1 /* 2 SDL - Simple DirectMedia Layer 3 Copyright (C) 1997-2006 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 /* Functions to provide thread synchronization primitives 27 28 These are independent of the other SDL routines. 29 */ 30 31 #include "SDL_stdinc.h" 32 #include "SDL_error.h" 33 34 #include "begin_code.h" 35 /* Set up for C function definitions, even when using C++ */ 36 #ifdef __cplusplus 37 extern "C" { 38 #endif 39 40 /* Synchronization functions which can time out return this value 41 if they time out. 42 */ 43 #define SDL_MUTEX_TIMEDOUT 1 44 45 /* This is the timeout value which corresponds to never time out */ 46 #define SDL_MUTEX_MAXWAIT (~(Uint32)0) 47 48 49 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ 50 /* Mutex functions */ 51 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ 52 53 /* The SDL mutex structure, defined in SDL_mutex.c */ 54 struct SDL_mutex; 55 typedef struct SDL_mutex SDL_mutex; 56 57 /* Create a mutex, initialized unlocked */ 58 extern DECLSPEC SDL_mutex * SDLCALL SDL_CreateMutex(void); 59 60 /* Lock the mutex (Returns 0, or -1 on error) */ 61 #define SDL_LockMutex(m) SDL_mutexP(m) 62 extern DECLSPEC int SDLCALL SDL_mutexP(SDL_mutex *mutex); 63 64 /* Unlock the mutex (Returns 0, or -1 on error) 65 It is an error to unlock a mutex that has not been locked by 66 the current thread, and doing so results in undefined behavior. 67 */ 68 #define SDL_UnlockMutex(m) SDL_mutexV(m) 69 extern DECLSPEC int SDLCALL SDL_mutexV(SDL_mutex *mutex); 70 71 /* Destroy a mutex */ 72 extern DECLSPEC void SDLCALL SDL_DestroyMutex(SDL_mutex *mutex); 73 74 75 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ 76 /* Semaphore functions */ 77 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ 78 79 /* The SDL semaphore structure, defined in SDL_sem.c */ 80 struct SDL_semaphore; 81 typedef struct SDL_semaphore SDL_sem; 82 83 /* Create a semaphore, initialized with value, returns NULL on failure. */ 84 extern DECLSPEC SDL_sem * SDLCALL SDL_CreateSemaphore(Uint32 initial_value); 85 86 /* Destroy a semaphore */ 87 extern DECLSPEC void SDLCALL SDL_DestroySemaphore(SDL_sem *sem); 88 89 /* This function suspends the calling thread until the semaphore pointed 90 * to by sem has a positive count. It then atomically decreases the semaphore 91 * count. 92 */ 93 extern DECLSPEC int SDLCALL SDL_SemWait(SDL_sem *sem); 94 95 /* Non-blocking variant of SDL_SemWait(), returns 0 if the wait succeeds, 96 SDL_MUTEX_TIMEDOUT if the wait would block, and -1 on error. 97 */ 98 extern DECLSPEC int SDLCALL SDL_SemTryWait(SDL_sem *sem); 99 100 /* Variant of SDL_SemWait() with a timeout in milliseconds, returns 0 if 101 the wait succeeds, SDL_MUTEX_TIMEDOUT if the wait does not succeed in 102 the allotted time, and -1 on error. 103 On some platforms this function is implemented by looping with a delay 104 of 1 ms, and so should be avoided if possible. 105 */ 106 extern DECLSPEC int SDLCALL SDL_SemWaitTimeout(SDL_sem *sem, Uint32 ms); 107 108 /* Atomically increases the semaphore's count (not blocking), returns 0, 109 or -1 on error. 110 */ 111 extern DECLSPEC int SDLCALL SDL_SemPost(SDL_sem *sem); 112 113 /* Returns the current count of the semaphore */ 114 extern DECLSPEC Uint32 SDLCALL SDL_SemValue(SDL_sem *sem); 115 116 117 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ 118 /* Condition variable functions */ 119 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ 120 121 /* The SDL condition variable structure, defined in SDL_cond.c */ 122 struct SDL_cond; 123 typedef struct SDL_cond SDL_cond; 124 125 /* Create a condition variable */ 126 extern DECLSPEC SDL_cond * SDLCALL SDL_CreateCond(void); 127 128 /* Destroy a condition variable */ 129 extern DECLSPEC void SDLCALL SDL_DestroyCond(SDL_cond *cond); 130 131 /* Restart one of the threads that are waiting on the condition variable, 132 returns 0 or -1 on error. 133 */ 134 extern DECLSPEC int SDLCALL SDL_CondSignal(SDL_cond *cond); 135 136 /* Restart all threads that are waiting on the condition variable, 137 returns 0 or -1 on error. 138 */ 139 extern DECLSPEC int SDLCALL SDL_CondBroadcast(SDL_cond *cond); 140 141 /* Wait on the condition variable, unlocking the provided mutex. 142 The mutex must be locked before entering this function! 143 The mutex is re-locked once the condition variable is signaled. 144 Returns 0 when it is signaled, or -1 on error. 145 */ 146 extern DECLSPEC int SDLCALL SDL_CondWait(SDL_cond *cond, SDL_mutex *mut); 147 148 /* Waits for at most 'ms' milliseconds, and returns 0 if the condition 149 variable is signaled, SDL_MUTEX_TIMEDOUT if the condition is not 150 signaled in the allotted time, and -1 on error. 151 On some platforms this function is implemented by looping with a delay 152 of 1 ms, and so should be avoided if possible. 153 */ 154 extern DECLSPEC int SDLCALL SDL_CondWaitTimeout(SDL_cond *cond, SDL_mutex *mutex, Uint32 ms); 155 156 /* Ends C function definitions when using C++ */ 157 #ifdef __cplusplus 158 } 159 #endif 160 #include "close_code.h" 161 162 #endif /* _SDL_mutex_h */ 163