mirror of https://github.com/encounter/SDL.git
465 lines
17 KiB
C
465 lines
17 KiB
C
/*
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Simple DirectMedia Layer
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Copyright (C) 1997-2023 Sam Lantinga <slouken@libsdl.org>
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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*/
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#ifndef SDL_thread_h_
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#define SDL_thread_h_
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/**
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* \file SDL_thread.h
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*
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* Header for the SDL thread management routines.
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*/
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#include "SDL_stdinc.h"
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#include "SDL_error.h"
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/* Thread synchronization primitives */
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#include "SDL_atomic.h"
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#include "SDL_mutex.h"
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#if defined(__WIN32__) || defined(__GDK__)
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#include <process.h> /* _beginthreadex() and _endthreadex() */
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#endif
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#if defined(__OS2__) /* for _beginthread() and _endthread() */
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#ifndef __EMX__
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#include <process.h>
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#else
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#include <stdlib.h>
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#endif
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#endif
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#include "begin_code.h"
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/* Set up for C function definitions, even when using C++ */
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* The SDL thread structure, defined in SDL_thread.c */
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struct SDL_Thread;
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typedef struct SDL_Thread SDL_Thread;
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/* The SDL thread ID */
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typedef unsigned long SDL_threadID;
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/* Thread local storage ID, 0 is the invalid ID */
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typedef unsigned int SDL_TLSID;
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/**
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* The SDL thread priority.
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*
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* SDL will make system changes as necessary in order to apply the thread priority.
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* Code which attempts to control thread state related to priority should be aware
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* that calling SDL_SetThreadPriority may alter such state.
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* SDL_HINT_THREAD_PRIORITY_POLICY can be used to control aspects of this behavior.
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*
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* \note On many systems you require special privileges to set high or time critical priority.
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*/
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typedef enum {
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SDL_THREAD_PRIORITY_LOW,
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SDL_THREAD_PRIORITY_NORMAL,
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SDL_THREAD_PRIORITY_HIGH,
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SDL_THREAD_PRIORITY_TIME_CRITICAL
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} SDL_ThreadPriority;
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/**
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* The function passed to SDL_CreateThread().
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*
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* \param data what was passed as `data` to SDL_CreateThread()
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* \returns a value that can be reported through SDL_WaitThread().
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*/
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typedef int (SDLCALL * SDL_ThreadFunction) (void *data);
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#if defined(__WIN32__) || defined(__GDK__)
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/**
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* \file SDL_thread.h
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*
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* We compile SDL into a DLL. This means, that it's the DLL which
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* creates a new thread for the calling process with the SDL_CreateThread()
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* API. There is a problem with this, that only the RTL of the SDL2.DLL will
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* be initialized for those threads, and not the RTL of the calling
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* application!
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*
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* To solve this, we make a little hack here.
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*
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* We'll always use the caller's _beginthread() and _endthread() APIs to
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* start a new thread. This way, if it's the SDL2.DLL which uses this API,
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* then the RTL of SDL2.DLL will be used to create the new thread, and if it's
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* the application, then the RTL of the application will be used.
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*
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* So, in short:
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* Always use the _beginthread() and _endthread() of the calling runtime
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* library!
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*/
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#define SDL_PASSED_BEGINTHREAD_ENDTHREAD
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typedef uintptr_t (__cdecl * pfnSDL_CurrentBeginThread)
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(void *, unsigned, unsigned (__stdcall *func)(void *),
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void * /*arg*/, unsigned, unsigned * /* threadID */);
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typedef void (__cdecl * pfnSDL_CurrentEndThread) (unsigned code);
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#ifndef SDL_beginthread
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#define SDL_beginthread _beginthreadex
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#endif
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#ifndef SDL_endthread
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#define SDL_endthread _endthreadex
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#endif
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extern DECLSPEC SDL_Thread *SDLCALL
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SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
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pfnSDL_CurrentBeginThread pfnBeginThread,
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pfnSDL_CurrentEndThread pfnEndThread);
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extern DECLSPEC SDL_Thread *SDLCALL
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SDL_CreateThreadWithStackSize(SDL_ThreadFunction fn,
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const char *name, const size_t stacksize, void *data,
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pfnSDL_CurrentBeginThread pfnBeginThread,
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pfnSDL_CurrentEndThread pfnEndThread);
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#if defined(SDL_CreateThread) && SDL_DYNAMIC_API
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#undef SDL_CreateThread
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#define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
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#undef SDL_CreateThreadWithStackSize
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#define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize_REAL(fn, name, stacksize, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
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#else
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#define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
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#define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize(fn, name, stacksize, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
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#endif
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#elif defined(__OS2__)
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/*
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* just like the windows case above: We compile SDL2
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* into a dll with Watcom's runtime statically linked.
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*/
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#define SDL_PASSED_BEGINTHREAD_ENDTHREAD
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typedef int (*pfnSDL_CurrentBeginThread)(void (*func)(void *), void *, unsigned, void * /*arg*/);
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typedef void (*pfnSDL_CurrentEndThread)(void);
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#ifndef SDL_beginthread
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#define SDL_beginthread _beginthread
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#endif
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#ifndef SDL_endthread
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#define SDL_endthread _endthread
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#endif
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extern DECLSPEC SDL_Thread *SDLCALL
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SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
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pfnSDL_CurrentBeginThread pfnBeginThread,
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pfnSDL_CurrentEndThread pfnEndThread);
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extern DECLSPEC SDL_Thread *SDLCALL
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SDL_CreateThreadWithStackSize(SDL_ThreadFunction fn, const char *name, const size_t stacksize, void *data,
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pfnSDL_CurrentBeginThread pfnBeginThread,
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pfnSDL_CurrentEndThread pfnEndThread);
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#if defined(SDL_CreateThread) && SDL_DYNAMIC_API
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#undef SDL_CreateThread
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#define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
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#undef SDL_CreateThreadWithStackSize
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#define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize_REAL(fn, name, stacksize, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
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#else
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#define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
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#define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize(fn, name, stacksize, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
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#endif
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#else
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/**
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* Create a new thread with a default stack size.
