109 lines
3.3 KiB
C++
109 lines
3.3 KiB
C++
// Copyright (c) 2013, Peter Pettersson
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice, this
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// list of conditions and the following disclaimer.
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// 2. Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
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// ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//
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// The views and conclusions contained in the software and documentation are those
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// of the authors and should not be interpreted as representing official policies,
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// either expressed or implied, of the FreeBSD Project.
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#ifndef RANDOM_WELL512A_H
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#define RANDOM_WELL512A_H
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#include <stdlib.h> // Needed for rand().
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#include <memory.h> // Needed for memcpy().
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class RandomWELL512a
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{
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public:
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RandomWELL512a(int seed);
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RandomWELL512a(unsigned *seed);
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unsigned GetUnsigned();
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double GetDouble();
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private:
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unsigned state[16];
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unsigned index;
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};
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inline RandomWELL512a::RandomWELL512a(int seed)
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: index(0)
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{
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srand(seed);
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for (int i = 0; i < 16; ++i)
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state[i] = rand();
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}
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inline RandomWELL512a::RandomWELL512a(unsigned *seed)
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: index(0)
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{
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memcpy(state, seed, 16 * sizeof(unsigned));
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}
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inline unsigned RandomWELL512a::GetUnsigned()
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{
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#define MUTATE_LEFT(value, shift) value ^ (value << shift)
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#define MUTATE_RIGHT(value, shift) value ^ (value >> shift)
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#define MUTATE_LEFT_MIX(value, shift, mix) value ^ ((value << shift) & mix)
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unsigned index_9 = (index + 9) & 15;
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unsigned index_13 = (index + 13) & 15;
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unsigned index_15 = (index + 15) & 15;
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unsigned state_index = state[index];
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unsigned state_index_9 = state[index_9];
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unsigned state_index_13 = state[index_13];
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unsigned state_index_15 = state[index_15];
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unsigned z1 = MUTATE_LEFT(state_index, 16);
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z1 ^= MUTATE_LEFT(state_index_13, 15);
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unsigned z2 = MUTATE_RIGHT(state_index_9, 11);
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unsigned result0 = z1 ^ z2;
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state[index] = result0;
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unsigned result1 = MUTATE_LEFT(state_index_15, 2);
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result1 ^= MUTATE_LEFT(z1, 18);;
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result1 ^= z2 << 28;
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result1 ^= MUTATE_LEFT_MIX(result0, 5, 0xda442d24U);
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index = index_15;
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state[index] = result1;
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return result1;
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#undef MUTATE_LEFT
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#undef MUTATE_RIGHT
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#undef MUTATE_LEFT_MIX
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}
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inline double RandomWELL512a::GetDouble()
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{
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const double kToFloat = 2.32830643653869628906e-10;
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return GetUnsigned() * kToFloat;
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}
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#endif // RANDOM_WELL512A_H
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