include/SDL_mutex.h
author Sam Lantinga <slouken@libsdl.org>
Fri, 10 Feb 2006 03:19:02 +0000
changeset 1356 67114343400d
parent 1312 c9b51268668f
child 1358 c71e05b4dc2e
permissions -rw-r--r--
*** empty log message ***
     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 
    33 #include "begin_code.h"
    34 /* Set up for C function definitions, even when using C++ */
    35 #ifdef __cplusplus
    36 extern "C" {
    37 #endif
    38 
    39 /* Synchronization functions which can time out return this value
    40    if they time out.
    41 */
    42 #define SDL_MUTEX_TIMEDOUT	1
    43 
    44 /* This is the timeout value which corresponds to never time out */
    45 #define SDL_MUTEX_MAXWAIT	(~(Uint32)0)
    46 
    47 
    48 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
    49 /* Mutex functions                                               */
    50 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
    51 
    52 /* The SDL mutex structure, defined in SDL_mutex.c */
    53 struct SDL_mutex;
    54 typedef struct SDL_mutex SDL_mutex;
    55 
    56 /* Create a mutex, initialized unlocked */
    57 extern DECLSPEC SDL_mutex * SDLCALL SDL_CreateMutex(void);
    58 
    59 /* Lock the mutex  (Returns 0, or -1 on error) */
    60 #define SDL_LockMutex(m)	SDL_mutexP(m)
    61 extern DECLSPEC int SDLCALL SDL_mutexP(SDL_mutex *mutex);
    62 
    63 /* Unlock the mutex  (Returns 0, or -1 on error)
    64    It is an error to unlock a mutex that has not been locked by
    65    the current thread, and doing so results in undefined behavior.
    66  */
    67 #define SDL_UnlockMutex(m)	SDL_mutexV(m)
    68 extern DECLSPEC int SDLCALL SDL_mutexV(SDL_mutex *mutex);
    69 
    70 /* Destroy a mutex */
    71 extern DECLSPEC void SDLCALL SDL_DestroyMutex(SDL_mutex *mutex);
    72 
    73 
    74 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
    75 /* Semaphore functions                                           */
    76 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
    77 
    78 /* The SDL semaphore structure, defined in SDL_sem.c */
    79 struct SDL_semaphore;
    80 typedef struct SDL_semaphore SDL_sem;
    81 
    82 /* Create a semaphore, initialized with value, returns NULL on failure. */
    83 extern DECLSPEC SDL_sem * SDLCALL SDL_CreateSemaphore(Uint32 initial_value);
    84 
    85 /* Destroy a semaphore */
    86 extern DECLSPEC void SDLCALL SDL_DestroySemaphore(SDL_sem *sem);
    87 
    88 /* This function suspends the calling thread until the semaphore pointed 
    89  * to by sem has a positive count. It then atomically decreases the semaphore
    90  * count.
    91  */
    92 extern DECLSPEC int SDLCALL SDL_SemWait(SDL_sem *sem);
    93 
    94 /* Non-blocking variant of SDL_SemWait(), returns 0 if the wait succeeds,
    95    SDL_MUTEX_TIMEDOUT if the wait would block, and -1 on error.
    96 */
    97 extern DECLSPEC int SDLCALL SDL_SemTryWait(SDL_sem *sem);
    98 
    99 /* Variant of SDL_SemWait() with a timeout in milliseconds, returns 0 if
   100    the wait succeeds, SDL_MUTEX_TIMEDOUT if the wait does not succeed in
   101    the allotted time, and -1 on error.
   102    On some platforms this function is implemented by looping with a delay
   103    of 1 ms, and so should be avoided if possible.
   104 */
   105 extern DECLSPEC int SDLCALL SDL_SemWaitTimeout(SDL_sem *sem, Uint32 ms);
   106 
   107 /* Atomically increases the semaphore's count (not blocking), returns 0,
   108    or -1 on error.
   109  */
   110 extern DECLSPEC int SDLCALL SDL_SemPost(SDL_sem *sem);
   111 
   112 /* Returns the current count of the semaphore */
   113 extern DECLSPEC Uint32 SDLCALL SDL_SemValue(SDL_sem *sem);
   114 
   115 
   116 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
   117 /* Condition variable functions                                  */
   118 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
   119 
   120 /* The SDL condition variable structure, defined in SDL_cond.c */
   121 struct SDL_cond;
   122 typedef struct SDL_cond SDL_cond;
   123 
   124 /* Create a condition variable */
   125 extern DECLSPEC SDL_cond * SDLCALL SDL_CreateCond(void);
   126 
   127 /* Destroy a condition variable */
   128 extern DECLSPEC void SDLCALL SDL_DestroyCond(SDL_cond *cond);
   129 
   130 /* Restart one of the threads that are waiting on the condition variable,
   131    returns 0 or -1 on error.
   132  */
   133 extern DECLSPEC int SDLCALL SDL_CondSignal(SDL_cond *cond);
   134 
   135 /* Restart all threads that are waiting on the condition variable,
   136    returns 0 or -1 on error.
   137  */
   138 extern DECLSPEC int SDLCALL SDL_CondBroadcast(SDL_cond *cond);
   139 
   140 /* Wait on the condition variable, unlocking the provided mutex.
   141    The mutex must be locked before entering this function!
   142    The mutex is re-locked once the condition variable is signaled.
   143    Returns 0 when it is signaled, or -1 on error.
   144  */
   145 extern DECLSPEC int SDLCALL SDL_CondWait(SDL_cond *cond, SDL_mutex *mut);
   146 
   147 /* Waits for at most 'ms' milliseconds, and returns 0 if the condition
   148    variable is signaled, SDL_MUTEX_TIMEDOUT if the condition is not
   149    signaled in the allotted time, and -1 on error.
   150    On some platforms this function is implemented by looping with a delay
   151    of 1 ms, and so should be avoided if possible.
   152 */
   153 extern DECLSPEC int SDLCALL SDL_CondWaitTimeout(SDL_cond *cond, SDL_mutex *mutex, Uint32 ms);
   154 
   155 /* Ends C function definitions when using C++ */
   156 #ifdef __cplusplus
   157 }
   158 #endif
   159 #include "close_code.h"
   160 
   161 #endif /* _SDL_mutex_h */