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random.c
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random.c
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/*
* Copyright (c) 2020, Toshiba BRIL
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*---------------------------------------------------------------------------*/
/**
* \addtogroup nrf52840
* @{
*
* \addtogroup nrf52840-dev Device drivers
* @{
*
* \addtogroup nrf52840-rng Hardware random number generator
* @{
*
* \file
* Wrapper around rand() using the hardware RNG for seeding.
*
* This file overrides os/lib/random.c.
*/
/*---------------------------------------------------------------------------*/
#include <stdlib.h>
#include <nrfx_rng.h>
/*---------------------------------------------------------------------------*/
unsigned short
random_rand(void)
{
return (unsigned short)rand();
}
/*---------------------------------------------------------------------------*/
/**
* \brief Initialize the libc random number generator from the hardware RNG.
* \param seed Ignored.
*
*/
void
random_init(unsigned short seed)
{
(void)seed;
unsigned short hwrng = 0;
NRF_RNG->TASKS_START = 1;
NRF_RNG->EVENTS_VALRDY = 0;
while(!NRF_RNG->EVENTS_VALRDY);
hwrng = (NRF_RNG->VALUE & 0xFF);
NRF_RNG->EVENTS_VALRDY = 0;
while(!NRF_RNG->EVENTS_VALRDY);
hwrng |= ((NRF_RNG->VALUE & 0xFF) << 8);
NRF_RNG->TASKS_STOP = 1;
srand(hwrng);
}
/*---------------------------------------------------------------------------*/
/**
* @}
* @}
* @}
*/