random.cc revision 2665:a124942bacb8 
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
39using namespace std;
40
41class RandomContext : public ParamContext
42{
43  public:
44    RandomContext(const string &_iniSection)
45        : ::ParamContext(_iniSection) {}
46    ~RandomContext() {}
47
48    void checkParams();
49};
50
51RandomContext paramContext("random");
52
53Param<unsigned>
54seed(&paramContext, "seed", "seed to random number generator", 1);
55
56void
57RandomContext::checkParams()
58{
59    ::srand48(seed);
60}
61
62long
63getLong()
64{
65    return mrand48();
66}
67
68int64_t
69getUniform(int64_t min, int64_t max)
70{
71    double r;
72    r = drand48() * (max-min) + min;
73    return (int64_t)round(r);
74}
75
76uint64_t
77getUniformPos(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
86double
87getDouble()
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}
101