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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 mutex synchronization
- mechanism for libgomp. This type is private to the library. This
- implementation uses atomic instructions and busy waiting.
- A ptrlock has four states:
- 0/NULL Initial
- 1 Owned by me, I get to write a pointer to ptrlock.
- 2 Some thread is waiting on the ptrlock.
- >2 Ptrlock contains a valid pointer.
- It is not valid to gain the ptrlock and then write a NULL to it. */
- #ifndef GOMP_PTRLOCK_H
- #define GOMP_PTRLOCK_H 1
- typedef void *gomp_ptrlock_t;
- static inline void gomp_ptrlock_init (gomp_ptrlock_t *ptrlock, void *ptr)
- {
- *ptrlock = ptr;
- }
- static inline void *gomp_ptrlock_get (gomp_ptrlock_t *ptrlock)
- {
- uintptr_t v = (uintptr_t) __atomic_load_n (ptrlock, MEMMODEL_ACQUIRE);
- if (v > 2)
- return (void *) v;
- if (v == 0
- && __atomic_compare_exchange_n (ptrlock, &v, 1, false,
- MEMMODEL_ACQUIRE, MEMMODEL_ACQUIRE))
- return NULL;
- while (v == 1)
- v = (uintptr_t) __atomic_load_n (ptrlock, MEMMODEL_ACQUIRE);
- return (void *) v;
- }
- static inline void gomp_ptrlock_set (gomp_ptrlock_t *ptrlock, void *ptr)
- {
- __atomic_store_n (ptrlock, ptr, MEMMODEL_RELEASE);
- }
- static inline void gomp_ptrlock_destroy (gomp_ptrlock_t *ptrlock)
- {
- }
- #endif /* GOMP_PTRLOCK_H */
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