diff options
Diffstat (limited to 'include/ruby/internal/intern/random.h')
| -rw-r--r-- | include/ruby/internal/intern/random.h | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/include/ruby/internal/intern/random.h b/include/ruby/internal/intern/random.h new file mode 100644 index 0000000000..5577f53cb4 --- /dev/null +++ b/include/ruby/internal/intern/random.h @@ -0,0 +1,116 @@ +#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 */ |