64 lines
1.3 KiB
C
64 lines
1.3 KiB
C
#include <stdint.h>
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#include <stddef.h>
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#include "randcrypto/uniqid.h"
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#include "randcrypto/physrand.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 uniqseed(void) {
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if (uniqstate != 0u)
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return;
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uint32_t seed = 0;
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int32_t r = randcrypto_get_physrand();
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if (r != -1) {
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seed = (uint32_t)r;
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} else {
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uintptr_t p = (uintptr_t)(void *)&uniqstate;
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seed = (uint32_t)(p ^ (p>>32)) ^ 0x9E3779B9u;
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}
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uniqstate = seed ? seed : 1u;
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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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uniqseed();
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int32_t r = randcrypto_get_physrand();
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uint32_t extra = (r != -1) ? (uint32_t)r : uniqstate * 0x27d4eb2dU;
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uniqstate += 0x9E3779B1u;
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uint32_t v = uniqmix32(uniqstate ^ extra);
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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 * 0x85ebca6bU);
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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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