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#ifndef MESH_RAND_H__
#define MESH_RAND_H__

#include <stdint.h>

/**
 * @defgroup RAND Random number generator
 * @ingroup MESH_CORE
 * This module abstracts the HW RNG, as well as providing a simple PRNG for non-cryptographic
 * random numbers.
 * @{
 */

/** PRNG instance structure. */
typedef struct
{
    uint32_t a; /**< PRNG state variable A */
    uint32_t b; /**< PRNG state variable B */
    uint32_t c; /**< PRNG state variable C */
    uint32_t d; /**< PRNG state variable D */
} prng_t;

/**
 * Seed a PRNG-instance with random values from the HW RNG module.
 *
 * @note The prng-structure is not seeded by default, and all new instances should be seeded
 *       before use. The probability of cycles shorter than 2^64 are assumed neglectable, but
 *       it is still advisable to reseed the prng with regular intervals.
 *
 * @param[in,out] p_prng A pointer to a prng_t structure to be seeded.
 */
void rand_prng_seed(prng_t* p_prng);

/**
 * Get a 32bit pseudo-random value from the given PRNG instance.
 *
 * @warning The PRNG must NEVER be used for cryptographic purposes, as it is considered unsafe.
 *
 * @param[in,out] p_prng The PRNG instance to get a value from. The instance is altered for each
 *                get.
 *
 * @return A 32bit pseudo-random value.
 */
uint32_t rand_prng_get(prng_t* p_prng);

/**
 * Get a variable length array of random bytes from the HW RNG module.
 *
 * @param[out] p_result An array to copy the random values to. Must be at least of length len.
 * @param[in] len The number of bytes to be copied into the p_result parameter.
 */
void rand_hw_rng_get(uint8_t* p_result, uint16_t len);

/** @} */

#endif /* RAND_H__ */
