X-Git-Url: https://git.ucc.asn.au/?p=ipdf%2Fcode.git;a=blobdiff_plain;f=contrib%2Finclude%2FSDL2%2FSDL_mutex.h;fp=contrib%2Finclude%2FSDL2%2FSDL_mutex.h;h=3e8b4dbed9a641e4cc096d79d02d094940192763;hp=0000000000000000000000000000000000000000;hb=26524b787a61cb6d8bb5f2f6925855768ac9471f;hpb=fdc6f69d40cf7e872218ec48493534cc3b85c852 diff --git a/contrib/include/SDL2/SDL_mutex.h b/contrib/include/SDL2/SDL_mutex.h new file mode 100644 index 0000000..3e8b4db --- /dev/null +++ b/contrib/include/SDL2/SDL_mutex.h @@ -0,0 +1,251 @@ +/* + Simple DirectMedia Layer + Copyright (C) 1997-2014 Sam Lantinga + + 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: */