FUNCTIONS

1. SDL_LockMutex
2. SDL_UnlockMutex

   1 /*
   2     SDL - Simple DirectMedia Layer
   3     Copyright (C) 1997, 1998, 1999, 2000, 2001  Sam Lantinga
   4 
   5     This library is free software; you can redistribute it and/or
   6     modify it under the terms of the GNU Library General Public
   7     License as published by the Free Software Foundation; either
   8     version 2 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     Library General Public License for more details.
  14 
  15     You should have received a copy of the GNU Library General Public
  16     License along with this library; if not, write to the Free
  17     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18 
  19     Sam Lantinga
  20     slouken@devolution.com
  21 */
  23 #ifdef SAVE_RCSID
  24 static char rcsid =
  25  "@(#) $Id: SDL_mutex.h,v 1.5.2.8 2001/02/17 01:45:30 hercules Exp $";
  26 #endif
  28 #ifndef _SDL_mutex_h
  29 #define _SDL_mutex_h
  31 /* Functions to provide thread synchronization primitives
  32 
  33         These are independent of the other SDL routines.
  34 */
  36 #include "SDL_main.h"
  37 #include "SDL_types.h"
  39 #include "begin_code.h"
  40 /* Set up for C function definitions, even when using C++ */
  41 #ifdef __cplusplus
  42 extern "C" {
  43 #endif
  45 /* Synchronization functions which can time out return this value
  46    if they time out.
  47 */
  48 #define SDL_MUTEX_TIMEDOUT      1
  50 /* This is the timeout value which corresponds to never time out */
  51 #define SDL_MUTEX_MAXWAIT       (~(Uint32)0)
  54 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
  55 /* Mutex functions                                               */
  56 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
  58 /* The SDL mutex structure, defined in SDL_mutex.c */
  59 struct SDL_mutex;
  60 typedef struct SDL_mutex SDL_mutex;
  62 /* Create a mutex, initialized unlocked */
  63 extern DECLSPEC SDL_mutex * SDL_CreateMutex(void);
  65 /* Lock the mutex  (Returns 0, or -1 on error) */
  66 #define SDL_LockMutex(m)        SDL_mutexP(m)
     /* [<][>][^][v][top][bottom][index][help] */
  67 extern DECLSPEC int SDL_mutexP(SDL_mutex *mutex);
  69 /* Unlock the mutex  (Returns 0, or -1 on error) */
  70 #define SDL_UnlockMutex(m)      SDL_mutexV(m)
     /* [<][>][^][v][top][bottom][index][help] */
  71 extern DECLSPEC int SDL_mutexV(SDL_mutex *mutex);
  73 /* Destroy a mutex */
  74 extern DECLSPEC void SDL_DestroyMutex(SDL_mutex *mutex);
  77 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
  78 /* Semaphore functions                                           */
  79 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
  81 /* The SDL semaphore structure, defined in SDL_sem.c */
  82 struct SDL_semaphore;
  83 typedef struct SDL_semaphore SDL_sem;
  85 /* Create a semaphore, initialized with value, returns NULL on failure. */
  86 extern DECLSPEC SDL_sem * SDL_CreateSemaphore(Uint32 initial_value);
  88 /* Destroy a semaphore */
  89 extern DECLSPEC void SDL_DestroySemaphore(SDL_sem *sem);
  91 /* This function suspends the calling thread until the semaphore pointed 
  92  * to by sem has a positive count. It then atomically decreases the semaphore
  93  * count.
  94  */
  95 extern DECLSPEC int SDL_SemWait(SDL_sem *sem);
  97 /* Non-blocking variant of SDL_SemWait(), returns 0 if the wait succeeds,
  98    SDL_MUTEX_TIMEDOUT if the wait would block, and -1 on error.
  99 */
 100 extern DECLSPEC int SDL_SemTryWait(SDL_sem *sem);
 102 /* Variant of SDL_SemWait() with a timeout in milliseconds, returns 0 if
 103    the wait succeeds, SDL_MUTEX_TIMEDOUT if the wait does not succeed in
 104    the allotted time, and -1 on error.
 105    On some platforms this function is implemented by looping with a delay
 106    of 1 ms, and so should be avoided if possible.
 107 */
 108 extern DECLSPEC int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 ms);
 110 /* Atomically increases the semaphore's count (not blocking), returns 0,
 111    or -1 on error.
 112  */
 113 extern DECLSPEC int SDL_SemPost(SDL_sem *sem);
 115 /* Returns the current count of the semaphore */
 116 extern DECLSPEC Uint32 SDL_SemValue(SDL_sem *sem);
 119 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
 120 /* Condition variable functions                                  */
 121 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
 123 /* The SDL condition variable structure, defined in SDL_cond.c */
 124 struct SDL_cond;
 125 typedef struct SDL_cond SDL_cond;
 127 /* Create a condition variable */
 128 extern DECLSPEC SDL_cond * SDL_CreateCond(void);
 130 /* Destroy a condition variable */
 131 extern DECLSPEC void SDL_DestroyCond(SDL_cond *cond);
 133 /* Restart one of the threads that are waiting on the condition variable,
 134    returns 0 or -1 on error.
 135  */
 136 extern DECLSPEC int SDL_CondSignal(SDL_cond *cond);
 138 /* Restart all threads that are waiting on the condition variable,
 139    returns 0 or -1 on error.
 140  */
 141 extern DECLSPEC int SDL_CondBroadcast(SDL_cond *cond);
 143 /* Wait on the condition variable, unlocking the provided mutex.
 144    The mutex must be locked before entering this function!
 145    Returns 0 when it is signaled, or -1 on error.
 146  */
 147 extern DECLSPEC int SDL_CondWait(SDL_cond *cond, SDL_mutex *mut);
 149 /* Waits for at most 'ms' milliseconds, and returns 0 if the condition
 150    variable is signaled, SDL_MUTEX_TIMEDOUT if the condition is not
 151    signaled in the allotted time, and -1 on error.
 152    On some platforms this function is implemented by looping with a delay
 153    of 1 ms, and so should be avoided if possible.
 154 */
 155 extern DECLSPEC int SDL_CondWaitTimeout(SDL_cond *cond, SDL_mutex *mutex, Uint32 ms);
 157 /* Ends C function definitions when using C++ */
 158 #ifdef __cplusplus
 159 }
 160 #endif
 161 #include "close_code.h"
 163 #endif /* _SDL_mutex_h */