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/**
* @file random.c
* Provides true random number generation functionality
*
* Copyright (C) 2018 Clyne Sullivan
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include <random.h>
#include <stm32l476xx.h>
#include <clock.h>
void random_init(void)
{
// setup and enable RNG clock
RCC->CCIPR &= ~(RCC_CCIPR_CLK48SEL);
RCC->CCIPR |= RCC_CCIPR_CLK48SEL_1;
RCC->AHB2ENR |= RCC_AHB2ENR_RNGEN;
RNG->CR |= RNG_CR_RNGEN;
}
uint32_t random_get(void)
{
if (RNG->SR & (RNG_SR_SEIS | RNG_SR_CEIS))
return 0;
while (!(RNG->SR & RNG_SR_DRDY))
delay(1);
return RNG->DR;
}
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