don't look for win32 directory in a package
[chaz/yoink] / src / Moof / Random.cc
1
2 /*******************************************************************************
3
4 Copyright (c) 2009, Charles McGarvey
5 All rights reserved.
6
7 Redistribution and use in source and binary forms, with or without
8 modification, are permitted provided that the following conditions are met:
9
10 * Redistributions of source code must retain the above copyright notice,
11 this list of conditions and the following disclaimer.
12 * Redistributions in binary form must reproduce the above copyright notice,
13 this list of conditions and the following disclaimer in the documentation
14 and/or other materials provided with the distribution.
15
16 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
17 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
20 FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
22 SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
23 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
25 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26
27 *******************************************************************************/
28
29 #include <climits> // ULONG_MAX
30 #include <cmath> // log
31 #include <cstdlib> // srand, rand, RAND_MAX
32 #include <ctime> // time
33
34 #include "Random.hh"
35
36
37 namespace Mf {
38
39
40 unsigned setSeed(unsigned theSeed)
41 {
42 srand(theSeed);
43 return theSeed;
44 }
45
46 unsigned setSeed()
47 {
48 return setSeed(time(0));
49 }
50
51
52 template <typename T>
53 T getRandom()
54 {
55 const float ln2 = 0.693147;
56 static const unsigned bitsPerPiece = std::log(float(RAND_MAX)) / ln2;
57 static const unsigned sizeOfType = sizeof(T) * 8;
58 static const unsigned pieces = sizeOfType / bitsPerPiece +
59 ((sizeOfType % bitsPerPiece) ? 1 : 0);
60
61 T bits = 0;
62
63 // we need to call rand() multiple times if it won't provide enough random
64 // bits to fill the size of the given type
65 for (unsigned i = 0; i < pieces; i++)
66 {
67 long piece = rand();
68 bits |= piece << (i * bitsPerPiece);
69 }
70
71 return bits;
72 }
73
74
75 template <>
76 bool getRandom<bool>()
77 {
78 return rand() % 2;
79 }
80
81 template <typename T>
82 T getRandom(T lower, T upper)
83 {
84 unsigned short randInt = getRandom<unsigned int>();
85 return lower + T(randInt % (upper - lower + 1));
86 }
87
88 template <>
89 float getRandom(float lower, float upper)
90 {
91 unsigned long randInt = getRandom<unsigned long>();
92 return (float(randInt) / float(ULONG_MAX)) * (upper - lower) + lower;
93 }
94
95 template <>
96 double getRandom(double lower, double upper)
97 {
98 unsigned long long randInt = getRandom<unsigned long long>();
99 return (double(randInt) / double(ULLONG_MAX)) * (upper - lower) + lower;
100 }
101
102 template <>
103 float getRandom()
104 {
105 return getRandom<float>(0.0, 1.0);
106 }
107
108 template <>
109 double getRandom()
110 {
111 return getRandom<double>(0.0, 1.0);
112 }
113
114
115 }; // namespace Mf
116
117 /** vim: set ts=4 sw=4 tw=80: *************************************************/
118
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