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