/*
* Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017,
* 2018, 2019
* Jonathan Schleifer <js@heap.zone>
*
* All rights reserved.
*
* This file is part of ObjFW. It may be distributed under the terms of the
* Q Public License 1.0, which can be found in the file LICENSE.QPL included in
* the packaging of this file.
*
* Alternatively, it may be distributed under the terms of the GNU General
* Public License, either version 2 or 3, which can be found in the file
* LICENSE.GPLv2 or LICENSE.GPLv3 respectively included in the packaging of this
* file.
*/
#include "config.h"
#include <stdbool.h>
#import "once.h"
#ifdef OF_AMIGAOS
# include <proto/exec.h>
#endif
#if defined(OF_HAVE_THREADS) && defined(OF_HAVE_ATOMIC_OPS)
# import "atomic.h"
# import "mutex.h"
#endif
void
of_once(of_once_t *control, void (*func)(void))
{
#if !defined(OF_HAVE_THREADS)
if (*control == 0) {
func();
*control = 1;
}
#elif defined(OF_HAVE_PTHREADS)
pthread_once(control, func);
#elif defined(OF_HAVE_ATOMIC_OPS)
/* Avoid atomic operations in case it's already done. */
if (*control == 2)
return;
if (of_atomic_int_cmpswap(control, 0, 1)) {
func();
of_memory_barrier();
of_atomic_int_inc(control);
} else
while (*control == 1)
of_thread_yield();
#elif defined(OF_AMIGAOS)
bool run = false;
/* Avoid Forbid() in case it's already done. */
if (*control == 2)
return;
Forbid();
switch (*control) {
case 0:
*control = 1;
run = true;
break;
case 1:
while (*control == 1) {
Permit();
Forbid();
}
}
Permit();
if (run) {
func();
*control = 2;
}
#else
# error No of_once available
#endif
}