Nils O. Selåsdal
77 lines
1.2 KiB
C
77 lines
1.2 KiB
C
/*Copyright (c) 2004 Nils O. Selåsdal <NOS {on} Utel {dot} no> */
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/*Straight forward attempt at a Mersenne Twister PRNG */
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#include "ucore/mersenne_twister.h"
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/*Beware , pollution. But the names are from the spec */
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enum {
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N = MT_RAND_N,
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w = 32,
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M = 387,
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R = 19,
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U = 0x80000000,
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LL= 0x7FFFFFFF,
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a = 0x9908B0DF,
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s = 7,
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t = 15,
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b = 0x9D2C5680,
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c = 0xEFC60000,
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l = 18,
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u = 11,
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};
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void mtsrand(int seed, MTRand *r)
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{
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int j;
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for (j = 0 ; j < N ; j++) {
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r->x[j] = seed * ((j+1)<< 3)|0x1;
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}
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r->i = 0;
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}
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unsigned int mtrand(MTRand *r)
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{
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unsigned int y;
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unsigned int ch[] = {0, a};
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y = r->x[r->i] & U;
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y |= r->x[r->i % N];
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y &= LL;
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r->x[r->i] = r->x[(r->i + M ) %N];
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r->x[r->i] ^= y >> 1;
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r->x[r->i] ^= ch[y&0x1];
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y = r->x[r->i];
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y ^= y >> u;
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y ^= (y << s) & b;
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y ^= (y << t) & c;
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y ^= y >> l;
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r->i = (r->i + 1) % N;
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return y;
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}
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#ifdef TEST_MT
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#include <stdio.h>
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#include <time.h>
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int main(int argc,char *argv[])
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{
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MTRand r;
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mtsrand(time(NULL),&r);
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for (;;){
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unsigned int _y = mtrand(&r);
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if (_y < 100)
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printf("%u \n",_y);
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}
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return 0;
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}
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#endif
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