1 /* Copyright (C) 2015-2020 Free Software Foundation, Inc.
2 Contributed by Alexander Monakov <amonakov@ispras.ru>
3
4 This file is part of the GNU Offloading and Multi Processing Library
5 (libgomp).
6
7 Libgomp is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, or (at your option)
10 any later version.
11
12 Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
14 FOR A PARTICULAR PURPOSE. See the GNU General Public License for
15 more details.
16
17 Under Section 7 of GPL version 3, you are granted additional
18 permissions described in the GCC Runtime Library Exception, version
19 3.1, as published by the Free Software Foundation.
20
21 You should have received a copy of the GNU General Public License and
22 a copy of the GCC Runtime Library Exception along with this program;
23 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
24 <http://www.gnu.org/licenses/>. */
25
26 /* This is an NVPTX specific implementation of a semaphore synchronization
27 mechanism for libgomp. This type is private to the library. This
28 semaphore implementation uses atomic instructions and busy waiting. */
29
30 #ifndef GOMP_SEM_H
31 #define GOMP_SEM_H 1
32
33 typedef int gomp_sem_t;
34
35 static inline void
gomp_sem_init(gomp_sem_t * sem,int value)36 gomp_sem_init (gomp_sem_t *sem, int value)
37 {
38 *sem = value;
39 }
40
41 static inline void
gomp_sem_destroy(gomp_sem_t * sem)42 gomp_sem_destroy (gomp_sem_t *sem)
43 {
44 }
45
46 static inline void
gomp_sem_wait(gomp_sem_t * sem)47 gomp_sem_wait (gomp_sem_t *sem)
48 {
49 int count = __atomic_load_n (sem, MEMMODEL_ACQUIRE);
50 for (;;)
51 {
52 while (count == 0)
53 count = __atomic_load_n (sem, MEMMODEL_ACQUIRE);
54 if (__atomic_compare_exchange_n (sem, &count, count - 1, false,
55 MEMMODEL_ACQUIRE, MEMMODEL_RELAXED))
56 return;
57 }
58 }
59
60 static inline void
gomp_sem_post(gomp_sem_t * sem)61 gomp_sem_post (gomp_sem_t *sem)
62 {
63 (void) __atomic_add_fetch (sem, 1, MEMMODEL_RELEASE);
64 }
65 #endif /* GOMP_SEM_H */
66