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99dee823 | 1 | /* Copyright (C) 2015-2021 Free Software Foundation, Inc. |
6103184e AM |
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 mutex synchronization | |
27 | mechanism for libgomp. This type is private to the library. This | |
28 | implementation uses atomic instructions and busy waiting. | |
29 | ||
30 | A ptrlock has four states: | |
31 | 0/NULL Initial | |
32 | 1 Owned by me, I get to write a pointer to ptrlock. | |
33 | 2 Some thread is waiting on the ptrlock. | |
34 | >2 Ptrlock contains a valid pointer. | |
35 | It is not valid to gain the ptrlock and then write a NULL to it. */ | |
36 | ||
37 | #ifndef GOMP_PTRLOCK_H | |
38 | #define GOMP_PTRLOCK_H 1 | |
39 | ||
40 | typedef void *gomp_ptrlock_t; | |
41 | ||
42 | static inline void gomp_ptrlock_init (gomp_ptrlock_t *ptrlock, void *ptr) | |
43 | { | |
44 | *ptrlock = ptr; | |
45 | } | |
46 | ||
47 | static inline void *gomp_ptrlock_get (gomp_ptrlock_t *ptrlock) | |
48 | { | |
49 | uintptr_t v = (uintptr_t) __atomic_load_n (ptrlock, MEMMODEL_ACQUIRE); | |
50 | if (v > 2) | |
51 | return (void *) v; | |
52 | ||
53 | if (v == 0 | |
54 | && __atomic_compare_exchange_n (ptrlock, &v, 1, false, | |
55 | MEMMODEL_ACQUIRE, MEMMODEL_ACQUIRE)) | |
56 | return NULL; | |
57 | ||
58 | while (v == 1) | |
59 | v = (uintptr_t) __atomic_load_n (ptrlock, MEMMODEL_ACQUIRE); | |
60 | ||
61 | return (void *) v; | |
62 | } | |
63 | ||
64 | static inline void gomp_ptrlock_set (gomp_ptrlock_t *ptrlock, void *ptr) | |
65 | { | |
66 | __atomic_store_n (ptrlock, ptr, MEMMODEL_RELEASE); | |
67 | } | |
68 | ||
69 | static inline void gomp_ptrlock_destroy (gomp_ptrlock_t *ptrlock) | |
70 | { | |
71 | } | |
72 | ||
73 | #endif /* GOMP_PTRLOCK_H */ |