101 lines
3.2 KiB
C
101 lines
3.2 KiB
C
/*
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* This file is part of the MicroPython project, http://micropython.org/
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*
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* The MIT License (MIT)
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*
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* Copyright (c) 2013-2018 Damien P. George
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "rtc.h"
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#include "rng.h"
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#if MICROPY_HW_ENABLE_RNG
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#define RNG_TIMEOUT_MS (10)
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uint32_t rng_get(void) {
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// Enable the RNG peripheral if it's not already enabled
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if (!(RNG->CR & RNG_CR_RNGEN)) {
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#if defined(STM32H7)
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// Set RNG Clock source
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__HAL_RCC_PLLCLKOUT_ENABLE(RCC_PLL1_DIVQ);
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__HAL_RCC_RNG_CONFIG(RCC_RNGCLKSOURCE_PLL);
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#endif
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__HAL_RCC_RNG_CLK_ENABLE();
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RNG->CR |= RNG_CR_RNGEN;
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}
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// Wait for a new random number to be ready, takes on the order of 10us
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uint32_t start = HAL_GetTick();
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while (!(RNG->SR & RNG_SR_DRDY)) {
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if (HAL_GetTick() - start >= RNG_TIMEOUT_MS) {
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return 0;
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}
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}
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// Get and return the new random number
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return RNG->DR;
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}
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// Return a 30-bit hardware generated random number.
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STATIC mp_obj_t pyb_rng_get(void) {
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return mp_obj_new_int(rng_get() >> 2);
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}
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MP_DEFINE_CONST_FUN_OBJ_0(pyb_rng_get_obj, pyb_rng_get);
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#else // MICROPY_HW_ENABLE_RNG
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// For MCUs that don't have an RNG we still need to provide a rng_get() function,
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// eg for lwIP and random.seed(). A pseudo-RNG is not really ideal but we go with
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// it for now, seeding with numbers which will be somewhat different each time. We
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// don't want to use urandom's pRNG because then the user won't see a reproducible
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// random stream.
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// Yasmarang random number generator by Ilya Levin
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// http://www.literatecode.com/yasmarang
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STATIC uint32_t pyb_rng_yasmarang(void) {
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static bool seeded = false;
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static uint32_t pad = 0, n = 0, d = 0;
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static uint8_t dat = 0;
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if (!seeded) {
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seeded = true;
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rtc_init_finalise();
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pad = *(uint32_t *)MP_HAL_UNIQUE_ID_ADDRESS ^ SysTick->VAL;
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n = RTC->TR;
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d = RTC->SSR;
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}
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pad += dat + d * n;
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pad = (pad << 3) + (pad >> 29);
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n = pad | 2;
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d ^= (pad << 31) + (pad >> 1);
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dat ^= (char)pad ^ (d >> 8) ^ 1;
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return pad ^ (d << 5) ^ (pad >> 18) ^ (dat << 1);
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}
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uint32_t rng_get(void) {
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return pyb_rng_yasmarang();
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}
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#endif // MICROPY_HW_ENABLE_RNG
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