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-rw-r--r--gl/windows-mutex.c95
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1/* Plain mutexes (native Windows implementation).
2 Copyright (C) 2005-2023 Free Software Foundation, Inc.
3
4 This file is free software: you can redistribute it and/or modify
5 it under the terms of the GNU Lesser General Public License as
6 published by the Free Software Foundation; either version 2.1 of the
7 License, or (at your option) any later version.
8
9 This file is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public License
15 along with this program. If not, see <https://www.gnu.org/licenses/>. */
16
17/* Written by Bruno Haible <bruno@clisp.org>, 2005.
18 Based on GCC's gthr-win32.h. */
19
20#include <config.h>
21
22/* Specification. */
23#include "windows-mutex.h"
24
25#include <errno.h>
26
27void
28glwthread_mutex_init (glwthread_mutex_t *mutex)
29{
30 InitializeCriticalSection (&mutex->lock);
31 mutex->guard.done = 1;
32}
33
34int
35glwthread_mutex_lock (glwthread_mutex_t *mutex)
36{
37 if (!mutex->guard.done)
38 {
39 if (InterlockedIncrement (&mutex->guard.started) == 0)
40 /* This thread is the first one to need this mutex. Initialize it. */
41 glwthread_mutex_init (mutex);
42 else
43 {
44 /* Don't let mutex->guard.started grow and wrap around. */
45 InterlockedDecrement (&mutex->guard.started);
46 /* Yield the CPU while waiting for another thread to finish
47 initializing this mutex. */
48 while (!mutex->guard.done)
49 Sleep (0);
50 }
51 }
52 EnterCriticalSection (&mutex->lock);
53 return 0;
54}
55
56int
57glwthread_mutex_trylock (glwthread_mutex_t *mutex)
58{
59 if (!mutex->guard.done)
60 {
61 if (InterlockedIncrement (&mutex->guard.started) == 0)
62 /* This thread is the first one to need this mutex. Initialize it. */
63 glwthread_mutex_init (mutex);
64 else
65 {
66 /* Don't let mutex->guard.started grow and wrap around. */
67 InterlockedDecrement (&mutex->guard.started);
68 /* Let another thread finish initializing this mutex, and let it also
69 lock this mutex. */
70 return EBUSY;
71 }
72 }
73 if (!TryEnterCriticalSection (&mutex->lock))
74 return EBUSY;
75 return 0;
76}
77
78int
79glwthread_mutex_unlock (glwthread_mutex_t *mutex)
80{
81 if (!mutex->guard.done)
82 return EINVAL;
83 LeaveCriticalSection (&mutex->lock);
84 return 0;
85}
86
87int
88glwthread_mutex_destroy (glwthread_mutex_t *mutex)
89{
90 if (!mutex->guard.done)
91 return EINVAL;
92 DeleteCriticalSection (&mutex->lock);
93 mutex->guard.done = 0;
94 return 0;
95}