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SDL_mutex.h
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SDL_mutex.h
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/*
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 */