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75 lines
2.3 KiB
C++
75 lines
2.3 KiB
C++
/*
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* Copyright (c) Contributors to the Open 3D Engine Project
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*
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* SPDX-License-Identifier: Apache-2.0 OR MIT
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*
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*/
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// Description : Marsenne Twister PRNG. See MT.h for more info.
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#include "MTPseudoRandom.h"
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// non-inline function definitions and static member definitions cannot
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// reside in header file because of the risk of multiple declarations
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void CMTRand_int32::gen_state() // generate new m_nState vector
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{
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for (int i = 0; i < (n - m); ++i)
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{
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m_nState[i] = m_nState[i + m] ^ twiddle(m_nState[i], m_nState[i + 1]);
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}
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for (int i = n - m; i < (n - 1); ++i)
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{
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m_nState[i] = m_nState[i + m - n] ^ twiddle(m_nState[i], m_nState[i + 1]);
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}
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m_nState[n - 1] = m_nState[m - 1] ^ twiddle(m_nState[n - 1], m_nState[0]);
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p = 0; // reset position
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}
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void CMTRand_int32::seed(uint32 s) // init by 32 bit seed
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{ //if (s == 0)
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//m_nRandom = 1;
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for (int i = 0; i < n; ++i)
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{
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m_nState[i] = 0x0UL;
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}
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m_nState[0] = s;
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for (int i = 1; i < n; ++i)
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{
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m_nState[i] = 1812433253UL * (m_nState[i - 1] ^ (m_nState[i - 1] >> 30)) + i;
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// see Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier
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// in the previous versions, MSBs of the seed affect only MSBs of the array m_nState
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// 2002/01/09 modified by Makoto Matsumoto
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}
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p = n; // force gen_state() to be called for next random number
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}
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void CMTRand_int32::seed(const uint32* array, int size) // init by array
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{
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seed(19650218UL);
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int i = 1, j = 0;
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for (int k = ((n > size) ? n : size); k; --k)
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{
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m_nState[i] = (m_nState[i] ^ ((m_nState[i - 1] ^ (m_nState[i - 1] >> 30)) * 1664525UL))
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+ array[j] + j; // non linear
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++j;
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j %= size;
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if ((++i) == n)
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{
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m_nState[0] = m_nState[n - 1];
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i = 1;
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}
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}
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for (int k = n - 1; k; --k)
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{
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PREFAST_SUPPRESS_WARNING(6385) PREFAST_SUPPRESS_WARNING(6386) m_nState[i] = (m_nState[i] ^ ((m_nState[i - 1] ^ (m_nState[i - 1] >> 30)) * 1566083941UL)) - i;
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if ((++i) == n)
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{
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m_nState[0] = m_nState[n - 1];
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i = 1;
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}
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}
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m_nState[0] = 0x80000000UL; // MSB is 1; assuring non-zero initial array
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p = n; // force gen_state() to be called for next random number
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}
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