forked from mirror/sdl
You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
252 lines
6.5 KiB
C
252 lines
6.5 KiB
C
/*
|
|
Simple DirectMedia Layer
|
|
Copyright (C) 1997-2020 Sam Lantinga <slouken@libsdl.org>
|
|
|
|
This software is provided 'as-is', without any express or implied
|
|
warranty. In no event will the authors be held liable for any damages
|
|
arising from the use of this software.
|
|
|
|
Permission is granted to anyone to use this software for any purpose,
|
|
including commercial applications, and to alter it and redistribute it
|
|
freely, subject to the following restrictions:
|
|
|
|
1. The origin of this software must not be misrepresented; you must not
|
|
claim that you wrote the original software. If you use this software
|
|
in a product, an acknowledgment in the product documentation would be
|
|
appreciated but is not required.
|
|
2. Altered source versions must be plainly marked as such, and must not be
|
|
misrepresented as being the original software.
|
|
3. This notice may not be removed or altered from any source distribution.
|
|
*/
|
|
|
|
#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
|
|
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_sysmutex.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_mutexP(m) SDL_LockMutex(m)
|
|
extern DECLSPEC int SDLCALL SDL_LockMutex(SDL_mutex * mutex);
|
|
|
|
/**
|
|
* Try to lock the mutex
|
|
*
|
|
* \return 0, SDL_MUTEX_TIMEDOUT, or -1 on error
|
|
*/
|
|
extern DECLSPEC int SDLCALL SDL_TryLockMutex(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_mutexV(m) SDL_UnlockMutex(m)
|
|
extern DECLSPEC int SDLCALL SDL_UnlockMutex(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_syssem.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_syscond.c */
|
|
struct SDL_cond;
|
|
typedef struct SDL_cond SDL_cond;
|
|
|
|
/**
|
|
* Create a condition variable.
|
|
*
|
|
* Typical use of condition variables:
|
|
*
|
|
* Thread A:
|
|
* SDL_LockMutex(lock);
|
|
* while ( ! condition ) {
|
|
* SDL_CondWait(cond, lock);
|
|
* }
|
|
* SDL_UnlockMutex(lock);
|
|
*
|
|
* Thread B:
|
|
* SDL_LockMutex(lock);
|
|
* ...
|
|
* condition = true;
|
|
* ...
|
|
* SDL_CondSignal(cond);
|
|
* SDL_UnlockMutex(lock);
|
|
*
|
|
* There is some discussion whether to signal the condition variable
|
|
* with the mutex locked or not. There is some potential performance
|
|
* benefit to unlocking first on some platforms, but there are some
|
|
* potential race conditions depending on how your code is structured.
|
|
*
|
|
* In general it's safer to signal the condition variable while the
|
|
* mutex is locked.
|
|
*/
|
|
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 * mutex);
|
|
|
|
/**
|
|
* 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
|
|
}
|
|
#endif
|
|
#include "close_code.h"
|
|
|
|
#endif /* SDL_mutex_h_ */
|
|
|
|
/* vi: set ts=4 sw=4 expandtab: */
|