trezor-firmware/speed-stm32/rand.c

#include <libopencm3/stm32/f2/rng.h>
#include "rand.h"

void init_rand(void) {
	RNG_CR |= RNG_CR_IE | RNG_CR_RNGEN;
}

uint32_t random32(void) {
	static uint32_t last = 0, new = 0;
	while (new == last) {
		if (((RNG_SR & (RNG_SR_SEIS | RNG_SR_CEIS)) == 0) && ((RNG_SR & RNG_SR_DRDY) > 0)) {
			new = RNG_DR;
		}
	}
	last = new;
	return new;
}