libstdc++-v3/src/c++11/random.cc

   1 // random -*- C++ -*-
   2
   3 // Copyright (C) 2012-2013 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.
  10
  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.
  15
  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.
  19
  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/>.
  24
  25 #include <random>
  26
  27 #ifdef  _GLIBCXX_USE_C99_STDINT_TR1
  28
  29 #if defined __i386__ || defined __x86_64__
  30 # include <cpuid.h>
  31 #endif
  32
  33 #ifdef _GLIBCXX_HAVE_UNISTD_H
  34 # include <unistd.h>
  35 #endif
  36
  37 namespace std _GLIBCXX_VISIBILITY(default)
  38 {
  39
  40   namespace
  41   {
  42     static unsigned long
  43     _M_strtoul(const std::string& __str)
  44     {
  45       unsigned long __ret = 5489UL;
  46       if (__str != "mt19937")
  47         {
  48           const char* __nptr = __str.c_str();
  49           char* __endptr;
  50           __ret = std::strtoul(__nptr, &__endptr, 0);
  51           if (*__nptr == '\0' || *__endptr != '\0')
  52             std::__throw_runtime_error(__N("random_device::_M_strtoul"
  53                                            "(const std::string&)"));
  54         }
  55       return __ret;
  56     }
  57
  58 #if (defined __i386__ || defined __x86_64__) && defined _GLIBCXX_X86_RDRAND
  59     unsigned int
  60     __attribute__ ((target("rdrnd")))
  61     __x86_rdrand(void)
  62     {
  63       unsigned int retries = 100;
  64       unsigned int val;
  65
  66       while (__builtin_ia32_rdrand32_step(&val) == 0)
  67         if (--retries == 0)
  68           std::__throw_runtime_error(__N("random_device::__x86_rdrand(void)"));
  69
  70       return val;
  71     }
  72 #endif
  73   }
  74
  75
  76   void
  77   random_device::_M_init(const std::string& token)
  78   {
  79     const char *fname = token.c_str();
  80
  81     if (token == "default")
  82       {
  83 #if (defined __i386__ || defined __x86_64__) && defined _GLIBCXX_X86_RDRAND
  84         unsigned int eax, ebx, ecx, edx;
  85         // Check availability of cpuid and, for now at least, also the
  86         // CPU signature for Intel's
  87         if (__get_cpuid_max(0, &ebx) > 0 && ebx == signature_INTEL_ebx)
  88           {
  89             __cpuid(1, eax, ebx, ecx, edx);
  90             if (ecx & bit_RDRND)
  91               {
  92                 _M_file = nullptr;
  93                 return;
  94               }
  95           }
  96 #endif
  97
  98         fname = "/dev/urandom";
  99       }
 100     else if (token != "/dev/urandom" && token != "/dev/random")
 101     fail:
 102       std::__throw_runtime_error(__N("random_device::"
 103                                      "random_device(const std::string&)"));
 104
 105     _M_file = std::fopen(fname, "rb");
 106     if (! _M_file)
 107       goto fail;
 108   }
 109
 110   void
 111   random_device::_M_init_pretr1(const std::string& token)
 112   {
 113     _M_mt.seed(_M_strtoul(token));
 114   }
 115
 116   void
 117   random_device::_M_fini()
 118   {
 119     if (_M_file)
 120       std::fclose(_M_file);
 121   }
 122
 123   random_device::result_type
 124   random_device::_M_getval()
 125   {
 126 #if (defined __i386__ || defined __x86_64__) && defined _GLIBCXX_X86_RDRAND
 127     if (! _M_file)
 128       return __x86_rdrand();
 129 #endif
 130
 131     result_type __ret;
 132 #ifdef _GLIBCXX_HAVE_UNISTD_H
 133     read(fileno(_M_file), reinterpret_cast<void*>(&__ret), sizeof(result_type));
 134 #else
 135     std::fread(reinterpret_cast<void*>(&__ret), sizeof(result_type),
 136                1, _M_file);
 137 #endif
 138     return __ret;
 139   }
 140
 141   random_device::result_type
 142   random_device::_M_getval_pretr1()
 143   {
 144     return _M_mt();
 145   }
 146
 147   template class mersenne_twister_engine<
 148     uint_fast32_t,
 149     32, 624, 397, 31,
 150     0x9908b0dfUL, 11,
 151     0xffffffffUL, 7,
 152     0x9d2c5680UL, 15,
 153     0xefc60000UL, 18, 1812433253UL>;
 154 }
 155 #endif