misc/winutils/include/SDL_mutex.h
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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