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1 | // Created on: 2014-07-18 |
2 | // Created by: Alexander Malyshev |
3 | // Copyright (c) 2014-2014 OPEN CASCADE SAS |
4 | // |
5 | // This file is part of Open CASCADE Technology software library. |
6 | // |
7 | // This library is free software; you can redistribute it and/or modify it under |
8 | // the terms of the GNU Lesser General Public License version 2.1 as published |
9 | // by the Free Software Foundation, with special exception defined in the file |
10 | // OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT |
11 | // distribution for complete text of the license and disclaimer of any warranty. |
12 | // |
13 | // Alternatively, this file may be used under the terms of Open CASCADE |
14 | // commercial license or contractual agreement. |
15 | |
16 | #ifndef _math_BullardGenerator_HeaderFile |
17 | #define _math_BullardGenerator_HeaderFile |
18 | |
19 | #include <Standard_Real.hxx> |
20 | |
21 | //! Fast random number generator (the algorithm proposed by Ian C. Bullard). |
22 | class math_BullardGenerator |
23 | { |
24 | public: |
25 | |
26 | //! Creates new Xorshift 64-bit RNG. |
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27 | math_BullardGenerator (unsigned int theSeed = 1) |
28 | : myStateHi (theSeed) |
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29 | { |
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30 | SetSeed (theSeed); |
31 | } |
32 | |
33 | //! Setup new seed / reset defaults. |
34 | void SetSeed (unsigned int theSeed = 1) |
35 | { |
36 | myStateHi = theSeed; |
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37 | myStateLo = theSeed ^ 0x49616E42; |
38 | } |
39 | |
40 | //! Generates new 64-bit integer value. |
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41 | unsigned int NextInt() |
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42 | { |
43 | myStateHi = (myStateHi >> 2) + (myStateHi << 2); |
44 | |
45 | myStateHi += myStateLo; |
46 | myStateLo += myStateHi; |
47 | |
48 | return myStateHi; |
49 | } |
50 | |
51 | //! Generates new floating-point value. |
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52 | Standard_Real NextReal() |
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53 | { |
54 | return NextInt() / static_cast<Standard_Real> (0xFFFFFFFFu); |
55 | } |
56 | |
57 | private: |
58 | |
59 | unsigned int myStateHi; |
60 | unsigned int myStateLo; |
61 | |
62 | }; |
63 | |
64 | #endif |