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random: Use unmodified SFC64.

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Nicholas J. Kain 2023-06-24 01:05:09 -04:00
parent 98e0ca3f6f
commit 219443ba7a
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1 changed files with 2 additions and 5 deletions
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nk/random.c
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@ -1,11 +1,9 @@
// Copyright 2013-2022 Nicholas J. Kain <njkain at gmail dot com> // Copyright 2013-2023 Nicholas J. Kain <njkain at gmail dot com>
// SPDX-License-Identifier: MIT // SPDX-License-Identifier: MIT
#include <stdint.h> #include <stdint.h>
#include "nk/hwrng.h" #include "nk/hwrng.h"
#include "nk/random.h" #include "nk/random.h"
// SFC64 modified to use a Weyl counter.
void nk_random_init(struct nk_random_state *s) void nk_random_init(struct nk_random_state *s)
{ {
nk_hwrng_bytes(s->seed, sizeof(uint64_t) * 3); nk_hwrng_bytes(s->seed, sizeof(uint64_t) * 3);
@ -19,8 +17,7 @@ static inline uint64_t rotl64(const uint64_t x, int k) {
uint64_t nk_random_u64(struct nk_random_state *s) uint64_t nk_random_u64(struct nk_random_state *s)
{ {
const uint64_t t = (s->seed[0] + s->seed[1]) ^ s->seed[3]; const uint64_t t = s->seed[0] + s->seed[1] + s->seed[3]++;
s->seed[3] += 0x6a09e667a7541669ull;
s->seed[0] = s->seed[1] ^ (s->seed[1] >> 11); s->seed[0] = s->seed[1] ^ (s->seed[1] >> 11);
s->seed[1] = s->seed[2] + (s->seed[2] << 3); s->seed[1] = s->seed[2] + (s->seed[2] << 3);
s->seed[2] = rotl64(s->seed[2], 24) + t; s->seed[2] = rotl64(s->seed[2], 24) + t;