/** @addtogroup rng_file * * This library supports the random number generator peripheral (RNG) in the * STM32F4 series of ARM Cortex Microcontrollers by ST Microelectronics. * * 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 . */ #include /**@{*/ /** 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 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; } /**@}*/