kopia lustrzana https://github.com/OpenRTX/OpenRTX
77 wiersze
2.6 KiB
C
77 wiersze
2.6 KiB
C
/***************************************************************************
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* Copyright (C) 2023 - 2025 by Federico Amedeo Izzo IU2NUO, *
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* Niccolò Izzo IU2KIN *
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* Frederik Saraci IU2NRO *
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* Silvano Seva IU2KWO *
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 3 of the License, or *
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* (at your option) any later version. *
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* *
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* This program is distributed in the hope that it will be useful, *
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* but WITHOUT ANY WARRANTY; without even the implied warranty of *
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
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* GNU General Public License for more details. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program; if not, see <http://www.gnu.org/licenses/> *
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***************************************************************************/
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#include <interfaces/delays.h>
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#include <peripherals/rng.h>
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#include <stm32f4xx.h>
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#include <pthread.h>
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static uint32_t oldValue = 0;
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void rng_init()
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{
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RCC->AHB2ENR |= RCC_AHB2ENR_RNGEN;
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__DSB();
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}
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void rng_terminate()
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{
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RCC->AHB2ENR &= ~RCC_AHB2ENR_RNGEN;
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__DSB();
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}
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uint32_t rng_get()
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{
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uint32_t value;
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RNG->CR = RNG_CR_RNGEN;
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/*
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* The datasheet says that the RNG takes 40 clock cycles of the 48MHz
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* clock to generate a number, that is around 0.83us. It has not much
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* sense to put a delay here, we can just spin a bit and wait.
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*/
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while(1)
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{
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uint32_t status = RNG->SR;
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// Got a new number, return it only if different from the previous one
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if((status & RNG_SR_DRDY) != 0)
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{
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value = RNG->DR;
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if(value != oldValue)
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break;
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}
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// Error, "power cycle" the RNG and retry
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if((status & (RNG_SR_SECS | RNG_SR_CECS)) != 0)
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{
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RNG->CR = 0;
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delayUs(1);
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RNG->CR = RNG_CR_RNGEN;
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}
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}
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RNG->CR = 0;
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oldValue = value;
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return value;
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}
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