hwrng.c
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/*
* Copyright (C) 2014-2016 Freie Universität Berlin
* 2015 Jan Wagner <mail@jwagner.eu>
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup cpu_nrf5x_common
* @{
*
* @file
* @brief Implementation of the hardware random number generator interface
*
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
* @author Frank Holtz <frank-riot2015@holtznet.de>
* @author Jan Wagner <mail@jwagner.eu>
*
* @}
*/
#include "cpu.h"
#include "periph/hwrng.h"
void hwrng_init(void)
{
/* nothing to do here */
}
void hwrng_read(uint8_t *buf, unsigned int num)
{
unsigned int count = 0;
/* power on RNG */
#ifdef CPU_FAM_NRF51
NRF_RNG->POWER = 1;
#endif
NRF_RNG->TASKS_START = 1;
/* read the actual random data */
while (count < num) {
/* sleep until number is generated */
while (NRF_RNG->EVENTS_VALRDY == 0) {
cpu_sleep_until_event();
}
buf[count++] = (uint8_t)NRF_RNG->VALUE;
/* NRF51 PAN #21 -> read value before clearing VALRDY */
NRF_RNG->EVENTS_VALRDY = 0;
}
/* power off RNG */
NRF_RNG->TASKS_STOP = 1;
#ifdef CPU_FAM_NRF51
NRF_RNG->POWER = 0;
#endif
}