e14743d1 |
1 | /* |
2 | SDL - Simple DirectMedia Layer |
3 | Copyright (C) 1997-2009 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 | |
23 | #ifndef _SDL_mutex_h |
24 | #define _SDL_mutex_h |
25 | |
26 | /** @file SDL_mutex.h |
27 | * Functions to provide thread synchronization primitives |
28 | * |
29 | * @note These are independent of the other SDL routines. |
30 | */ |
31 | |
32 | #include "SDL_stdinc.h" |
33 | #include "SDL_error.h" |
34 | |
35 | #include "begin_code.h" |
36 | /* Set up for C function definitions, even when using C++ */ |
37 | #ifdef __cplusplus |
38 | extern "C" { |
39 | #endif |
40 | |
41 | /** Synchronization functions which can time out return this value |
42 | * if they time out. |
43 | */ |
44 | #define SDL_MUTEX_TIMEDOUT 1 |
45 | |
46 | /** This is the timeout value which corresponds to never time out */ |
47 | #define SDL_MUTEX_MAXWAIT (~(Uint32)0) |
48 | |
49 | |
50 | /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ |
51 | /** @name Mutex functions */ /*@{*/ |
52 | /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ |
53 | |
54 | /** The SDL mutex structure, defined in SDL_mutex.c */ |
55 | struct SDL_mutex; |
56 | typedef struct SDL_mutex SDL_mutex; |
57 | |
58 | /** Create a mutex, initialized unlocked */ |
59 | extern DECLSPEC SDL_mutex * SDLCALL SDL_CreateMutex(void); |
60 | |
61 | #define SDL_LockMutex(m) SDL_mutexP(m) |
62 | /** Lock the mutex |
63 | * @return 0, or -1 on error |
64 | */ |
65 | extern DECLSPEC int SDLCALL SDL_mutexP(SDL_mutex *mutex); |
66 | |
67 | #define SDL_UnlockMutex(m) SDL_mutexV(m) |
68 | /** Unlock the mutex |
69 | * @return 0, or -1 on error |
70 | * |
71 | * It is an error to unlock a mutex that has not been locked by |
72 | * the current thread, and doing so results in undefined behavior. |
73 | */ |
74 | extern DECLSPEC int SDLCALL SDL_mutexV(SDL_mutex *mutex); |
75 | |
76 | /** Destroy a mutex */ |
77 | extern DECLSPEC void SDLCALL SDL_DestroyMutex(SDL_mutex *mutex); |
78 | |
79 | /*@}*/ |
80 | |
81 | /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ |
82 | /** @name Semaphore functions */ /*@{*/ |
83 | /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ |
84 | |
85 | /** The SDL semaphore structure, defined in SDL_sem.c */ |
86 | struct SDL_semaphore; |
87 | typedef struct SDL_semaphore SDL_sem; |
88 | |
89 | /** Create a semaphore, initialized with value, returns NULL on failure. */ |
90 | extern DECLSPEC SDL_sem * SDLCALL SDL_CreateSemaphore(Uint32 initial_value); |
91 | |
92 | /** Destroy a semaphore */ |
93 | extern DECLSPEC void SDLCALL SDL_DestroySemaphore(SDL_sem *sem); |
94 | |
95 | /** |
96 | * This function suspends the calling thread until the semaphore pointed |
97 | * to by sem has a positive count. It then atomically decreases the semaphore |
98 | * count. |
99 | */ |
100 | extern DECLSPEC int SDLCALL SDL_SemWait(SDL_sem *sem); |
101 | |
102 | /** Non-blocking variant of SDL_SemWait(). |
103 | * @return 0 if the wait succeeds, |
104 | * SDL_MUTEX_TIMEDOUT if the wait would block, and -1 on error. |
105 | */ |
106 | extern DECLSPEC int SDLCALL SDL_SemTryWait(SDL_sem *sem); |
107 | |
108 | /** Variant of SDL_SemWait() with a timeout in milliseconds, returns 0 if |
109 | * the wait succeeds, SDL_MUTEX_TIMEDOUT if the wait does not succeed in |
110 | * the allotted time, and -1 on error. |
111 | * |
112 | * On some platforms this function is implemented by looping with a delay |
113 | * of 1 ms, and so should be avoided if possible. |
114 | */ |
115 | extern DECLSPEC int SDLCALL SDL_SemWaitTimeout(SDL_sem *sem, Uint32 ms); |
116 | |
117 | /** Atomically increases the semaphore's count (not blocking). |
118 | * @return 0, or -1 on error. |
119 | */ |
120 | extern DECLSPEC int SDLCALL SDL_SemPost(SDL_sem *sem); |
121 | |
122 | /** Returns the current count of the semaphore */ |
123 | extern DECLSPEC Uint32 SDLCALL SDL_SemValue(SDL_sem *sem); |
124 | |
125 | /*@}*/ |
126 | |
127 | /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ |
128 | /** @name Condition_variable_functions */ /*@{*/ |
129 | /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ |
130 | |
131 | /*@{*/ |
132 | /** The SDL condition variable structure, defined in SDL_cond.c */ |
133 | struct SDL_cond; |
134 | typedef struct SDL_cond SDL_cond; |
135 | /*@}*/ |
136 | |
137 | /** Create a condition variable */ |
138 | extern DECLSPEC SDL_cond * SDLCALL SDL_CreateCond(void); |
139 | |
140 | /** Destroy a condition variable */ |
141 | extern DECLSPEC void SDLCALL SDL_DestroyCond(SDL_cond *cond); |
142 | |
143 | /** Restart one of the threads that are waiting on the condition variable, |
144 | * @return 0 or -1 on error. |
145 | */ |
146 | extern DECLSPEC int SDLCALL SDL_CondSignal(SDL_cond *cond); |
147 | |
148 | /** Restart all threads that are waiting on the condition variable, |
149 | * @return 0 or -1 on error. |
150 | */ |
151 | extern DECLSPEC int SDLCALL SDL_CondBroadcast(SDL_cond *cond); |
152 | |
153 | /** Wait on the condition variable, unlocking the provided mutex. |
154 | * The mutex must be locked before entering this function! |
155 | * The mutex is re-locked once the condition variable is signaled. |
156 | * @return 0 when it is signaled, or -1 on error. |
157 | */ |
158 | extern DECLSPEC int SDLCALL SDL_CondWait(SDL_cond *cond, SDL_mutex *mut); |
159 | |
160 | /** Waits for at most 'ms' milliseconds, and returns 0 if the condition |
161 | * variable is signaled, SDL_MUTEX_TIMEDOUT if the condition is not |
162 | * signaled in the allotted time, and -1 on error. |
163 | * On some platforms this function is implemented by looping with a delay |
164 | * of 1 ms, and so should be avoided if possible. |
165 | */ |
166 | extern DECLSPEC int SDLCALL SDL_CondWaitTimeout(SDL_cond *cond, SDL_mutex *mutex, Uint32 ms); |
167 | |
168 | /*@}*/ |
169 | |
170 | /* Ends C function definitions when using C++ */ |
171 | #ifdef __cplusplus |
172 | } |
173 | #endif |
174 | #include "close_code.h" |
175 | |
176 | #endif /* _SDL_mutex_h */ |
177 | |