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 */