lora-irrigation/strobe_rng_init.c

#include <strobe.h>

#include <strobe_rng_init.h>

/*
 * Note: rng_save is really REAL_RNG_SAVE_LEN, BUT, we want to use the
 * uninitalized SRAM after it as entropy.
 */
extern uint8_t rng_save[2*1048];
extern int rng_save_len;

#define REAL_RNG_SAVE_LEN       ((int)&rng_save_len)

void
strobe_rng_init(void)
{
	int r;

	/*
	 * Seed RNG
	 * On first boot, SRAM is uninitialized and randomness from
	 * it is used.  On reset, the previously saved state is used.
	 */
	strobe_seed_prng(rng_save, 2*1024);

	/*
	 * Save entropy for next reset.
	 */
	r = strobe_randomize(rng_save, REAL_RNG_SAVE_LEN);
	(void)r;
}