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#ifndef RBIMPL_INTERN_RANDOM_H /*-*-C++-*-vi:se ft=cpp:*/
#define RBIMPL_INTERN_RANDOM_H
/**
* @file
* @author Ruby developers <ruby-core@ruby-lang.org>
* @copyright This file is a part of the programming language Ruby.
* Permission is hereby granted, to either redistribute and/or
* modify this file, provided that the conditions mentioned in the
* file COPYING are met. Consult the file for details.
* @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are
* implementation details. Don't take them as canon. They could
* rapidly appear then vanish. The name (path) of this header file
* is also an implementation detail. Do not expect it to persist
* at the place it is now. Developers are free to move it anywhere
* anytime at will.
* @note To ruby-core: remember that this header can be possibly
* recursively included from extension libraries written in C++.
* Do not expect for instance `__VA_ARGS__` is always available.
* We assume C99 for ruby itself but we don't assume languages of
* extension libraries. They could be written in C++98.
* @brief MT19937 backended pseudo random number generator.
* @see Matsumoto, M., Nishimura, T., "Mersenne Twister: A 623-
* dimensionally equidistributed uniform pseudorandom number
* generator", ACM Trans. on Modeling and Computer Simulation, 8
* (1): pp 3-30, 1998. https://doi.org/10.1145/272991.272995
*/
#include "ruby/internal/dllexport.h"
#include "ruby/internal/value.h"
RBIMPL_SYMBOL_EXPORT_BEGIN()
/* random.c */
/**
* Generates a 32 bit random number.
*
* @return A random number.
* @note Now that we have ractors, the RNG behind this function is
* per-ractor.
*/
unsigned int rb_genrand_int32(void);
/**
* Generates a `double` random number.
*
* @return A random number.
* @note This function shares the RNG with rb_genrand_int32().
*/
double rb_genrand_real(void);
/**
* Resets the RNG behind rb_genrand_int32()/rb_genrand_real().
*
* @post The (now per-ractor) default RNG's internal state is cleared.
*/
void rb_reset_random_seed(void);
/**
* Generates a String of random bytes.
*
* @param[in,out] rnd An instance of ::rb_cRandom.
* @param[in] n Requested number of bytes.
* @return An instance of ::rb_cString, of binary, of `n` bytes length,
* whose contents are random bits.
*
* @internal
*
* @shyouhei doesn't know if this is an Easter egg or an official feature, but
* this function can take a wider range of objects, such as `Socket::Ifaddr`.
* The arguments are just silently ignored and the default RNG is used instead,
* if they are non-RNG.
*/
VALUE rb_random_bytes(VALUE rnd, long n);
/**
* Identical to rb_genrand_int32(), except it generates using the passed RNG.
*
* @param[in,out] rnd An instance of ::rb_cRandom.
* @return A random number.
*/
unsigned int rb_random_int32(VALUE rnd);
/**
* Identical to rb_genrand_real(), except it generates using the passed RNG.
*
* @param[in,out] rnd An instance of ::rb_cRandom.
* @return A random number.
*/
double rb_random_real(VALUE rnd);
/**
* Identical to rb_genrand_ulong_limited(), except it generates using the
* passed RNG.
*
* @param[in,out] rnd An instance of ::rb_cRandom.
* @param[in] limit Max possible return value.
* @return A random number, distributed in `[0, limit]` interval.
* @note Note it can return `limit`.
* @note Whether the return value distributes uniformly in the
* interval or not depends on how the argument RNG behaves; at
* least in case of MT19937 it does.
*/
unsigned long rb_random_ulong_limited(VALUE rnd, unsigned long limit);
/**
* Generates a random number whose upper limit is `i`.
*
* @param[in] i Max possible return value.
* @return A random number, uniformly distributed in `[0, limit]` interval.
* @note Note it can return `i`.
*/
unsigned long rb_genrand_ulong_limited(unsigned long i);
RBIMPL_SYMBOL_EXPORT_END()
#endif /* RBIMPL_INTERN_RANDOM_H */
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