1/* Copyright (C) 2015-2022 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 33typedef int gomp_sem_t; 34 35static inline void 36gomp_sem_init (gomp_sem_t *sem, int value) 37{ 38 *sem = value; 39} 40 41static inline void 42gomp_sem_destroy (gomp_sem_t *sem) 43{ 44} 45 46static inline void 47gomp_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 60static inline void 61gomp_sem_post (gomp_sem_t *sem) 62{ 63 (void) __atomic_add_fetch (sem, 1, MEMMODEL_RELEASE); 64} 65 66static inline int 67gomp_sem_getcount (gomp_sem_t *sem) 68{ 69 int count = __atomic_load_n (sem, MEMMODEL_RELAXED); 70 if (count < 0) 71 return -1; 72 return count; 73} 74#endif /* GOMP_SEM_H */ 75