Random

Pseudo Random Number Generator (PRNG) More...

Detailed Description

Pseudo Random Number Generator (PRNG)

Various implementations of a PRNG are available:

• Tiny Mersenne Twister (default)
• Mersenne Twister
• Simple Park-Miller PRNG
• Musl C PRNG
• Fortuna (CS)PRNG
• Hardware Random Number Generator (non-seedable) HWRNG differ in how they generate random numbers and may not use a PRNG internally. Refer to the manual of your MCU for details.

By default, the auto_init_random module is enabled, which initializes the PRNG on startup. However, there is no lower limit on the entropy provided at that time. Unless the periph_hwrng module is used, entropy may be as little as zero (the constant may even be the same across devices).

Modules
	SHAX random number generator
	SHA based random number generator implementation(CSPRNG).

Files
file	random.h
	Common interface to the software PRNG.

Macros
#define	RANDOM_SEED_DEFAULT   (1)
	Seed selected when all tries to collect seeds from a random source failed.
#define	PRNG_FLOAT   (0)
	Enables support for floating point random number generation.

Functions
void	random_init (uint32_t s)
	initializes PRNG with a seed
void	random_init_by_array (uint32_t init_key[], int key_length)
	initialize by an array with array-length init_key is the array for initializing keys key_length is its length slight change for C++, 2004/2/26
uint32_t	random_uint32 (void)
	generates a random number on [0,0xffffffff]-interval
void	random_bytes (void *buf, size_t size)
	writes random bytes in the [0,0xff]-interval to memory
uint32_t	random_uint32_range (uint32_t a, uint32_t b)
	generates a random number r with a <= r < b.
double	random_real (void)
	generates a random number on [0,1)-real-interval
double	random_real_inclusive (void)
	generates a random number on [0,1]-real-interval
double	random_real_exclusive (void)
	generates a random number on (0,1)-real-interval
double	random_res53 (void)
	generates a random number on [0,1) with 53-bit resolution

Macro Definition Documentation

PRNG_FLOAT

#define PRNG_FLOAT   (0)

Enables support for floating point random number generation.

Definition at line 57 of file random.h.

RANDOM_SEED_DEFAULT

#define RANDOM_SEED_DEFAULT   (1)

Seed selected when all tries to collect seeds from a random source failed.

Definition at line 50 of file random.h.

Function Documentation

random_init()

void random_init

(

uint32_t

s

)

initializes PRNG with a seed

Users only need to call this if the auto_init_random module is disabled, or provides insufficient quality entropy.

Warning

Currently, the random module uses a global state => multiple calls to random_init will reset the existing state of the PRNG.

Parameters

s	seed for the PRNG

random_init_by_array()

void random_init_by_array	(	uint32_t	init_key[],
		int	key_length
	)

initialize by an array with array-length init_key is the array for initializing keys key_length is its length slight change for C++, 2004/2/26

Parameters

init_key	array of keys (seeds) to initialize the PRNG
key_length	number of elements in init_key

random_real()

double random_real

(

void

)

generates a random number on [0,1)-real-interval

Returns

a random number on [0,1)-real-interval

random_real_exclusive()

double random_real_exclusive

(

void

)

generates a random number on (0,1)-real-interval

Returns

a random number on (0,1)-real-interval

random_real_inclusive()

double random_real_inclusive

(

void

)

generates a random number on [0,1]-real-interval

Returns

a random number on [0,1]-real-interval

random_res53()

double random_res53

(

void

)

generates a random number on [0,1) with 53-bit resolution

Returns

a random number on [0,1) with 53-bit resolution

random_uint32()

uint32_t random_uint32

(

void

)

generates a random number on [0,0xffffffff]-interval

Returns

a random number on [0,0xffffffff]-interval

random_uint32_range()

uint32_t random_uint32_range	(	uint32_t	a,
		uint32_t	b
	)

generates a random number r with a <= r < b.

Parameters

[in]	a	minimum for random number
[in]	b	upper bound for random number

Precondition

a < b

Returns

a random number on [a,b)-interval