include/SDL_mutex.h
author Sam Lantinga <slouken@libsdl.org>
Mon, 10 Jul 2006 21:04:37 +0000
changeset 1895 c121d94672cb
parent 1358 c71e05b4dc2e
child 2859 99210400e8b9
permissions -rw-r--r--
SDL 1.2 is moving to a branch, and SDL 1.3 is becoming the head.
     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 /**
    27  * \file SDL_mutex.h
    28  *
    29  * Functions to provide thread synchronization primitives
    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 /* *INDENT-OFF* */
    39 extern "C" {
    40 /* *INDENT-ON* */
    41 #endif
    42 
    43 /* Synchronization functions which can time out return this value
    44    if they time out.
    45 */
    46 #define SDL_MUTEX_TIMEDOUT	1
    47 
    48 /* This is the timeout value which corresponds to never time out */
    49 #define SDL_MUTEX_MAXWAIT	(~(Uint32)0)
    50 
    51 
    52 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
    53 /* Mutex functions                                               */
    54 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
    55 
    56 /* The SDL mutex structure, defined in SDL_mutex.c */
    57 struct SDL_mutex;
    58 typedef struct SDL_mutex SDL_mutex;
    59 
    60 /* Create a mutex, initialized unlocked */
    61 extern DECLSPEC SDL_mutex *SDLCALL SDL_CreateMutex(void);
    62 
    63 /* Lock the mutex  (Returns 0, or -1 on error) */
    64 #define SDL_LockMutex(m)	SDL_mutexP(m)
    65 extern DECLSPEC int SDLCALL SDL_mutexP(SDL_mutex * mutex);
    66 
    67 /* Unlock the mutex  (Returns 0, or -1 on error)
    68    It is an error to unlock a mutex that has not been locked by
    69    the current thread, and doing so results in undefined behavior.
    70  */
    71 #define SDL_UnlockMutex(m)	SDL_mutexV(m)
    72 extern DECLSPEC int SDLCALL SDL_mutexV(SDL_mutex * mutex);
    73 
    74 /* Destroy a mutex */
    75 extern DECLSPEC void SDLCALL SDL_DestroyMutex(SDL_mutex * mutex);
    76 
    77 
    78 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
    79 /* Semaphore functions                                           */
    80 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
    81 
    82 /* The SDL semaphore structure, defined in SDL_sem.c */
    83 struct SDL_semaphore;
    84 typedef struct SDL_semaphore SDL_sem;
    85 
    86 /* Create a semaphore, initialized with value, returns NULL on failure. */
    87 extern DECLSPEC SDL_sem *SDLCALL SDL_CreateSemaphore(Uint32 initial_value);
    88 
    89 /* Destroy a semaphore */
    90 extern DECLSPEC void SDLCALL SDL_DestroySemaphore(SDL_sem * sem);
    91 
    92 /* This function suspends the calling thread until the semaphore pointed 
    93  * to by sem has a positive count. It then atomically decreases the semaphore
    94  * count.
    95  */
    96 extern DECLSPEC int SDLCALL SDL_SemWait(SDL_sem * sem);
    97 
    98 /* Non-blocking variant of SDL_SemWait(), returns 0 if the wait succeeds,
    99    SDL_MUTEX_TIMEDOUT if the wait would block, and -1 on error.
   100 */
   101 extern DECLSPEC int SDLCALL SDL_SemTryWait(SDL_sem * sem);
   102 
   103 /* Variant of SDL_SemWait() with a timeout in milliseconds, returns 0 if
   104    the wait succeeds, SDL_MUTEX_TIMEDOUT if the wait does not succeed in
   105    the allotted time, and -1 on error.
   106    On some platforms this function is implemented by looping with a delay
   107    of 1 ms, and so should be avoided if possible.
   108 */
   109 extern DECLSPEC int SDLCALL SDL_SemWaitTimeout(SDL_sem * sem, Uint32 ms);
   110 
   111 /* Atomically increases the semaphore's count (not blocking), returns 0,
   112    or -1 on error.
   113  */
   114 extern DECLSPEC int SDLCALL SDL_SemPost(SDL_sem * sem);
   115 
   116 /* Returns the current count of the semaphore */
   117 extern DECLSPEC Uint32 SDLCALL SDL_SemValue(SDL_sem * sem);
   118 
   119 
   120 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
   121 /* Condition variable functions                                  */
   122 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
   123 
   124 /* The SDL condition variable structure, defined in SDL_cond.c */
   125 struct SDL_cond;
   126 typedef struct SDL_cond SDL_cond;
   127 
   128 /* Create a condition variable */
   129 extern DECLSPEC SDL_cond *SDLCALL SDL_CreateCond(void);
   130 
   131 /* Destroy a condition variable */
   132 extern DECLSPEC void SDLCALL SDL_DestroyCond(SDL_cond * cond);
   133 
   134 /* Restart one of the threads that are waiting on the condition variable,
   135    returns 0 or -1 on error.
   136  */
   137 extern DECLSPEC int SDLCALL SDL_CondSignal(SDL_cond * cond);
   138 
   139 /* Restart all threads that are waiting on the condition variable,
   140    returns 0 or -1 on error.
   141  */
   142 extern DECLSPEC int SDLCALL SDL_CondBroadcast(SDL_cond * cond);
   143 
   144 /* Wait on the condition variable, unlocking the provided mutex.
   145    The mutex must be locked before entering this function!
   146    The mutex is re-locked once the condition variable is signaled.
   147    Returns 0 when it is signaled, or -1 on error.
   148  */
   149 extern DECLSPEC int SDLCALL SDL_CondWait(SDL_cond * cond, SDL_mutex * mut);
   150 
   151 /* Waits for at most 'ms' milliseconds, and returns 0 if the condition
   152    variable is signaled, SDL_MUTEX_TIMEDOUT if the condition is not
   153    signaled in the allotted time, and -1 on error.
   154    On some platforms this function is implemented by looping with a delay
   155    of 1 ms, and so should be avoided if possible.
   156 */
   157 extern DECLSPEC int SDLCALL SDL_CondWaitTimeout(SDL_cond * cond,
   158                                                 SDL_mutex * mutex, Uint32 ms);
   159 
   160 /* Ends C function definitions when using C++ */
   161 #ifdef __cplusplus
   162 /* *INDENT-OFF* */
   163 }
   164 /* *INDENT-ON* */
   165 #endif
   166 #include "close_code.h"
   167 
   168 #endif /* _SDL_mutex_h */
   169 
   170 /* vi: set ts=4 sw=4 expandtab: */