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/* Copyright (C) 2015-2022 Free Software Foundation, Inc.
Contributed by Alexander Monakov <amonakov@ispras.ru>
This file is part of the GNU Offloading and Multi Processing Library
(libgomp).
Libgomp is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
Libgomp 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 General Public License for
more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
/* This is an NVPTX specific implementation of a semaphore synchronization
mechanism for libgomp. This type is private to the library. This
semaphore implementation uses atomic instructions and busy waiting. */
#ifndef GOMP_SEM_H
#define GOMP_SEM_H 1
typedef int gomp_sem_t;
static inline void
gomp_sem_init (gomp_sem_t *sem, int value)
{
*sem = value;
}
static inline void
gomp_sem_destroy (gomp_sem_t *sem)
{
}
static inline void
gomp_sem_wait (gomp_sem_t *sem)
{
int count = __atomic_load_n (sem, MEMMODEL_ACQUIRE);
for (;;)
{
while (count == 0)
count = __atomic_load_n (sem, MEMMODEL_ACQUIRE);
if (__atomic_compare_exchange_n (sem, &count, count - 1, false,
MEMMODEL_ACQUIRE, MEMMODEL_RELAXED))
return;
}
}
static inline void
gomp_sem_post (gomp_sem_t *sem)
{
(void) __atomic_add_fetch (sem, 1, MEMMODEL_RELEASE);
}
static inline int
gomp_sem_getcount (gomp_sem_t *sem)
{
int count = __atomic_load_n (sem, MEMMODEL_RELAXED);
if (count < 0)
return -1;
return count;
}
#endif /* GOMP_SEM_H */
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