text: /*
      SDL - Simple DirectMedia Layer
      Copyright (C) 1997-2012 Sam Lantinga
  
      This library is free software; you can redistribute it and/or
      modify it under the terms of the GNU Lesser General Public
      License as published by the Free Software Foundation; either
      version 2.1 of the License, or (at your option) any later version.
  
      This library is distributed in the hope that it will be useful,
      but WITHOUT ANY WARRANTY; without even the implied warranty of
      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      Lesser General Public License for more details.
  
      You should have received a copy of the GNU Lesser General Public
      License along with this library; if not, write to the Free Software
      Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  
      Sam Lantinga
      slouken@libsdl.org
  */
  
  #ifndef _SDL_mutex_h
  #define _SDL_mutex_h
  
  /** @file SDL_mutex.h
   *  Functions to provide thread synchronization primitives
   *
   *  @note These are independent of the other SDL routines.
   */
  
  #include "SDL_stdinc.h"
  #include "SDL_error.h"
  
  #include "begin_code.h"
  /* Set up for C function definitions, even when using C++ */
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /** Synchronization functions which can time out return this value
   *  if they time out.
   */
  #define SDL_MUTEX_TIMEDOUT	1
  
  /** This is the timeout value which corresponds to never time out */
  #define SDL_MUTEX_MAXWAIT	(~(Uint32)0)
  
  
  /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
  /** @name Mutex functions                                        */ /*@{*/
  /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
  
  /** The SDL mutex structure, defined in SDL_mutex.c */
  struct SDL_mutex;
  typedef struct SDL_mutex SDL_mutex;
  
  /** Create a mutex, initialized unlocked */
  extern DECLSPEC SDL_mutex * SDLCALL SDL_CreateMutex(void);
  
  #define SDL_LockMutex(m)	SDL_mutexP(m)
  /** Lock the mutex
   *  @return 0, or -1 on error
   */
  extern DECLSPEC int SDLCALL SDL_mutexP(SDL_mutex *mutex);
  
  #define SDL_UnlockMutex(m)	SDL_mutexV(m)
  /** Unlock the mutex
   *  @return 0, or -1 on error
   *
   *  It is an error to unlock a mutex that has not been locked by
   *  the current thread, and doing so results in undefined behavior.
   */
  extern DECLSPEC int SDLCALL SDL_mutexV(SDL_mutex *mutex);
  
  /** Destroy a mutex */
  extern DECLSPEC void SDLCALL SDL_DestroyMutex(SDL_mutex *mutex);
  
  /*@}*/
  
  /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
  /** @name Semaphore functions                                    */ /*@{*/
  /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
  
  /** The SDL semaphore structure, defined in SDL_sem.c */
  struct SDL_semaphore;
  typedef struct SDL_semaphore SDL_sem;
  
  /** Create a semaphore, initialized with value, returns NULL on failure. */
  extern DECLSPEC SDL_sem * SDLCALL SDL_CreateSemaphore(Uint32 initial_value);
  
  /** Destroy a semaphore */
  extern DECLSPEC void SDLCALL SDL_DestroySemaphore(SDL_sem *sem);
  
  /**
   * This function suspends the calling thread until the semaphore pointed 
   * to by sem has a positive count. It then atomically decreases the semaphore
   * count.
   */
  extern DECLSPEC int SDLCALL SDL_SemWait(SDL_sem *sem);
  
  /** Non-blocking variant of SDL_SemWait().
   *  @return 0 if the wait succeeds,
   *  SDL_MUTEX_TIMEDOUT if the wait would block, and -1 on error.
   */
  extern DECLSPEC int SDLCALL SDL_SemTryWait(SDL_sem *sem);
  
  /** Variant of SDL_SemWait() with a timeout in milliseconds, returns 0 if
   *  the wait succeeds, SDL_MUTEX_TIMEDOUT if the wait does not succeed in
   *  the allotted time, and -1 on error.
   *
   *  On some platforms this function is implemented by looping with a delay
   *  of 1 ms, and so should be avoided if possible.
   */
  extern DECLSPEC int SDLCALL SDL_SemWaitTimeout(SDL_sem *sem, Uint32 ms);
  
  /** Atomically increases the semaphore's count (not blocking).
   *  @return 0, or -1 on error.
   */
  extern DECLSPEC int SDLCALL SDL_SemPost(SDL_sem *sem);
  
  /** Returns the current count of the semaphore */
  extern DECLSPEC Uint32 SDLCALL SDL_SemValue(SDL_sem *sem);
  
  /*@}*/
  
  /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
  /** @name Condition_variable_functions                           */ /*@{*/
  /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
  
  /*@{*/
  /** The SDL condition variable structure, defined in SDL_cond.c */
  struct SDL_cond;
  typedef struct SDL_cond SDL_cond;
  /*@}*/
  
  /** Create a condition variable */
  extern DECLSPEC SDL_cond * SDLCALL SDL_CreateCond(void);
  
  /** Destroy a condition variable */
  extern DECLSPEC void SDLCALL SDL_DestroyCond(SDL_cond *cond);
  
  /** Restart one of the threads that are waiting on the condition variable,
   *  @return 0 or -1 on error.
   */
  extern DECLSPEC int SDLCALL SDL_CondSignal(SDL_cond *cond);
  
  /** Restart all threads that are waiting on the condition variable,
   *  @return 0 or -1 on error.
   */
  extern DECLSPEC int SDLCALL SDL_CondBroadcast(SDL_cond *cond);
  
  /** Wait on the condition variable, unlocking the provided mutex.
   *  The mutex must be locked before entering this function!
   *  The mutex is re-locked once the condition variable is signaled.
   *  @return 0 when it is signaled, or -1 on error.
   */
  extern DECLSPEC int SDLCALL SDL_CondWait(SDL_cond *cond, SDL_mutex *mut);
  
  /** Waits for at most 'ms' milliseconds, and returns 0 if the condition
   *  variable is signaled, SDL_MUTEX_TIMEDOUT if the condition is not
   *  signaled in the allotted time, and -1 on error.
   *  On some platforms this function is implemented by looping with a delay
   *  of 1 ms, and so should be avoided if possible.
   */
  extern DECLSPEC int SDLCALL SDL_CondWaitTimeout(SDL_cond *cond, SDL_mutex *mutex, Uint32 ms);
  
  /*@}*/
  
  /* Ends C function definitions when using C++ */
  #ifdef __cplusplus
  }
  #endif
  #include "close_code.h"
  
  #endif /* _SDL_mutex_h */
  
  