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52 lines
1.2 KiB
C++
52 lines
1.2 KiB
C++
#include <stdlib.h>
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#include "WuRng.h"
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static const char kCharacterTable[] =
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"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
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static inline uint64_t rotl(const uint64_t x, int k) {
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return (x << k) | (x >> (64 - k));
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}
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static uint64_t WuGetRngSeed() {
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uint64_t x = rand();
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uint64_t z = (x += UINT64_C(0x9E3779B97F4A7C15));
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z = (z ^ (z >> 30)) * UINT64_C(0xBF58476D1CE4E5B9);
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z = (z ^ (z >> 27)) * UINT64_C(0x94D049BB133111EB);
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return z ^ (z >> 31);
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}
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static void WuRngInit(WuRngState* state, uint64_t seed) {
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state->s[0] = seed;
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state->s[1] = seed;
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}
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static uint64_t WuRngNext(WuRngState* state) {
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const uint64_t s0 = state->s[0];
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uint64_t s1 = state->s[1];
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const uint64_t result = s0 + s1;
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s1 ^= s0;
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state->s[0] = rotl(s0, 55) ^ s1 ^ (s1 << 14);
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state->s[1] = rotl(s1, 36);
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return result;
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}
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void WuRandomString(char* out, size_t length) {
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WuRngState state;
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WuRngInit(&state, WuGetRngSeed());
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for (size_t i = 0; i < length; i++) {
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out[i] = kCharacterTable[WuRngNext(&state) % (sizeof(kCharacterTable) - 1)];
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}
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}
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uint64_t WuRandomU64() {
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WuRngState state;
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WuRngInit(&state, WuGetRngSeed());
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return WuRngNext(&state);
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}
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uint32_t WuRandomU32() { return (uint32_t)WuRandomU64(); }
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