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