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  * Authors: Nathan Binkert
  29  *          Ali Saidi
  30  */
  31
  32 #include <cstdlib>
  33 #include <cmath>
  34
  35 #include "sim/param.hh"
  36 #include "base/random.hh"
  37 #include "base/trace.hh"
  38
  39 using namespace std;
  40
  41 class RandomContext : public ParamContext
  42 {
  43   public:
  44     RandomContext(const string &_iniSection)
  45         : ::ParamContext(_iniSection) {}
  46     ~RandomContext() {}
  47
  48     void checkParams();
  49 };
  50
  51 RandomContext paramContext("random");
  52
  53 Param<unsigned>
  54 seed(&paramContext, "seed", "seed to random number generator", 1);
  55
  56 void
  57 RandomContext::checkParams()
  58 {
  59     ::srand48(seed);
  60 }
  61
  62 long
  63 getLong()
  64 {
  65     return mrand48();
  66 }
  67
  68 int64_t
  69 getUniform(int64_t min, int64_t max)
  70 {
  71     double r;
  72     r = drand48() * (max-min) + min;
  73     return (int64_t)round(r);
  74 }
  75
  76 uint64_t
  77 getUniformPos(uint64_t min, uint64_t max)
  78 {
  79     double r;
  80     r = drand48() * (max-min) + min;
  81     return (uint64_t)round(r);
  82 }
  83
  84
  85 // idea for generating a double from erand48
  86 double
  87 getDouble()
  88 {
  89     union {
  90         uint32_t _long[2];
  91         uint16_t _short[4];
  92     };
  93
  94     _long[0] = mrand48();
  95     _long[1] = mrand48();
  96
  97     return ldexp((double) _short[0], -48) +
  98         ldexp((double) _short[1], -32) +
  99         ldexp((double) _short[2], -16);
 100 }