121 lines
3.1 KiB
C
121 lines
3.1 KiB
C
/*
|
|
* Copyright (c) 2021, Commonwealth Scientific and Industrial Research
|
|
* Organisation (CSIRO) ABN 41 687 119 230.
|
|
*
|
|
* SPDX-License-Identifier: CC0-1.0
|
|
*
|
|
* Based on code written in 2019 by David Blackman and Sebastiano Vigna
|
|
* (vigna@acm.org)
|
|
*
|
|
* To the extent possible under law, the author has dedicated all copyright
|
|
* and related and neighboring rights to this software to the public domain
|
|
* worldwide. This software is distributed without any warranty.
|
|
*
|
|
* See <http://creativecommons.org/publicdomain/zero/1.0/>.
|
|
*
|
|
* From: https://prng.di.unimi.it/xoshiro128plusplus.c
|
|
*
|
|
* This is xoshiro128++ 1.0, one of our 32-bit all-purpose, rock-solid
|
|
* generators. It has excellent speed, a state size (128 bits) that is
|
|
* large enough for mild parallelism, and it passes all tests we are aware
|
|
* of.
|
|
*
|
|
* For generating just single-precision (i.e., 32-bit) floating-point
|
|
* numbers, xoshiro128+ is even faster.
|
|
*
|
|
* The state must be seeded so that it is not everywhere zero.
|
|
*/
|
|
|
|
#include <zephyr/init.h>
|
|
#include <zephyr/device.h>
|
|
#include <zephyr/drivers/entropy.h>
|
|
#include <zephyr/kernel.h>
|
|
#include <string.h>
|
|
|
|
static const struct device *const entropy_driver =
|
|
DEVICE_DT_GET(DT_CHOSEN(zephyr_entropy));
|
|
static uint32_t state[4];
|
|
static bool initialized;
|
|
|
|
static inline uint32_t rotl(const uint32_t x, int k)
|
|
{
|
|
return (x << k) | (x >> (32 - k));
|
|
}
|
|
|
|
static int xoshiro128_initialize(void)
|
|
{
|
|
if (!device_is_ready(entropy_driver)) {
|
|
return -ENODEV;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static void xoshiro128_init_state(void)
|
|
{
|
|
int rc;
|
|
|
|
/* This is not thread safe but it doesn't matter as we will just end
|
|
* up with a mix of random bytes from both threads.
|
|
*/
|
|
rc = entropy_get_entropy(entropy_driver, (uint8_t *)&state, sizeof(state));
|
|
if (rc == 0) {
|
|
initialized = true;
|
|
} else {
|
|
/* Entropy device failed or is not yet ready.
|
|
* Reseed the PRNG state with pseudo-random data until it can
|
|
* be properly seeded. This may be needed if random numbers are
|
|
* requested before the backing entropy device has been enabled.
|
|
*/
|
|
state[0] = k_cycle_get_32();
|
|
state[1] = k_cycle_get_32() ^ 0x9b64c2b0;
|
|
state[2] = k_cycle_get_32() ^ 0x86d3d2d4;
|
|
state[3] = k_cycle_get_32() ^ 0xa00ae278;
|
|
}
|
|
}
|
|
|
|
static uint32_t xoshiro128_next(void)
|
|
{
|
|
const uint32_t result = rotl(state[0] + state[3], 7) + state[0];
|
|
|
|
const uint32_t t = state[1] << 9;
|
|
|
|
state[2] ^= state[0];
|
|
state[3] ^= state[1];
|
|
state[1] ^= state[2];
|
|
state[0] ^= state[3];
|
|
|
|
state[2] ^= t;
|
|
|
|
state[3] = rotl(state[3], 11);
|
|
|
|
return result;
|
|
}
|
|
|
|
void z_impl_sys_rand_get(void *dst, size_t outlen)
|
|
{
|
|
size_t blocks = outlen / sizeof(uint32_t);
|
|
size_t rem = (outlen - (blocks * sizeof(uint32_t)));
|
|
uint32_t *unaligned = dst;
|
|
uint32_t ret;
|
|
|
|
if (unlikely(!initialized)) {
|
|
xoshiro128_init_state();
|
|
}
|
|
|
|
/* Write all full 32bit chunks */
|
|
while (blocks--) {
|
|
UNALIGNED_PUT(xoshiro128_next(), unaligned++);
|
|
}
|
|
/* Write trailing bytes */
|
|
if (rem) {
|
|
ret = xoshiro128_next();
|
|
memcpy(unaligned, &ret, rem);
|
|
}
|
|
}
|
|
|
|
/* In-tree entropy drivers will initialize in PRE_KERNEL_1; ensure that they're
|
|
* initialized properly before initializing ourselves.
|
|
*/
|
|
SYS_INIT(xoshiro128_initialize, PRE_KERNEL_2,
|
|
CONFIG_KERNEL_INIT_PRIORITY_DEFAULT);
|