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/*
* Copyright (c) 2013-2014 Wind River Systems, Inc.
*
* SPDX-License-Identifier: Apache-2.0
*/
/**
* @file
* @brief Non-random number generator based on x86 CPU timestamp
*
* This module provides a non-random implementation of sys_rand32_get(), which
* is not meant to be used in a final product as a truly random number
* generator. It was provided to allow testing on a platform that does not (yet)
* provide a random number generator.
*/
#include <kernel.h>
#include <arch/cpu.h>
#include <random/rand32.h>
#include <string.h>
/**
*
* @brief Get a 32 bit random number
*
* The non-random number generator returns values that are based off the
* CPU's timestamp counter, which means that successive calls will normally
* display ever-increasing values.
*
* @return a 32-bit number
*/
u32_t sys_rand32_get(void)
{
return z_do_read_cpu_timestamp32();
}
/**
*
* @brief Fill destination buffer with random numbers
*
* The non-random number generator returns values that are based off the
* target's clock counter, which means that successive calls will return
* different values.
*
* @param dst destination buffer to fill
* @param outlen size of destination buffer to fill
*
* @return N/A
*/
void sys_rand_get(void *dst, size_t outlen)
{
u32_t len = 0;
u32_t blocksize = 4;
u32_t ret;
u32_t *udst = (u32_t *)dst;
while (len < outlen) {
ret = sys_rand32_get();
if ((outlen-len) < sizeof(ret)) {
blocksize = len;
(void)memcpy(udst, &ret, blocksize);
} else {
(*udst++) = ret;
}
len += blocksize;
}
}