52 lines
2.0 KiB
C++
52 lines
2.0 KiB
C++
// mtrand.cpp, see include file mtrand.h for information
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#include "mtrand.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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// initialization of static private members
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unsigned long MTRand_int32::state[n] = {0x0UL};
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int MTRand_int32::p = 0;
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bool MTRand_int32::init = false;
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void MTRand_int32::gen_state() { // generate new state vector
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for (int i = 0; i < (n - m); ++i)
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state[i] = state[i + m] ^ twiddle(state[i], state[i + 1]);
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for (int i = n - m; i < (n - 1); ++i)
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state[i] = state[i + m - n] ^ twiddle(state[i], state[i + 1]);
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state[n - 1] = state[m - 1] ^ twiddle(state[n - 1], state[0]);
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p = 0; // reset position
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}
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void MTRand_int32::seed(unsigned long s) { // init by 32 bit seed
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state[0] = s & 0xFFFFFFFFUL; // for > 32 bit machines
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for (int i = 1; i < n; ++i) {
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state[i] = 1812433253UL * (state[i - 1] ^ (state[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 state
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// 2002/01/09 modified by Makoto Matsumoto
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state[i] &= 0xFFFFFFFFUL; // for > 32 bit machines
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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 MTRand_int32::seed(const unsigned long* array, int size) { // init by array
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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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state[i] = (state[i] ^ ((state[i - 1] ^ (state[i - 1] >> 30)) * 1664525UL))
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+ array[j] + j; // non linear
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state[i] &= 0xFFFFFFFFUL; // for > 32 bit machines
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++j; j %= size;
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if ((++i) == n) { state[0] = state[n - 1]; i = 1; }
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}
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for (int k = n - 1; k; --k) {
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state[i] = (state[i] ^ ((state[i - 1] ^ (state[i - 1] >> 30)) * 1566083941UL)) - i;
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state[i] &= 0xFFFFFFFFUL; // for > 32 bit machines
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if ((++i) == n) { state[0] = state[n - 1]; i = 1; }
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}
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state[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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