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Merge pull request #1611 from haukepetersen/add_stm32f4_random
cpu/stm32f4: added random number generator driver
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/* | ||
* Copyright (C) 2014 Freie Universität Berlin | ||
* | ||
* 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. | ||
*/ | ||
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/** | ||
* @ingroup cpu_stm32f4 | ||
* @{ | ||
* | ||
* @file | ||
* @brief Low-level random number generator driver implementation | ||
* | ||
* @author Hauke Petersen <mail@haukepetersen.de> | ||
* | ||
* @} | ||
*/ | ||
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#include "cpu.h" | ||
#include "periph/random.h" | ||
#include "periph_conf.h" | ||
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/* ignore file in case no RNG device is defined */ | ||
#if RANDOM_NUMOF | ||
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void random_init(void) | ||
{ | ||
random_poweron(); | ||
} | ||
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int random_read(char *buf, unsigned int num) | ||
{ | ||
uint32_t tmp; | ||
int count = 0; | ||
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while (count < num) { | ||
/* wait for random data to be ready to read */ | ||
while (!(RNG->SR & RNG_SR_DRDY)); | ||
/* read next 4 bytes */ | ||
tmp = RNG->DR; | ||
/* copy data into result vector */ | ||
for (int i = 0; i < 4 && count < num; i++) { | ||
buf[count++] = (char)tmp; | ||
tmp = tmp >> 8; | ||
} | ||
} | ||
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return count; | ||
} | ||
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void random_poweron(void) | ||
{ | ||
RCC->AHB2ENR |= RCC_AHB2ENR_RNGEN; | ||
RNG->CR = RNG_CR_RNGEN; | ||
} | ||
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void random_poweroff(void) | ||
{ | ||
RNG->CR = 0; | ||
RCC->AHB2ENR &= ~RCC_AHB2ENR_RNGEN; | ||
} | ||
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#endif /* RANDOM_NUMOF */ |