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