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  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.  
  178.