 //===----------------------- support/win32/support.h ----------------------===//
4 // The LLVM Compiler Infrastructure
6 // This file is dual licensed under the MIT and the University of Illinois Open
7 // Source Licenses. See LICENSE.TXT for details.
9 //===----------------------------------------------------------------------===//
11 #ifndef _LIBCPP_SUPPORT_WIN32_SUPPORT_H
12 #define _LIBCPP_SUPPORT_WIN32_SUPPORT_H
14 // Functions and constants used in libc++ that
15 // are missing from the Windows C library.
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)
24 #if defined(_LIBCPP_MSVCRT)
27 #define swprintf _snwprintf
28 #define vswprintf _vsnwprintf
34 // The mingw headers already define these as static.
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);
47 #if defined(_LIBCPP_MSVCRT)
48 #define snprintf _snprintf
50 #define strtoll _strtoi64
51 #define strtoull _strtoui64
52 #define wcstoll _wcstoi64
53 #define wcstoull _wcstoui64
54 _LIBCPP_ALWAYS_INLINE float strtof(const char *nptr, char **endptr)
56 return _Stof(nptr, endptr, 0);
58 _LIBCPP_ALWAYS_INLINE double strtod(const char *nptr, char **endptr)
60 return _Stod(nptr, endptr, 0);
62 _LIBCPP_ALWAYS_INLINE long double strtold(const char *nptr, char **endptr)
64 return _Stold(nptr, endptr, 0);
70 #if defined(_LIBCPP_MSVC)
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
75 static_assert(sizeof(unsigned long long) == 8, "");
76 static_assert(sizeof(unsigned long) == 4, "");
77 static_assert(sizeof(unsigned int) == 4, "");
79 _LIBCPP_ALWAYS_INLINE int __builtin_popcount(unsigned int x)
82 static const unsigned int m1 = 0x55555555;
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.
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;
99 _LIBCPP_ALWAYS_INLINE int __builtin_popcountl(unsigned long x)
101 return __builtin_popcount(static_cast<int>(x));
104 _LIBCPP_ALWAYS_INLINE int __builtin_popcountll(unsigned long long x)
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.
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);
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.
126 _LIBCPP_ALWAYS_INLINE int __builtin_ctzll(unsigned long long mask)
129 // Search from LSB to MSB for first set bit.
130 // Returns zero if no set bit is found.
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.
143 #error "Implementation of __builtin_ctzll required"
148 _LIBCPP_ALWAYS_INLINE int __builtin_ctzl(unsigned long mask)
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);
158 _LIBCPP_ALWAYS_INLINE int __builtin_ctz(unsigned int mask)
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));
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.
168 _LIBCPP_ALWAYS_INLINE int __builtin_clzll(unsigned long long mask)
171 // BitScanReverse scans from MSB to LSB for first set bit.
172 // Returns 0 if no set bit is found.
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);
185 #error "Implementation of __builtin_clzll required"
187 return 64; // Undefined Behavior.
190 _LIBCPP_ALWAYS_INLINE int __builtin_clzl(unsigned long mask)
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.
200 _LIBCPP_ALWAYS_INLINE int __builtin_clz(unsigned int x)
202 return __builtin_clzl(x);
204 #endif // _LIBCPP_MSVC
206 #endif // _LIBCPP_SUPPORT_WIN32_SUPPORT_H