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/* Mersenne twister implementation from Michael Brundage. Public Domain.
MT is a very fast pseudo random number generator. This version works
on 32bit words. Changes by AK. */
#include <stdlib.h>
#include "mt.h"
int mt_index;
unsigned int mt_buffer[MT_LEN];
void mt_init(void)
{
int i;
srand(1);
for (i = 0; i < MT_LEN; i++)
mt_buffer[i] = rand();
mt_index = 0;
}
#define MT_IA 397
#define MT_IB (MT_LEN - MT_IA)
#define UPPER_MASK 0x80000000
#define LOWER_MASK 0x7FFFFFFF
#define MATRIX_A 0x9908B0DF
#define TWIST(b,i,j) ((b)[i] & UPPER_MASK) | ((b)[j] & LOWER_MASK)
#define MAGIC(s) (((s)&1)*MATRIX_A)
void mt_refill(void)
{
int i;
unsigned int s;
unsigned int * b = mt_buffer;
mt_index = 0;
i = 0;
for (; i < MT_IB; i++) {
s = TWIST(b, i, i+1);
b[i] = b[i + MT_IA] ^ (s >> 1) ^ MAGIC(s);
}
for (; i < MT_LEN-1; i++) {
s = TWIST(b, i, i+1);
b[i] = b[i - MT_IB] ^ (s >> 1) ^ MAGIC(s);
}
s = TWIST(b, MT_LEN-1, 0);
b[MT_LEN-1] = b[MT_IA-1] ^ (s >> 1) ^ MAGIC(s);
}
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