mirror of
https://github.com/zephyrproject-rtos/zephyr
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6216c6cf5b
Create syscalls to make possible using random APIs from user mode threads. These APIs can have different implementations, like using entropy driver or Xoroshiro128. Some of these implementations also have some globals to preserve state between calls. Make it run entire in user space would require user adding these globals to their memeory domains and/or grant access to entropy device. Syscalls simplify its usage. Signed-off-by: Flavio Ceolin <flavio.ceolin@intel.com>
82 lines
1.8 KiB
C
82 lines
1.8 KiB
C
/*
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* Copyright (c) 2013-2015 Wind River Systems, Inc.
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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/**
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* @file
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* @brief Non-random number generator based on system timer
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*
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* This module provides a non-random implementation of sys_rand32_get(), which
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* is not meant to be used in a final product as a truly random number
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* generator. It was provided to allow testing on a platform that does not (yet)
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* provide a random number generator.
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*/
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#include <random/rand32.h>
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#include <drivers/timer/system_timer.h>
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#include <kernel.h>
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#include <sys/atomic.h>
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#include <string.h>
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#if defined(__GNUC__)
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/*
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* Symbols used to ensure a rapid series of calls to random number generator
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* return different values.
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*/
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static atomic_val_t _rand32_counter;
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#define _RAND32_INC 1000000013
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/**
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*
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* @brief Get a 32 bit random number
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*
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* The non-random number generator returns values that are based off the
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* target's clock counter, which means that successive calls will return
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* different values.
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*
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* @return a 32-bit number
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*/
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uint32_t z_impl_sys_rand32_get(void)
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{
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return k_cycle_get_32() + atomic_add(&_rand32_counter, _RAND32_INC);
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}
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/**
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*
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* @brief Fill destination buffer with random numbers
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*
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* The non-random number generator returns values that are based off the
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* target's clock counter, which means that successive calls will return
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* different values.
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*
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* @param dst destination buffer to fill
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* @param outlen size of destination buffer to fill
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*
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* @return N/A
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*/
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void z_impl_sys_rand_get(void *dst, size_t outlen)
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{
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uint32_t len = 0;
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uint32_t blocksize = 4;
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uint32_t ret;
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uint32_t *udst = (uint32_t *)dst;
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while (len < outlen) {
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ret = sys_rand32_get();
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if ((outlen-len) < sizeof(ret)) {
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blocksize = len;
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(void)memcpy(udst, &ret, blocksize);
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} else {
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(*udst++) = ret;
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}
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len += blocksize;
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}
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}
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#endif /* __GNUC__ */
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