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143 lines
3.5 KiB
C
143 lines
3.5 KiB
C
/*
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* Copyright (C) 2013 Freie Universität Berlin
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @defgroup sys_random Random
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* @ingroup sys
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* @brief Pseudo Random Number Generator (PRNG)
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*
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* Various implementations of a PRNG are available:
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* - Tiny Mersenne Twister (default)
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* - Mersenne Twister
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* - Simple Park-Miller PRNG
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* - Musl C PRNG
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* - Fortuna (CS)PRNG
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* - Hardware Random Number Generator (non-seedable)
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* HWRNG differ in how they generate random numbers and may not use a PRNG internally.
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* Refer to the manual of your MCU for details.
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*
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* By default, the `auto_init_random` module is enabled, which initializes the
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* PRNG on startup. However, there is no lower limit on the entropy provided at
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* that time. Unless the `periph_hwrng` module is used, entropy may be as
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* little as zero (the constant may even be the same across devices).
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*
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* @{
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*
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* @file
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* @brief Common interface to the software PRNG
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*/
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#ifndef RANDOM_H
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#define RANDOM_H
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#include <inttypes.h>
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#include <stddef.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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#ifndef RANDOM_SEED_DEFAULT
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/**
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* @brief Seed selected when all tries to collect seeds from a random source
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* failed
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*/
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#define RANDOM_SEED_DEFAULT (1)
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#endif
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/**
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* @brief Enables support for floating point random number generation
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*/
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#ifndef PRNG_FLOAT
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# define PRNG_FLOAT (0)
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#endif
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/**
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* @brief initializes PRNG with a seed
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*
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* Users only need to call this if the `auto_init_random` module is disabled,
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* or provides insufficient quality entropy.
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*
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* @warning Currently, the random module uses a global state
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* => multiple calls to @ref random_init will reset the existing
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* state of the PRNG.
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*
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* @param s seed for the PRNG
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*/
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void random_init(uint32_t s);
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/**
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* @brief initialize by an array with array-length
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* init_key is the array for initializing keys
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* key_length is its length
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* slight change for C++, 2004/2/26
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*
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* @param init_key array of keys (seeds) to initialize the PRNG
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* @param key_length number of elements in init_key
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*/
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void random_init_by_array(uint32_t init_key[], int key_length);
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/**
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* @brief generates a random number on [0,0xffffffff]-interval
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* @return a random number on [0,0xffffffff]-interval
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*/
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uint32_t random_uint32(void);
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/**
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* @brief writes random bytes in the [0,0xff]-interval to memory
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*/
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void random_bytes(void *buf, size_t size);
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/**
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* @brief generates a random number r with a <= r < b.
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*
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* @param[in] a minimum for random number
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* @param[in] b upper bound for random number
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*
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* @pre a < b
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*
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* @return a random number on [a,b)-interval
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*/
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uint32_t random_uint32_range(uint32_t a, uint32_t b);
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#if PRNG_FLOAT || defined(DOXYGEN)
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/* These real versions are due to Isaku Wada, 2002/01/09 added */
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/**
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* @brief generates a random number on [0,1)-real-interval
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* @return a random number on [0,1)-real-interval
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*/
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double random_real(void);
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/**
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* @brief generates a random number on [0,1]-real-interval
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* @return a random number on [0,1]-real-interval
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*/
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double random_real_inclusive(void);
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/**
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* @brief generates a random number on (0,1)-real-interval
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* @return a random number on (0,1)-real-interval
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*/
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double random_real_exclusive(void);
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/**
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* @brief generates a random number on [0,1) with 53-bit resolution
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* @return a random number on [0,1) with 53-bit resolution
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*/
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double random_res53(void);
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#endif /* PRNG_FLOAT */
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#ifdef __cplusplus
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}
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#endif
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#endif /* RANDOM_H */
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/** @} */
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