60 lines
1.4 KiB
C
60 lines
1.4 KiB
C
#include <stdint.h>
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#include <stdio.h>
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#include <time.h>
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struct xorshift32_state {
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uint32_t a;
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};
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/* The state must be initialized to non-zero */
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uint32_t xorshift32(struct xorshift32_state *state) {
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/* Algorithm "xor" from p. 4 of Marsaglia, "Xorshift RNGs" */
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uint32_t x = state->a;
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x ^= x << 13;
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x ^= x >> 17;
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x ^= x << 5;
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return state->a = x;
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}
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struct xorshift64_state {
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uint64_t a;
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};
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/* The state must be initialized to non-zero */
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uint64_t xorshift64(struct xorshift64_state *state) {
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uint64_t x = state->a;
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x ^= x << 13;
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x ^= x >> 7;
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x ^= x << 17;
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return state->a = x;
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}
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/* struct xorshift128_state can alternatively be defined as a pair
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of uint64_t or a uint128_t where supported */
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struct xorshift128_state {
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uint32_t x[4];
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};
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/* The state must be initialized to non-zero */
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uint32_t xorshift128(struct xorshift128_state *state) {
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/* Algorithm "xor128" from p. 5 of Marsaglia, "Xorshift RNGs" */
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uint32_t t = state->x[3];
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uint32_t s = state->x[0]; /* Perform a contrived 32-bit shift. */
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state->x[3] = state->x[2];
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state->x[2] = state->x[1];
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state->x[1] = s;
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t ^= t << 11;
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t ^= t >> 8;
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return state->x[0] = t ^ s ^ (s >> 19);
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}
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int main(void) {
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struct xorshift32_state s = {};
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s.a = time(0);
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for (int a = 0; a < 10; a++) {
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printf("Number %d: %d\n", a, xorshift32(&s));
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}
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}
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