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;

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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 "base/fenv.hh"
33#include "base/intmath.hh"
34#include "base/misc.hh"
35#include "base/random.hh"
36#include "sim/serialize.hh"
37
38using namespace std;
39
40Random::Random()
41{
42 // default random seed taken from original source
43 init(5489);
44}
45
46Random::Random(uint32_t s)
47{
48 init(s);
49}
50
51Random::Random(uint32_t init_key[], int key_length)
52{
53 init(init_key, key_length);
54}
55
56Random::~Random()
57{
58}
59
60// To preserve the uniform random distribution between min and max,
61// and allow all numbers to be represented, we generate a uniform
62// random number to the nearest power of two greater than max. If
63// this number doesn't fall between 0 and max, we try again. Anything
64// else would skew the distribution.
65uint32_t
66Random::genrand(uint32_t max)
67{
68 int log = ceilLog2(max);
69 int shift = (sizeof(uint32_t) * 8 - log);
70 uint32_t random;
71
72 do {
73 random = genrand() >> shift;
74 } while (random > max);
75
76 return random;
77}
78
79uint64_t
80Random::genrand(uint64_t max)
81{
82 int log = ceilLog2(max);
83 int shift = (sizeof(uint64_t) * 8 - log);
84 uint64_t random;
85
86 do {
87 random = (uint64_t)genrand() << 32 | (uint64_t)genrand();
88 random = random >> shift;
89 } while (random > max);
90
91 return random;
92}
93
94void
95Random::serialize(const string &base, ostream &os)
96{
97 int length = N;
98 paramOut(os, base + ".mti", mti);
99 paramOut(os, base + ".length", length);
100 arrayParamOut(os, base + ".data", mt, length);
101}
102
103void
104Random::unserialize(const string &base, Checkpoint *cp, const string &section)
105{
106 int length;
107
108 paramIn(cp, section, base + ".mti", mti);
109 paramIn(cp, section, base + ".length", length);
110 if (length != N)
111 panic("cant unserialize random number data. length != %d\n", length);
112
113 arrayParamIn(cp, section, base + ".data", mt, length);
114}
115
116Random random_mt;