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67 lines
1.3 KiB
C
67 lines
1.3 KiB
C
/*
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* Copyright (C) 2014 Freie Universität Berlin
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*
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* This file is subject to the terms and conditions of the GNU Lesser General
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* Public License v2.1. See the file LICENSE in the top level directory for more
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* details.
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*/
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/**
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* @ingroup cpu_stm32f4
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* @{
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*
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* @file
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* @brief Low-level random number generator driver implementation
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*
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* @author Hauke Petersen <mail@haukepetersen.de>
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*
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* @}
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*/
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#include "cpu.h"
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#include "periph/random.h"
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#include "periph_conf.h"
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/* ignore file in case no RNG device is defined */
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#if RANDOM_NUMOF
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void random_init(void)
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{
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random_poweron();
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}
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int random_read(char *buf, unsigned int num)
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{
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/* cppcheck-suppress variableScope */
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uint32_t tmp;
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int count = 0;
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while (count < num) {
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/* wait for random data to be ready to read */
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while (!(RNG->SR & RNG_SR_DRDY));
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/* read next 4 bytes */
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tmp = RNG->DR;
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/* copy data into result vector */
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for (int i = 0; i < 4 && count < num; i++) {
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buf[count++] = (char)tmp;
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tmp = tmp >> 8;
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}
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}
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return count;
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}
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void random_poweron(void)
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{
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RCC->AHB2ENR |= RCC_AHB2ENR_RNGEN;
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RNG->CR = RNG_CR_RNGEN;
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}
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void random_poweroff(void)
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{
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RNG->CR = 0;
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RCC->AHB2ENR &= ~RCC_AHB2ENR_RNGEN;
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}
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#endif /* RANDOM_NUMOF */
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