1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
|
// BEGIN_COPYRIGHT
//
// Copyright (C) 1999 Allen Akin All Rights Reserved.
//
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without
// restriction, including without limitation the rights to use,
// copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following
// conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the
// Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
// KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
// WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL ALLEN AKIN BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
// AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
// OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//
// END_COPYRIGHT
// rand.h: Simple random sequence generation utilities.
// We provide these to eliminate dependencies on the operating
// system's random number generator. This makes it possible to
// compare results for a given graphics device running under different
// operating systems.
// Based on Numerical Recipes, 2d ed., p. 284.
#ifndef __rand_h__
#define __rand_h__
namespace GLEAN {
///////////////////////////////////////////////////////////////////////////////
// RandomBase: Quick-and-dirty linear congruential generator that serves as
// a base for other random-sequence classes.
///////////////////////////////////////////////////////////////////////////////
class RandomBase {
unsigned int i;
public:
inline RandomBase(unsigned int seed): i(seed) { }
inline RandomBase(): i(1) { }
inline unsigned int next() {
i = 1664525 * i + 1013904223;
return i;
}
}; // class RandomBase
///////////////////////////////////////////////////////////////////////////////
// RandomBits: Returns a given number of random bits (expressed as an unsigned
// int, so the maximum portable number of bits is 32).
///////////////////////////////////////////////////////////////////////////////
class RandomBits: public RandomBase {
unsigned int shift;
public:
inline RandomBits(unsigned int bits, unsigned int seed):
RandomBase(seed), shift(32 - bits) { }
inline RandomBits(unsigned int bits):
RandomBase(), shift(32 - bits) { }
inline unsigned int next() { return RandomBase::next() >> shift; }
}; // class RandomBits
///////////////////////////////////////////////////////////////////////////////
// RandomSignedBits: Returns a given number of random bits (expressed as a
// signed int, so the maximum portable number of bits is 32 including sign).
///////////////////////////////////////////////////////////////////////////////
class RandomSignedBits: public RandomBase {
unsigned int shift;
public:
inline RandomSignedBits(unsigned int bits, unsigned int seed):
RandomBase(seed), shift(32 - bits) { }
inline RandomSignedBits(unsigned int bits):
RandomBase(), shift(32 - bits) { }
inline int next() {
return static_cast<int>(RandomBase::next()) >> shift;
}
}; // class RandomSignedBits
///////////////////////////////////////////////////////////////////////////////
// RandomDouble: Returns a random floating-point value in the closed
// interval [0.0, 1.0].
///////////////////////////////////////////////////////////////////////////////
class RandomDouble: public RandomBase {
public:
inline RandomDouble(unsigned int seed): RandomBase(seed) { }
inline RandomDouble(): RandomBase() { }
inline double next() {
return static_cast<double>(RandomBase::next()) / 4294967295.0;
}
}; // class RandomDouble
///////////////////////////////////////////////////////////////////////////////
// RandomBitsDouble: Returns a random floating-point value in the closed
// interval [0.0, 1.0], but with possible values limited by a generator
// returning a specific number of bits.
///////////////////////////////////////////////////////////////////////////////
class RandomBitsDouble: public RandomBits {
double scale;
public:
inline RandomBitsDouble(unsigned int bits, unsigned int seed):
RandomBits(bits, seed) { scale = (1 << bits) - 1.0; }
inline RandomBitsDouble(unsigned int bits):
RandomBits(bits) { scale = (1 << bits) - 1.0; }
inline double next() {
return static_cast<double>(RandomBits::next()) / scale;
}
}; // class RandomBitsDouble
} // namespace GLEAN
#endif // __rand_h__
|
