Avoid -Wattribute-alias warnings for long double compat symbols
[official-gcc.git] / libstdc++-v3 / src / c++11 / random.cc
blobef17223ac0b01fd71a4460822670e9c3a6d006f4
1 // random -*- C++ -*-
3 // Copyright (C) 2012-2017 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
25 #define _GLIBCXX_USE_CXX11_ABI 1
26 #include <random>
28 #ifdef _GLIBCXX_USE_C99_STDINT_TR1
30 #if defined __i386__ || defined __x86_64__
31 # include <cpuid.h>
32 #endif
34 #include <cerrno>
35 #include <cstdio>
37 #ifdef _GLIBCXX_HAVE_UNISTD_H
38 # include <unistd.h>
39 #endif
41 #ifdef _GLIBCXX_HAVE_SYS_IOCTL_H
42 # include <sys/ioctl.h>
43 #endif
45 #ifdef _GLIBCXX_HAVE_LINUX_RANDOM_H
46 # include <linux/random.h>
47 #endif
49 namespace std _GLIBCXX_VISIBILITY(default)
51 namespace
53 static unsigned long
54 _M_strtoul(const std::string& __str)
56 unsigned long __ret = 5489UL;
57 if (__str != "mt19937")
59 const char* __nptr = __str.c_str();
60 char* __endptr;
61 __ret = std::strtoul(__nptr, &__endptr, 0);
62 if (*__nptr == '\0' || *__endptr != '\0')
63 std::__throw_runtime_error(__N("random_device::_M_strtoul"
64 "(const std::string&)"));
66 return __ret;
69 #if (defined __i386__ || defined __x86_64__) && defined _GLIBCXX_X86_RDRAND
70 unsigned int
71 __attribute__ ((target("rdrnd")))
72 __x86_rdrand(void)
74 unsigned int retries = 100;
75 unsigned int val;
77 while (__builtin_ia32_rdrand32_step(&val) == 0)
78 if (--retries == 0)
79 std::__throw_runtime_error(__N("random_device::__x86_rdrand(void)"));
81 return val;
83 #endif
86 void
87 random_device::_M_init(const std::string& token)
89 const char *fname = token.c_str();
91 if (token == "default")
93 #if (defined __i386__ || defined __x86_64__) && defined _GLIBCXX_X86_RDRAND
94 unsigned int eax, ebx, ecx, edx;
95 // Check availability of cpuid and, for now at least, also the
96 // CPU signature for Intel's
97 if (__get_cpuid_max(0, &ebx) > 0 && ebx == signature_INTEL_ebx)
99 __cpuid(1, eax, ebx, ecx, edx);
100 if (ecx & bit_RDRND)
102 _M_file = nullptr;
103 return;
106 #endif
108 fname = "/dev/urandom";
110 else if (token != "/dev/urandom" && token != "/dev/random")
111 fail:
112 std::__throw_runtime_error(__N("random_device::"
113 "random_device(const std::string&)"));
115 _M_file = static_cast<void*>(std::fopen(fname, "rb"));
116 if (!_M_file)
117 goto fail;
120 void
121 random_device::_M_init_pretr1(const std::string& token)
123 _M_mt.seed(_M_strtoul(token));
126 void
127 random_device::_M_fini()
129 if (_M_file)
130 std::fclose(static_cast<FILE*>(_M_file));
133 random_device::result_type
134 random_device::_M_getval()
136 #if (defined __i386__ || defined __x86_64__) && defined _GLIBCXX_X86_RDRAND
137 if (!_M_file)
138 return __x86_rdrand();
139 #endif
141 result_type __ret;
142 void* p = &__ret;
143 size_t n = sizeof(result_type);
144 #ifdef _GLIBCXX_HAVE_UNISTD_H
147 const int e = read(fileno(static_cast<FILE*>(_M_file)), p, n);
148 if (e > 0)
150 n -= e;
151 p = static_cast<char*>(p) + e;
153 else if (e != -1 || errno != EINTR)
154 __throw_runtime_error(__N("random_device could not be read"));
156 while (n > 0);
157 #else
158 const size_t e = std::fread(p, n, 1, static_cast<FILE*>(_M_file));
159 if (e != 1)
160 __throw_runtime_error(__N("random_device could not be read"));
161 #endif
163 return __ret;
166 random_device::result_type
167 random_device::_M_getval_pretr1()
169 return _M_mt();
172 double
173 random_device::_M_getentropy() const noexcept
175 #if defined _GLIBCXX_HAVE_SYS_IOCTL_H && defined RNDGETENTCNT
176 if (!_M_file)
177 return 0.0;
179 const int fd = fileno(static_cast<FILE*>(_M_file));
180 if (fd < 0)
181 return 0.0;
183 int ent;
184 if (ioctl(fd, RNDGETENTCNT, &ent) < 0)
185 return 0.0;
187 if (ent < 0)
188 return 0.0;
190 const int max = sizeof(result_type) * __CHAR_BIT__;
191 if (ent > max)
192 ent = max;
194 return static_cast<double>(ent);
195 #else
196 return 0.0;
197 #endif
200 template class mersenne_twister_engine<
201 uint_fast32_t,
202 32, 624, 397, 31,
203 0x9908b0dfUL, 11,
204 0xffffffffUL, 7,
205 0x9d2c5680UL, 15,
206 0xefc60000UL, 18, 1812433253UL>;
208 #endif