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49 lines (45 loc) · 2.02 KB
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// mtrand.cpp, see include file mtrand.h for information
#include "mtrand.h"
// non-inline function definitions and static member definitions cannot
// reside in header file because of the risk of multiple declarations
// initialization of static private members
unsigned long MTRand_int32::state[n] = {0x0UL};
int MTRand_int32::p = 0;
bool MTRand_int32::init = false;
void MTRand_int32::gen_state() { // generate new state vector
for (int i = 0; i < (n - m); ++i)
state[i] = state[i + m] ^ twiddle(state[i], state[i + 1]);
for (int i = n - m; i < (n - 1); ++i)
state[i] = state[i + m - n] ^ twiddle(state[i], state[i + 1]);
state[n - 1] = state[m - 1] ^ twiddle(state[n - 1], state[0]);
p = 0; // reset position
}
void MTRand_int32::seed(unsigned long s) { // init by 32 bit seed
state[0] = s & 0xFFFFFFFFUL; // for > 32 bit machines
for (int i = 1; i < n; ++i) {
state[i] = 1812433253UL * (state[i - 1] ^ (state[i - 1] >> 30)) + i;
// see Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier
// in the previous versions, MSBs of the seed affect only MSBs of the array state
// 2002/01/09 modified by Makoto Matsumoto
state[i] &= 0xFFFFFFFFUL; // for > 32 bit machines
}
p = n; // force gen_state() to be called for next random number
}
void MTRand_int32::seed(const unsigned long* array, int size) { // init by array
seed(19650218UL);
int i = 1, j = 0;
for (int k = ((n > size) ? n : size); k; --k) {
state[i] = (state[i] ^ ((state[i - 1] ^ (state[i - 1] >> 30)) * 1664525UL))
+ array[j] + j; // non linear
state[i] &= 0xFFFFFFFFUL; // for > 32 bit machines
++j; j %= size;
if ((++i) == n) { state[0] = state[n - 1]; i = 1; }
}
for (int k = n - 1; k; --k) {
state[i] = (state[i] ^ ((state[i - 1] ^ (state[i - 1] >> 30)) * 1566083941UL)) - i;
state[i] &= 0xFFFFFFFFUL; // for > 32 bit machines
if ((++i) == n) { state[0] = state[n - 1]; i = 1; }
}
state[0] = 0x80000000UL; // MSB is 1; assuring non-zero initial array
p = n; // force gen_state() to be called for next random number
}