src/include/SDL_mutex.h

   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 */