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#include "mt19937-jump.h"
#include "mt19937.h"
/* 32-bits function */
/* return the i-th coefficient of the polynomial pf */
unsigned long get_coef(unsigned long *pf, unsigned int deg) {
if ((pf[deg >> 5] & (LSB << (deg & 0x1ful))) != 0)
return (1);
else
return (0);
}
void copy_state(mt19937_state *target_state, mt19937_state *state) {
int i;
for (i = 0; i < N; i++)
target_state->key[i] = state->key[i];
target_state->pos = state->pos;
}
/* next state generating function */
void gen_next(mt19937_state *state) {
int num;
unsigned long y;
static unsigned long mag02[2] = {0x0ul, MATRIX_A};
num = state->pos;
if (num < N - M) {
y = (state->key[num] & UPPER_MASK) | (state->key[num + 1] & LOWER_MASK);
state->key[num] = state->key[num + M] ^ (y >> 1) ^ mag02[y % 2];
state->pos++;
} else if (num < N - 1) {
y = (state->key[num] & UPPER_MASK) | (state->key[num + 1] & LOWER_MASK);
state->key[num] = state->key[num + (M - N)] ^ (y >> 1) ^ mag02[y % 2];
state->pos++;
} else if (num == N - 1) {
y = (state->key[N - 1] & UPPER_MASK) | (state->key[0] & LOWER_MASK);
state->key[N - 1] = state->key[M - 1] ^ (y >> 1) ^ mag02[y % 2];
state->pos = 0;
}
}
void add_state(mt19937_state *state1, mt19937_state *state2) {
int i, pt1 = state1->pos, pt2 = state2->pos;
if (pt2 - pt1 >= 0) {
for (i = 0; i < N - pt2; i++)
state1->key[i + pt1] ^= state2->key[i + pt2];
for (; i < N - pt1; i++)
state1->key[i + pt1] ^= state2->key[i + (pt2 - N)];
for (; i < N; i++)
state1->key[i + (pt1 - N)] ^= state2->key[i + (pt2 - N)];
} else {
for (i = 0; i < N - pt1; i++)
state1->key[i + pt1] ^= state2->key[i + pt2];
for (; i < N - pt2; i++)
state1->key[i + (pt1 - N)] ^= state2->key[i + pt2];
for (; i < N; i++)
state1->key[i + (pt1 - N)] ^= state2->key[i + (pt2 - N)];
}
}
/* compute pf(ss) using standard Horner method */
void horner1(unsigned long *pf, mt19937_state *state) {
int i = MEXP - 1;
mt19937_state *temp;
temp = (mt19937_state *)calloc(1, sizeof(mt19937_state));
while (get_coef(pf, i) == 0)
i--;
if (i > 0) {
copy_state(temp, state);
gen_next(temp);
i--;
for (; i > 0; i--) {
if (get_coef(pf, i) != 0)
add_state(temp, state);
else
;
gen_next(temp);
}
if (get_coef(pf, 0) != 0)
add_state(temp, state);
else
;
} else if (i == 0)
copy_state(temp, state);
else
;
copy_state(state, temp);
free(temp);
}
void mt19937_jump_state(mt19937_state *state) {
unsigned long *pf;
int i;
pf = (unsigned long *)calloc(P_SIZE, sizeof(unsigned long));
for (i = 0; i<P_SIZE; i++) {
pf[i] = poly_coef[i];
}
if (state->pos >= N) {
state->pos = 0;
}
horner1(pf, state);
free(pf);
}
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