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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2013-2018 Damien P. George
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "rng.h"
#if MICROPY_HW_ENABLE_RNG
#define RNG_TIMEOUT_MS (10)
uint32_t rng_get(void) {
// Enable the RNG peripheral if it's not already enabled
if (!(RNG->CR & RNG_CR_RNGEN)) {
__HAL_RCC_RNG_CLK_ENABLE();
RNG->CR |= RNG_CR_RNGEN;
}
// Wait for a new random number to be ready, takes on the order of 10us
uint32_t start = HAL_GetTick();
while (!(RNG->SR & RNG_SR_DRDY)) {
if (HAL_GetTick() - start >= RNG_TIMEOUT_MS) {
return 0;
}
}
// Get and return the new random number
return RNG->DR;
}
// Return a 30-bit hardware generated random number.
STATIC mp_obj_t pyb_rng_get(void) {
return mp_obj_new_int(rng_get() >> 2);
}
MP_DEFINE_CONST_FUN_OBJ_0(pyb_rng_get_obj, pyb_rng_get);
#endif // MICROPY_HW_ENABLE_RNG
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