52 lines
1.0 KiB
C
52 lines
1.0 KiB
C
#include <stdint.h>
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#include <stddef.h>
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#include "uniqid.h"
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#include "atomic.h"
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#include "spinlock/spinlock.h"
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static const char *base62 = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
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static uint32_t uniqstate = 0u;
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SpinLock uniqstate_spinlock;
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void randcrypto_uniqid_init(void) {
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spinlock_init(&uniqstate_spinlock);
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}
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uint32_t uniqmix32(uint32_t x) {
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x ^= x >> 16;
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x *= 0x85ebca6bU;
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x ^= x >> 13;
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x *= 0xc2b2ae35U;
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x ^= x >> 16;
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return x;
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}
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void randcrypto_gen_uniqid(char *out, size_t n) {
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if (!out || n == 0) {
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return;
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}
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spinlock_acquire(&uniqstate_spinlock);
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if (uniqstate == 0u) {
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uintptr_t p = (uintptr_t)(void *)&uniqstate;
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uint32_t seed = (uint32_t)(p ^ (p >> 16));
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uniqstate = seed ^ 0x9E3779B9u;
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if (uniqstate == 0u) {
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uniqstate = 1u;
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}
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}
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uniqstate += 0x9E3779B1u;
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uint32_t v = uniqmix32(uniqstate);
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spinlock_release(&uniqstate_spinlock);
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for (size_t i = 0; i < n; i++) {
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v = uniqmix32(v + i * 0x27d4eb2dU);
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out[i] = base62[v % 62u];
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}
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out[n] = '\0';
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}
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