src/base/random.cc

   1 /*
   2  * Copyright (c) 2003-2005 The Regents of The University of Michigan
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met: redistributions of source code must retain the above copyright
   8  * notice, this list of conditions and the following disclaimer;
   9  * redistributions in binary form must reproduce the above copyright
  10  * notice, this list of conditions and the following disclaimer in the
  11  * documentation and/or other materials provided with the distribution;
  12  * neither the name of the copyright holders nor the names of its
  13  * contributors may be used to endorse or promote products derived from
  14  * this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  17  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  18  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  19  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  20  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  21  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  22  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  26  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  */
  28
  29 #include <cstdlib>
  30 #include <cmath>
  31
  32 #include "sim/param.hh"
  33 #include "base/random.hh"
  34 #include "base/trace.hh"
  35
  36 using namespace std;
  37
  38 class RandomContext : public ParamContext
  39 {
  40   public:
  41     RandomContext(const string &_iniSection)
  42         : ::ParamContext(_iniSection) {}
  43     ~RandomContext() {}
  44
  45     void checkParams();
  46 };
  47
  48 RandomContext paramContext("random");
  49
  50 Param<unsigned>
  51 seed(&paramContext, "seed", "seed to random number generator", 1);
  52
  53 void
  54 RandomContext::checkParams()
  55 {
  56     ::srand48(seed);
  57 }
  58
  59 long
  60 getLong()
  61 {
  62     return mrand48();
  63 }
  64
  65 int64_t
  66 getUniform(int64_t min, int64_t max)
  67 {
  68     double r;
  69     r = drand48() * (max-min) + min;
  70     return (int64_t)round(r);
  71 }
  72
  73 uint64_t
  74 getUniformPos(uint64_t min, uint64_t max)
  75 {
  76     double r;
  77     r = drand48() * (max-min) + min;
  78     return (uint64_t)round(r);
  79 }
  80
  81
  82 // idea for generating a double from erand48
  83 double
  84 getDouble()
  85 {
  86     union {
  87         uint32_t _long[2];
  88         uint16_t _short[4];
  89     };
  90
  91     _long[0] = mrand48();
  92     _long[1] = mrand48();
  93
  94     return ldexp((double) _short[0], -48) +
  95         ldexp((double) _short[1], -32) +
  96         ldexp((double) _short[2], -16);
  97 }