blob: eaea324eeed9da8aa173cd66d0b23cf29ba439f9 [file] [log] [blame]
/*
* Copyright (c) 2013-2015 Wind River Systems, Inc.
*
* SPDX-License-Identifier: Apache-2.0
*/
/**
* @file
* @brief Non-random number generator based on system timer
*
* 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 <random/rand32.h>
#include <drivers/timer/system_timer.h>
#include <kernel.h>
#include <sys/atomic.h>
#include <string.h>
#if defined(__GNUC__)
/*
* Symbols used to ensure a rapid series of calls to random number generator
* return different values.
*/
static atomic_val_t _rand32_counter;
#define _RAND32_INC 1000000003U
/**
*
* @brief Get a 32 bit random number
*
* 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.
*
* @return a 32-bit number
*/
uint32_t z_impl_sys_rand32_get(void)
{
return k_cycle_get_32() + atomic_add(&_rand32_counter, _RAND32_INC);
}
/**
*
* @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 z_impl_sys_rand_get(void *dst, size_t outlen)
{
uint8_t *udst = dst;
uint32_t blocksize;
uint32_t ret;
while (outlen) {
ret = sys_rand32_get();
blocksize = MIN(outlen, sizeof(ret));
(void)memcpy((void *)udst, &ret, blocksize);
udst += blocksize;
outlen -= blocksize;
}
}
#endif /* __GNUC__ */