43 lines
1.3 KiB
C++
43 lines
1.3 KiB
C++
#ifndef RNG_SFMT_H
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#define RNG_SFMT_H
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#include "rng_abstract.h"
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#include "sfmt/SFMT.h"
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#include <QMutex>
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#include <climits>
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/**
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* This class encapsulates a state of the art PRNG and can be used
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* to return uniformly distributed integer random numbers from a range [min, max].
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* Though technically possible, min must be >= 0 and max should always be > 0.
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* If max < 0 and min == 0 it is assumed that rand() % -max is wanted and the result will
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* be -rand(0, -max).
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* This is the only exception to the rule that !(min > max) and is actually unused in
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* Cockatrice.
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*
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* Technical details:
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* The RNG uses the SIMD-oriented Fast Mersenne Twister code v1.4.1 from
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* http://www.math.sci.hiroshima-u.ac.jp/~%20m-mat/MT/SFMT/index.html
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* The SFMT RNG creates unsigned int 64bit pseudo random numbers.
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*
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* These are mapped to values from the interval [min, max] without bias by using Knuth's
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* "Algorithm S (Selection sampling technique)" from "The Art of Computer Programming 3rd
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* Edition Volume 2 / Seminumerical Algorithms".
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*/
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class RNG_SFMT : public RNG_Abstract
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{
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Q_OBJECT
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private:
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QMutex mutex;
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sfmt_t sfmt;
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// The discrete cumulative distribution function for the RNG
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unsigned int cdf(unsigned int min, unsigned int max);
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public:
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RNG_SFMT(QObject *parent = 0);
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unsigned int rand(int min, int max);
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};
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#endif
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