libstdc++-v3/testsuite/util/rng/twister_rand_gen.cc

   1 // -*- C++ -*-
   2
   3 // Copyright (C) 2005, 2006 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 terms
   7 // of the GNU General Public License as published by the Free Software
   8 // Foundation; either version 2, or (at your option) any later
   9 // version.
  10
  11 // This library is distributed in the hope that it will be useful, but
  12 // WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 // General Public License for more details.
  15
  16 // You should have received a copy of the GNU General Public License along
  17 // with this library; see the file COPYING.  If not, write to the Free
  18 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  19 // USA.
  20
  21 // As a special exception, you may use this file as part of a free
  22 // software library without restriction.  Specifically, if other files
  23 // instantiate templates or use macros or inline functions from this
  24 // file, or you compile this file and link it with other files to
  25 // produce an executable, this file does not by itself cause the
  26 // resulting executable to be covered by the GNU General Public
  27 // License.  This exception does not however invalidate any other
  28 // reasons why the executable file might be covered by the GNU General
  29 // Public License.
  30
  31 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
  32
  33 // Permission to use, copy, modify, sell, and distribute this software
  34 // is hereby granted without fee, provided that the above copyright
  35 // notice appears in all copies, and that both that copyright notice
  36 // and this permission notice appear in supporting documentation. None
  37 // of the above authors, nor IBM Haifa Research Laboratories, make any
  38 // representation about the suitability of this software for any
  39 // purpose. It is provided "as is" without express or implied
  40 // warranty.
  41
  42 /**
  43  * @file twister_rand_gen.cc
  44  */
  45
  46 #include <util/rng/twister_rand_gen.hpp>
  47 #include <ctime>
  48
  49 namespace pb_ds
  50 {
  51   namespace test
  52   {
  53 #ifdef PB_DS_TWISTER_RAND_GEN_DEBUG
  54 #define PB_DS_DBG_ASSERT(X) assert(X)
  55 #define PB_DS_DBG_VERIFY(X) assert(X)
  56 #define PB_DS_DBG_ONLY(X) X
  57 #else // #ifdef PB_DS_TWISTER_RAND_GEN_DEBUG
  58 #define PB_DS_DBG_ASSERT(X)
  59 #define PB_DS_DBG_VERIFY(X) {if((X)==0);}
  60 #define PB_DS_DBG_ONLY(X) ;
  61 #endif // #ifdef PB_DS_TWISTER_RAND_GEN_DEBUG
  62
  63     twister_rand_gen::
  64     twister_rand_gen(unsigned int seed)
  65     : m_base_generator(seed)
  66     {
  67       // Do nothing.
  68     }
  69
  70     void
  71     twister_rand_gen::
  72     init(unsigned int seed)
  73     { m_base_generator.seed(seed); }
  74
  75     unsigned long
  76     twister_rand_gen::
  77     get_unsigned_long(unsigned long min, unsigned long max)
  78     {
  79       PB_DS_DBG_ASSERT(max >= min);
  80
  81       const double prob = get_prob();
  82
  83       const unsigned long rand_word =
  84         (unsigned long)((max - min + 1) * prob) + min;
  85
  86       PB_DS_DBG_ASSERT(rand_word <= max);
  87
  88       return rand_word;
  89     }
  90
  91     double
  92     twister_rand_gen::
  93     get_prob()
  94     {
  95       const double eng_min = m_base_generator.min();
  96       const double eng_range =
  97         static_cast<const double>(m_base_generator.max() - eng_min);
  98
  99       const double eng_res =
 100         static_cast<const double>(m_base_generator() - eng_min);
 101
 102       const double ret = eng_res / eng_range;
 103
 104       PB_DS_DBG_ASSERT(ret >=0 && ret <= 1);
 105
 106       return ret;
 107     }
 108
 109 #undef PB_DS_DBG_ASSERT
 110 #undef PB_DS_DBG_VERIFY
 111 #undef PB_DS_DBG_ONLY
 112   } // namespace test
 113 } // namespace pb_ds