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

   1 // random -*- C++ -*-
   2
   3 // Copyright (C) 2012-2014 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 #define _GLIBCXX_USE_CXX11_ABI 1
  26 #include <random>
  27
  28 #ifdef  _GLIBCXX_USE_C99_STDINT_TR1
  29
  30 #if defined __i386__ || defined __x86_64__
  31 # include <cpuid.h>
  32 #endif
  33
  34 #include <cstdio>
  35
  36 #ifdef _GLIBCXX_HAVE_UNISTD_H
  37 # include <unistd.h>
  38 #endif
  39
  40 namespace std _GLIBCXX_VISIBILITY(default)
  41 {
  42   namespace
  43   {
  44     static unsigned long
  45     _M_strtoul(const std::string& __str)
  46     {
  47       unsigned long __ret = 5489UL;
  48       if (__str != "mt19937")
  49         {
  50           const char* __nptr = __str.c_str();
  51           char* __endptr;
  52           __ret = std::strtoul(__nptr, &__endptr, 0);
  53           if (*__nptr == '\0' || *__endptr != '\0')
  54             std::__throw_runtime_error(__N("random_device::_M_strtoul"
  55                                            "(const std::string&)"));
  56         }
  57       return __ret;
  58     }
  59
  60 #if (defined __i386__ || defined __x86_64__) && defined _GLIBCXX_X86_RDRAND
  61     unsigned int
  62     __attribute__ ((target("rdrnd")))
  63     __x86_rdrand(void)
  64     {
  65       unsigned int retries = 100;
  66       unsigned int val;
  67
  68       while (__builtin_ia32_rdrand32_step(&val) == 0)
  69         if (--retries == 0)
  70           std::__throw_runtime_error(__N("random_device::__x86_rdrand(void)"));
  71
  72       return val;
  73     }
  74 #endif
  75   }
  76
  77   void
  78   random_device::_M_init(const std::string& token)
  79   {
  80     const char *fname = token.c_str();
  81
  82     if (token == "default")
  83       {
  84 #if (defined __i386__ || defined __x86_64__) && defined _GLIBCXX_X86_RDRAND
  85         unsigned int eax, ebx, ecx, edx;
  86         // Check availability of cpuid and, for now at least, also the
  87         // CPU signature for Intel's
  88         if (__get_cpuid_max(0, &ebx) > 0 && ebx == signature_INTEL_ebx)
  89           {
  90             __cpuid(1, eax, ebx, ecx, edx);
  91             if (ecx & bit_RDRND)
  92               {
  93                 _M_file = nullptr;
  94                 return;
  95               }
  96           }
  97 #endif
  98
  99         fname = "/dev/urandom";
 100       }
 101     else if (token != "/dev/urandom" && token != "/dev/random")
 102     fail:
 103       std::__throw_runtime_error(__N("random_device::"
 104                                      "random_device(const std::string&)"));
 105
 106     _M_file = static_cast<void*>(std::fopen(fname, "rb"));
 107     if (!_M_file)
 108       goto fail;
 109   }
 110
 111   void
 112   random_device::_M_init_pretr1(const std::string& token)
 113   {
 114     _M_mt.seed(_M_strtoul(token));
 115   }
 116
 117   void
 118   random_device::_M_fini()
 119   {
 120     if (_M_file)
 121       std::fclose(static_cast<FILE*>(_M_file));
 122   }
 123
 124   random_device::result_type
 125   random_device::_M_getval()
 126   {
 127 #if (defined __i386__ || defined __x86_64__) && defined _GLIBCXX_X86_RDRAND
 128     if (!_M_file)
 129       return __x86_rdrand();
 130 #endif
 131
 132     result_type __ret;
 133 #ifdef _GLIBCXX_HAVE_UNISTD_H
 134     read(fileno(static_cast<FILE*>(_M_file)),
 135          static_cast<void*>(&__ret), sizeof(result_type));
 136 #else
 137     std::fread(static_cast<void*>(&__ret), sizeof(result_type),
 138                1, static_cast<FILE*>(_M_file));
 139 #endif
 140     return __ret;
 141   }
 142
 143   random_device::result_type
 144   random_device::_M_getval_pretr1()
 145   {
 146     return _M_mt();
 147   }
 148
 149   template class mersenne_twister_engine<
 150     uint_fast32_t,
 151     32, 624, 397, 31,
 152     0x9908b0dfUL, 11,
 153     0xffffffffUL, 7,
 154     0x9d2c5680UL, 15,
 155     0xefc60000UL, 18, 1812433253UL>;
 156 }
 157 #endif