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