forked from Telodendria/Cytoplasm
Jordan Bancino
461357b526
This makes it easier to build Cytoplasm as a component of another program (for example, Telodendria), or as a standalone system library.
83 lines
3.2 KiB
C
83 lines
3.2 KiB
C
/*
|
|
* Copyright (C) 2022-2024 Jordan Bancino <@jordan:bancino.net>
|
|
*
|
|
* Permission is hereby granted, free of charge, to any person
|
|
* obtaining a copy of this software and associated documentation files
|
|
* (the "Software"), to deal in the Software without restriction,
|
|
* including without limitation the rights to use, copy, modify, merge,
|
|
* publish, distribute, sublicense, and/or sell copies of the Software,
|
|
* and to permit persons to whom the Software is furnished to do so,
|
|
* subject to the following conditions:
|
|
*
|
|
* The above copyright notice and this permission notice shall be
|
|
* included in all copies or portions of the Software.
|
|
*
|
|
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
|
|
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
|
|
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
|
|
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
|
|
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
|
|
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
|
|
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
|
|
* SOFTWARE.
|
|
*/
|
|
|
|
#ifndef CYTOPLASM_RAND_H
|
|
#define CYTOPLASM_RAND_H
|
|
|
|
/***
|
|
* @Nm Rand
|
|
* @Nd Thread-safe random numbers.
|
|
* @Dd February 16 2023
|
|
* @Xr Util
|
|
*
|
|
* .Nm
|
|
* is used for generating random numbers in a thread-safe way.
|
|
* Currently, one generator state is shared across all threads, which
|
|
* means that only one thread can generate random numbers at a time.
|
|
* This state is protected with a mutex to guarantee this behavior.
|
|
* In the future, a seed pool may be maintained to allow multiple
|
|
* threads to generate random numbers at the same time.
|
|
* .Pp
|
|
* The generator state is seeded on the first call to a function that
|
|
* needs it. The seed is determined by the current timestamp, the ID
|
|
* of the process, and the thread ID. These should all be sufficiently
|
|
* random sources, so the seed should be secure enough.
|
|
* .Pp
|
|
* .Nm
|
|
* currently uses a simple Mersenne Twister algorithm to generate
|
|
* random numbers. This algorithm was chosen because it is extremely
|
|
* popular and widespread. While it is likely not cryptographically
|
|
* secure, and does suffer some unfortunate pitfalls, this algorithm
|
|
* has stood the test of time and is simple enough to implement, so
|
|
* it was chosen over the alternatives.
|
|
* .Pp
|
|
* .Nm
|
|
* does not use any random number generator functions from the C
|
|
* standard library, since these are often flawed.
|
|
*/
|
|
|
|
#include <stddef.h>
|
|
#include <stdint.h>
|
|
|
|
/**
|
|
* Generate a single random 32-bit integer between 0 and the
|
|
* passed value.
|
|
*/
|
|
extern uint32_t RandInt(uint32_t);
|
|
|
|
/**
|
|
* Generate the number of integers specified by the second argument
|
|
* storing them into the buffer pointed to in the first argument.
|
|
* Ensure that each number is between 0 and the third argument.
|
|
* .Pp
|
|
* This function allows a caller to get multiple random numbers at once
|
|
* in a more efficient manner than repeatedly calling
|
|
* .Fn RandInt ,
|
|
* since each call to these functions
|
|
* has to lock and unlock a mutex. It is therefore better to obtain
|
|
* multiple random numbers in one pass if multiple are needed.
|
|
*/
|
|
extern void RandIntN(uint32_t *, size_t, uint32_t);
|
|
|
|
#endif /* CYTOPLASM_RAND_H */
|