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 (at) 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 */ 177 178
