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DependentExtensions/cat/rand/MersenneTwister.hpp

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+/*
+	Copyright (c) 2009-2010 Christopher A. Taylor.  All rights reserved.
+
+	Redistribution and use in source and binary forms, with or without
+	modification, are permitted provided that the following conditions are met:
+
+	* Redistributions of source code must retain the above copyright notice,
+	  this list of conditions and the following disclaimer.
+	* Redistributions in binary form must reproduce the above copyright notice,
+	  this list of conditions and the following disclaimer in the documentation
+	  and/or other materials provided with the distribution.
+	* Neither the name of LibCat nor the names of its contributors may be used
+	  to endorse or promote products derived from this software without
+	  specific prior written permission.
+
+	THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+	AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+	IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+	ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+	LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+	CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+	SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+	INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+	CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+	ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+	POSSIBILITY OF SUCH DAMAGE.
+*/
+
+/*
+    Algorithm by Makoto Matsumoto
+    http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
+*/
+
+#ifndef CAT_MERSENNE_TWISTER_HPP
+#define CAT_MERSENNE_TWISTER_HPP
+
+#include <cat/rand/IRandom.hpp>
+
+namespace cat {
+
+
+// Noncryptographic pseudo-random number generator
+class MersenneTwister : public IRandom
+{
+    static const u32 MEXP = 19937;
+    static const u32 N128 = MEXP/128 + 1;
+    static const u32 N64 = N128 * 2;
+    static const u32 N32 = N128 * 4;
+    static const u32 POS1 = 122;
+    static const u32 SL1 = 18;
+    static const u32 SL2 = 1;
+    static const u32 SL2BITS = SL2*8;
+    static const u32 SR1 = 11;
+    static const u32 SR2 = 1;
+    static const u32 SR2BITS = SR2*8;
+    static const u32 MSK1 = 0xdfffffefU;
+    static const u32 MSK2 = 0xddfecb7fU;
+    static const u32 MSK3 = 0xbffaffffU;
+    static const u32 MSK4 = 0xbffffff6U;
+
+    struct MT128 {
+        u32 u[4];
+    };
+
+    MT128 state[19937/128 + 1];
+    u32 *state32;
+    u32 used;
+
+    CAT_INLINE void shiftLeft128(MT128 *r, MT128 *n, u32 bits);
+    CAT_INLINE void shiftRight128(MT128 *r, MT128 *n, u32 bits);
+
+    void enforcePeriod(); // make corrections to ensure that the generator has the full period
+    void round(MT128 *a, MT128 *b, MT128 *c, MT128 *d); // a = MTMIX(a,b,c,d)
+    void update(); // permute the existing state into a new one
+
+public:
+    MersenneTwister();
+
+    bool Initialize(u32 seed);
+    bool Initialize(u32 *seeds, u32 words);
+    bool Initialize();
+
+    u32 Generate(); // generate a 32-bit number
+    void Generate(void *buffer, int bytes); // generate a series of random numbers
+};
+
+
+} // namespace cat
+
+#endif // CAT_MERSENNE_TWISTER_HPP