zenilib: zenilib/jni/external/sdl/src/thread/generic/SDL_sysmutex.c Source File

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SDL_sysmutex.c
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1 /*
2 Simple DirectMedia Layer
3 Copyright (C) 1997-2013 Sam Lantinga <slouken@libsdl.org>
4
5 This software is provided 'as-is', without any express or implied
6 warranty. In no event will the authors be held liable for any damages
7 arising from the use of this software.
8
9 Permission is granted to anyone to use this software for any purpose,
10 including commercial applications, and to alter it and redistribute it
11 freely, subject to the following restrictions:
12
13 1. The origin of this software must not be misrepresented; you must not
14 claim that you wrote the original software. If you use this software
15 in a product, an acknowledgment in the product documentation would be
16 appreciated but is not required.
17 2. Altered source versions must be plainly marked as such, and must not be
18 misrepresented as being the original software.
19 3. This notice may not be removed or altered from any source distribution.
20 */
21 #include "SDL_config.h"
22
23 /* An implementation of mutexes using semaphores */
24
25 #include "SDL_thread.h"
26 #include "SDL_systhread_c.h"
27
28
29 struct SDL_mutex
30 {
31 int recursive;
32 SDL_threadID owner;
33 SDL_sem *sem;
34 };
35
36 /* Create a mutex */
37 SDL_mutex *
38 SDL_CreateMutex(void)
39 {
40 SDL_mutex *mutex;
41
42 /* Allocate mutex memory */
43 mutex = (SDL_mutex *) SDL_malloc(sizeof(*mutex));
44 if (mutex) {
45 /* Create the mutex semaphore, with initial value 1 */
46 mutex->sem = SDL_CreateSemaphore(1);
47 mutex->recursive = 0;
48 mutex->owner = 0;
49 if (!mutex->sem) {
50 SDL_free(mutex);
51 mutex = NULL;
52 }
53 } else {
54 SDL_OutOfMemory();
55 }
56 return mutex;
57 }
58
59 /* Free the mutex */
60 void
61 SDL_DestroyMutex(SDL_mutex * mutex)
62 {
63 if (mutex) {
64 if (mutex->sem) {
65 SDL_DestroySemaphore(mutex->sem);
66 }
67 SDL_free(mutex);
68 }
69 }
70
71 /* Lock the mutex */
72 int
73 SDL_LockMutex(SDL_mutex * mutex)
74 {
75 #if SDL_THREADS_DISABLED
76 return 0;
77 #else
78 SDL_threadID this_thread;
79
80 if (mutex == NULL) {
81 return SDL_SetError("Passed a NULL mutex");
82 }
83
84 this_thread = SDL_ThreadID();
85 if (mutex->owner == this_thread) {
86 ++mutex->recursive;
87 } else {
88 /* The order of operations is important.
89 We set the locking thread id after we obtain the lock
90 so unlocks from other threads will fail.
91 */
92 SDL_SemWait(mutex->sem);
93 mutex->owner = this_thread;
94 mutex->recursive = 0;
95 }
96
97 return 0;
98 #endif /* SDL_THREADS_DISABLED */
99 }
100
101 /* try Lock the mutex */
102 int
103 SDL_TryLockMutex(SDL_mutex * mutex)
104 {
105 #if SDL_THREADS_DISABLED
106 return 0;
107 #else
108 int retval = 0;
109 SDL_threadID this_thread;
110
111 if (mutex == NULL) {
112 return SDL_SetError("Passed a NULL mutex");
113 }
114
115 this_thread = SDL_ThreadID();
116 if (mutex->owner == this_thread) {
117 ++mutex->recursive;
118 } else {
119 /* The order of operations is important.
120 We set the locking thread id after we obtain the lock
121 so unlocks from other threads will fail.
122 */
123 retval = SDL_SemWait(mutex->sem);
124 if (retval == 0) {
125 mutex->owner = this_thread;
126 mutex->recursive = 0;
127 }
128 }
129
130 return retval;
131 #endif /* SDL_THREADS_DISABLED */
132 }
133
134 /* Unlock the mutex */
135 int
136 SDL_mutexV(SDL_mutex * mutex)
137 {
138 #if SDL_THREADS_DISABLED
139 return 0;
140 #else
141 if (mutex == NULL) {
142 return SDL_SetError("Passed a NULL mutex");
143 }
144
145 /* If we don't own the mutex, we can't unlock it */
146 if (SDL_ThreadID() != mutex->owner) {
147 return SDL_SetError("mutex not owned by this thread");
148 }
149
150 if (mutex->recursive) {
151 --mutex->recursive;
152 } else {
153 /* The order of operations is important.
154 First reset the owner so another thread doesn't lock
155 the mutex and set the ownership before we reset it,
156 then release the lock semaphore.
157 */
158 mutex->owner = 0;
159 SDL_SemPost(mutex->sem);
160 }
161 return 0;
162 #endif /* SDL_THREADS_DISABLED */
163 }
164
165 /* vi: set ts=4 sw=4 expandtab: */
SDL_CreateSemaphore
DECLSPEC SDL_sem *SDLCALL SDL_CreateSemaphore(Uint32 initial_value)
Definition: SDL_syssem.c:85
SDL_systhread_c.h
SDL_ThreadID
DECLSPEC SDL_threadID SDLCALL SDL_ThreadID(void)
Definition: SDL_systhread.c:48
SDL_threadID
unsigned long SDL_threadID
Definition: SDL_thread.h:49
SDL_sem
struct SDL_semaphore SDL_sem
Definition: SDL_mutex.h:107
NULL
#define NULL
Definition: ftobjs.h:61
SDL_LockMutex
DECLSPEC int SDLCALL SDL_LockMutex(SDL_mutex *mutex)
Definition: SDL_sysmutex.c:73
SDL_SemWait
DECLSPEC int SDLCALL SDL_SemWait(SDL_sem *sem)
Definition: SDL_syssem.c:180
SDL_CreateMutex
DECLSPEC SDL_mutex *SDLCALL SDL_CreateMutex(void)
Definition: SDL_sysmutex.c:38
SDL_free
DECLSPEC void SDLCALL SDL_free(void *mem)
SDL_config.h
SDL_mutexV
#define SDL_mutexV(m)
Definition: SDL_mutex.h:89
SDL_TryLockMutex
DECLSPEC int SDLCALL SDL_TryLockMutex(SDL_mutex *mutex)
Definition: SDL_sysmutex.c:103
SDL_SetError
DECLSPEC int SDLCALL SDL_SetError(const char *fmt,...)
Definition: SDL_error.c:53
SDL_malloc
DECLSPEC void *SDLCALL SDL_malloc(size_t size)
SDL_DestroySemaphore
DECLSPEC void SDLCALL SDL_DestroySemaphore(SDL_sem *sem)
Definition: SDL_syssem.c:111
SDL_OutOfMemory
#define SDL_OutOfMemory()
Definition: SDL_error.h:52
SDL_mutex
struct SDL_mutex SDL_mutex
Definition: SDL_mutex.h:59
SDL_DestroyMutex
DECLSPEC void SDLCALL SDL_DestroyMutex(SDL_mutex *mutex)
Definition: SDL_sysmutex.c:61
SDL_SemPost
DECLSPEC int SDLCALL SDL_SemPost(SDL_sem *sem)
Definition: SDL_syssem.c:200