1
0
Fork 0
mirror of https://gitlab.com/sortix/sortix.git synced 2023-02-13 20:55:38 -05:00
sortix--sortix/libc/stdlib/rand.cpp
Jonas 'Sortie' Termansen a1ccba00f7 Thread-secure rand(3).
2014-07-08 17:41:52 +02:00

54 lines
1.7 KiB
C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2014.
This file is part of the Sortix C Library.
The Sortix C Library is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at your
option) any later version.
The Sortix C Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
stdlib/rand.cpp
Returns a random value.
*******************************************************************************/
#include <pthread.h>
#include <stdint.h>
#include <stdlib.h>
static pthread_mutex_t rand_mutex = PTHREAD_MUTEX_INITIALIZER;
static uint32_t m_w = 1337;
static uint32_t m_z = 37;
static uint32_t random_32_bits()
{
m_z = 36969 * (m_z >> 0 & 0xFFFF) + (m_z >> 16 & 0xFFFF);
m_w = 18000 * (m_w >> 0 & 0xFFFF) + (m_w >> 16 & 0xFFFF);
return (m_z << 16) + m_w;
}
extern "C" int rand()
{
pthread_mutex_lock(&rand_mutex);
int result = (int) (random_32_bits() % ((uint32_t) RAND_MAX + 1));
pthread_mutex_unlock(&rand_mutex);
return result;
}
extern "C" void srand(unsigned int seed)
{
pthread_mutex_lock(&rand_mutex);
m_w = seed >> 16 & 0xFFFF;
m_z = seed >> 0 & 0xFFFF;
pthread_mutex_unlock(&rand_mutex);
}