diff options
Diffstat (limited to 'apps/plugins/sdl/src/thread/generic/SDL_sysmutex.c')
-rw-r--r-- | apps/plugins/sdl/src/thread/generic/SDL_sysmutex.c | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/apps/plugins/sdl/src/thread/generic/SDL_sysmutex.c b/apps/plugins/sdl/src/thread/generic/SDL_sysmutex.c new file mode 100644 index 0000000000..ecfea876a5 --- /dev/null +++ b/apps/plugins/sdl/src/thread/generic/SDL_sysmutex.c | |||
@@ -0,0 +1,129 @@ | |||
1 | /* | ||
2 | SDL - Simple DirectMedia Layer | ||
3 | Copyright (C) 1997-2012 Sam Lantinga | ||
4 | |||
5 | This library is free software; you can redistribute it and/or | ||
6 | modify it under the terms of the GNU Lesser General Public | ||
7 | License as published by the Free Software Foundation; either | ||
8 | version 2.1 of the License, or (at your option) any later version. | ||
9 | |||
10 | This library is distributed in the hope that it will be useful, | ||
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
13 | Lesser General Public License for more details. | ||
14 | |||
15 | You should have received a copy of the GNU Lesser General Public | ||
16 | License along with this library; if not, write to the Free Software | ||
17 | Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA | ||
18 | |||
19 | Sam Lantinga | ||
20 | slouken@libsdl.org | ||
21 | */ | ||
22 | #include "SDL_config.h" | ||
23 | |||
24 | /* An implementation of mutexes using semaphores */ | ||
25 | |||
26 | #include "SDL_thread.h" | ||
27 | #include "SDL_systhread_c.h" | ||
28 | |||
29 | |||
30 | struct SDL_mutex { | ||
31 | int recursive; | ||
32 | Uint32 owner; | ||
33 | SDL_sem *sem; | ||
34 | }; | ||
35 | |||
36 | /* Create a mutex */ | ||
37 | SDL_mutex *SDL_CreateMutex(void) | ||
38 | { | ||
39 | SDL_mutex *mutex; | ||
40 | |||
41 | /* Allocate mutex memory */ | ||
42 | mutex = (SDL_mutex *)SDL_malloc(sizeof(*mutex)); | ||
43 | if ( mutex ) { | ||
44 | /* Create the mutex semaphore, with initial value 1 */ | ||
45 | mutex->sem = SDL_CreateSemaphore(1); | ||
46 | mutex->recursive = 0; | ||
47 | mutex->owner = 0; | ||
48 | if ( ! mutex->sem ) { | ||
49 | SDL_free(mutex); | ||
50 | mutex = NULL; | ||
51 | } | ||
52 | } else { | ||
53 | SDL_OutOfMemory(); | ||
54 | } | ||
55 | return mutex; | ||
56 | } | ||
57 | |||
58 | /* Free the mutex */ | ||
59 | void SDL_DestroyMutex(SDL_mutex *mutex) | ||
60 | { | ||
61 | if ( mutex ) { | ||
62 | if ( mutex->sem ) { | ||
63 | SDL_DestroySemaphore(mutex->sem); | ||
64 | } | ||
65 | SDL_free(mutex); | ||
66 | } | ||
67 | } | ||
68 | |||
69 | /* Lock the semaphore */ | ||
70 | int SDL_mutexP(SDL_mutex *mutex) | ||
71 | { | ||
72 | #if SDL_THREADS_DISABLED | ||
73 | return 0; | ||
74 | #else | ||
75 | Uint32 this_thread; | ||
76 | |||
77 | if ( mutex == NULL ) { | ||
78 | SDL_SetError("Passed a NULL mutex"); | ||
79 | return -1; | ||
80 | } | ||
81 | |||
82 | this_thread = SDL_ThreadID(); | ||
83 | if ( mutex->owner == this_thread ) { | ||
84 | ++mutex->recursive; | ||
85 | } else { | ||
86 | /* The order of operations is important. | ||
87 | We set the locking thread id after we obtain the lock | ||
88 | so unlocks from other threads will fail. | ||
89 | */ | ||
90 | SDL_SemWait(mutex->sem); | ||
91 | mutex->owner = this_thread; | ||
92 | mutex->recursive = 0; | ||
93 | } | ||
94 | |||
95 | return 0; | ||
96 | #endif /* SDL_THREADS_DISABLED */ | ||
97 | } | ||
98 | |||
99 | /* Unlock the mutex */ | ||
100 | int SDL_mutexV(SDL_mutex *mutex) | ||
101 | { | ||
102 | #if SDL_THREADS_DISABLED | ||
103 | return 0; | ||
104 | #else | ||
105 | if ( mutex == NULL ) { | ||
106 | SDL_SetError("Passed a NULL mutex"); | ||
107 | return -1; | ||
108 | } | ||
109 | |||
110 | /* If we don't own the mutex, we can't unlock it */ | ||
111 | if ( SDL_ThreadID() != mutex->owner ) { | ||
112 | SDL_SetError("mutex not owned by this thread"); | ||
113 | return -1; | ||
114 | } | ||
115 | |||
116 | if ( mutex->recursive ) { | ||
117 | --mutex->recursive; | ||
118 | } else { | ||
119 | /* The order of operations is important. | ||
120 | First reset the owner so another thread doesn't lock | ||
121 | the mutex and set the ownership before we reset it, | ||
122 | then release the lock semaphore. | ||
123 | */ | ||
124 | mutex->owner = 0; | ||
125 | SDL_SemPost(mutex->sem); | ||
126 | } | ||
127 | return 0; | ||
128 | #endif /* SDL_THREADS_DISABLED */ | ||
129 | } | ||