diff --git a/include/ruby/internal/intern/random.h b/include/ruby/internal/intern/random.h index ced450fa0b..5577f53cb4 100644 --- a/include/ruby/internal/intern/random.h +++ b/include/ruby/internal/intern/random.h @@ -30,13 +30,85 @@ 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()