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/** @addtogroup rng_file RNG peripheral API
* @ingroup peripheral_apis
*
* This library supports "version 1" of the random number generator
* peripheral (RNG) in the STM32 series of ARM Cortex Microcontrollers
* by ST Microelectronics. This is a common peripheral available on multiple
* devices in the family.
*
* LGPL License Terms @ref lgpl_license
*/
/*
* This file is part of the libopencm3 project.
*
* This library is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This library 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
#include <libopencm3/stm32/rng.h>
/**@{*/
/** Disable the Random Number Generator peripheral.
*/
void rng_disable(void)
{
RNG_CR &= ~RNG_CR_RNGEN;
}
/** Enable the Random Number Generator peripheral.
*/
void rng_enable(void)
{
RNG_CR |= RNG_CR_RNGEN;
}
/** Randomizes a number (non-blocking).
* Can fail if a clock error or seed error is detected. Consult the Reference
* Manual, but "try again", potentially after resetting the peripheral
* @param rand_nr pointer to a uint32_t that will be randomized.
* @returns true on success, pointer is only written to on success
* @sa rng_get_random_blocking
*/
bool rng_get_random(uint32_t *rand_nr)
{
/* data ready */
if (!(RNG_SR & RNG_SR_DRDY)) {
return false;
}
/* Check for errors */
if (RNG_SR & (RNG_SR_CECS | RNG_SR_SECS)) {
return false;
}
*rand_nr = RNG_DR;
return true;
}
/**
* Get a random number and block until it works.
* Unless you have a clock problem, this should always return "promptly"
* If you have a clock problem, you will wait here forever!
* @returns a random 32bit number
*/
uint32_t rng_get_random_blocking(void)
{
uint32_t rv;
bool done;
do {
if (RNG_SR & RNG_SR_SECS) {
rng_disable();
rng_enable();
}
done = rng_get_random(&rv);
} while (!done);
return rv;
}
/**@}*/
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