/*

    SDL - Simple DirectMedia Layer

    Copyright (C) 1997-2009 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.

 */

#include "SDL_stdinc.h"

#include "SDL_error.h"

#include "begin_code.h"

/* Set up for C function definitions, even when using C++ */

#ifdef __cplusplus

/* *INDENT-OFF* */

extern "C" {

/* *INDENT-ON* */

#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);

/**

 *  Lock the mutex.

 *  

 *  \return 0, or -1 on error.

 */

#define SDL_LockMutex(m)	SDL_mutexP(m)

extern DECLSPEC int SDLCALL SDL_mutexP(SDL_mutex * mutex);

/**

 *  Unlock the mutex.

 *  

 *  \return 0, or -1 on error.

 *  

 *  \warning It is an error to unlock a mutex that has not been locked by

 *           the current thread, and doing so results in undefined behavior.

 */

#define SDL_UnlockMutex(m)	SDL_mutexV(m)

extern DECLSPEC int SDLCALL SDL_mutexV(SDL_mutex * mutex);

/** 

 *  Destroy a mutex.

 */

extern DECLSPEC void SDLCALL SDL_DestroyMutex(SDL_mutex * mutex);

/*@}*//*Mutex functions*/

/**

 *  \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 \c 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.

 *  

 *  \return 0 if the wait succeeds, ::SDL_MUTEX_TIMEDOUT if the wait does not 

 *          succeed in the allotted time, and -1 on error.

 *  

 *  \warning 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);

/*@}*//*Semaphore functions*/

/**

 *  \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.

 *  

 *  \warning 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 \c 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.

 *

 *  \warning 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);

/*@}*//*Condition variable functions*/

/* Ends C function definitions when using C++ */

#ifdef __cplusplus

/* *INDENT-OFF* */

}

/* *INDENT-ON* */

#endif

#include "close_code.h"

#endif /* _SDL_mutex_h */

/* vi: set ts=4 sw=4 expandtab: */