random.cc revision 1954 
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
36using namespace std;
37
38class RandomContext : public ParamContext
39{
40  public:
41    RandomContext(const string &_iniSection)
42        : ::ParamContext(_iniSection) {}
43    ~RandomContext() {}
44
45    void checkParams();
46};
47
48RandomContext paramContext("random");
49
50Param<unsigned>
51seed(&paramContext, "seed", "seed to random number generator", 1);
52
53void
54RandomContext::checkParams()
55{
56    ::srand48(seed);
57}
58
59long
60getLong()
61{
62    return mrand48();
63}
64
65int64_t
66getUniform(int64_t maxmin)
67{
68    double r;
69    r = (drand48() - 0.500) * 2 * maxmin;
70    DPRINTFN("getUniform %f\n", r);
71    return (int64_t)round(r);
72}
73
74uint64_t
75getUniformPos(uint64_t max)
76{
77    double r;
78    r = drand48() * 2 * max;
79    return (uint64_t)round(r);
80}
81
82
83// idea for generating a double from erand48
84double
85getDouble()
86{
87    union {
88        uint32_t _long[2];
89        uint16_t _short[4];
90    };
91
92    _long[0] = mrand48();
93    _long[1] = mrand48();
94
95    return ldexp((double) _short[0], -48) +
96        ldexp((double) _short[1], -32) +
97        ldexp((double) _short[2], -16);
98}
99