59 lines
1.4 KiB
C
59 lines
1.4 KiB
C
#include "prand.h"
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#include <stdint.h>
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#include <stdio.h>
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#include <time.h>
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#include <unistd.h>
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#define PRAND_BUILD_SEED \
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((uint64_t)(__TIME__[0]) * (uint64_t)(__TIME__[1]) * (uint64_t)(__TIME__[3]) * (uint64_t)(__TIME__[4]) * \
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(uint64_t)(__TIME__[6]) * (uint64_t)(__TIME__[7]))
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static uint64_t seed = PRAND_BUILD_SEED * 6364136223846793005ULL + 1;
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uint64_t prand() {
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seed = seed * 6364136223846793005ULL + 1;
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return seed;
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}
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inline uint64_t prand_range(uint64_t min, uint64_t max) {
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uint64_t range = max - min + 1;
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uint64_t x;
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uint64_t limit = UINT64_MAX - (UINT64_MAX % range);
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do {
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x = prand();
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} while (x > limit);
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return min + (x % range);
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}
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void sprand(uint64_t s) {
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if (s) {
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seed ^= (s * 0x9e3779b97f4a7c15ULL) + (seed << 6) + (seed >> 2);
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} else {
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seed ^= PRAND_BUILD_SEED;
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}
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}
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#undef PRAND_BUILD_SEED
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#define PRAND_MAIN
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#ifdef PRAND_MAIN
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int main() {
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// time(NULL) provides a somewhat unique seed at runtime
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sprand(time(NULL));
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sprand(getpid());
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sprand(0);
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uint64_t rn1 = prand();
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uint64_t rn2 = prand();
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printf("rn1 = %lu\n", rn1);
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printf("rn2 = %lu\n", rn2);
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for (int i = 0; i < 40; i++) {
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uint64_t random = prand_range(0, 1000);
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printf("random = %lu\n", random);
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}
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}
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#endif
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