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*
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* This is equivalent to calling:
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*
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* ```c
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* SDL_CreateThreadWithStackSize(fn, name, 0, data);
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* ```
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*
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* \param fn the SDL_ThreadFunction function to call in the new thread
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* \param name the name of the thread
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* \param data a pointer that is passed to `fn`
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* \returns an opaque pointer to the new thread object on success, NULL if the
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* new thread could not be created; call SDL_GetError() for more
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* information.
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*
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* \since This function is available since SDL 2.0.0.
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*
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* \sa SDL_CreateThreadWithStackSize
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* \sa SDL_WaitThread
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*/
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extern DECLSPEC SDL_Thread *SDLCALL
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SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data);
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/**
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* Create a new thread with a specific stack size.
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*
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* SDL makes an attempt to report `name` to the system, so that debuggers can
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* display it. Not all platforms support this.
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*
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* Thread naming is a little complicated: Most systems have very small limits
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* for the string length (Haiku has 32 bytes, Linux currently has 16, Visual
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* C++ 6.0 has _nine_!), and possibly other arbitrary rules. You'll have to
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* see what happens with your system's debugger. The name should be UTF-8 (but
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* using the naming limits of C identifiers is a better bet). There are no
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* requirements for thread naming conventions, so long as the string is
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* null-terminated UTF-8, but these guidelines are helpful in choosing a name:
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*
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* https://stackoverflow.com/questions/149932/naming-conventions-for-threads
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*
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* If a system imposes requirements, SDL will try to munge the string for it
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* (truncate, etc), but the original string contents will be available from
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* SDL_GetThreadName().
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*
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* The size (in bytes) of the new stack can be specified. Zero means "use the
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* system default" which might be wildly different between platforms. x86
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* Linux generally defaults to eight megabytes, an embedded device might be a
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* few kilobytes instead. You generally need to specify a stack that is a
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* multiple of the system's page size (in many cases, this is 4 kilobytes, but
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* check your system documentation).
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*
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* In SDL 2.1, stack size will be folded into the original SDL_CreateThread
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* function, but for backwards compatibility, this is currently a separate
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* function.
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*
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* \param fn the SDL_ThreadFunction function to call in the new thread
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* \param name the name of the thread
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* \param stacksize the size, in bytes, to allocate for the new thread stack.
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* \param data a pointer that is passed to `fn`
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* \returns an opaque pointer to the new thread object on success, NULL if the
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* new thread could not be created; call SDL_GetError() for more
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* information.
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*
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* \since This function is available since SDL 2.0.9.
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*
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* \sa SDL_WaitThread
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*/
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extern DECLSPEC SDL_Thread *SDLCALL
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SDL_CreateThreadWithStackSize(SDL_ThreadFunction fn, const char *name, const size_t stacksize, void *data);
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#endif
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/**
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* Get the thread name as it was specified in SDL_CreateThread().
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*
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* This is internal memory, not to be freed by the caller, and remains valid
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* until the specified thread is cleaned up by SDL_WaitThread().
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*
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* \param thread the thread to query
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* \returns a pointer to a UTF-8 string that names the specified thread, or
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* NULL if it doesn't have a name.
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*
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* \since This function is available since SDL 2.0.0.
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*
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* \sa SDL_CreateThread
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*/
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extern DECLSPEC const char *SDLCALL SDL_GetThreadName(SDL_Thread *thread);
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/**
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* Get the thread identifier for the current thread.
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*
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* This thread identifier is as reported by the underlying operating system.
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* If SDL is running on a platform that does not support threads the return
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* value will always be zero.
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*
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* This function also returns a valid thread ID when called from the main
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* thread.
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*
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* \returns the ID of the current thread.
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*
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* \since This function is available since SDL 2.0.0.
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*
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* \sa SDL_GetThreadID
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*/
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extern DECLSPEC SDL_threadID SDLCALL SDL_ThreadID(void);
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/**
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* Get the thread identifier for the specified thread.
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*
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* This thread identifier is as reported by the underlying operating system.
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* If SDL is running on a platform that does not support threads the return
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* value will always be zero.
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*
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* \param thread the thread to query
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* \returns the ID of the specified thread, or the ID of the current thread if
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* `thread` is NULL.
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*
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* \since This function is available since SDL 2.0.0.
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*
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* \sa SDL_ThreadID
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*/
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extern DECLSPEC SDL_threadID SDLCALL SDL_GetThreadID(SDL_Thread * thread);
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/**
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* Set the priority for the current thread.
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*
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* Note that some platforms will not let you alter the priority (or at least,
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* promote the thread to a higher priority) at all, and some require you to be
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* an administrator account. Be prepared for this to fail.
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*
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* \param priority the SDL_ThreadPriority to set
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* \returns 0 on success or a negative error code on failure; call
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* SDL_GetError() for more information.
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*
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* \since This function is available since SDL 2.0.0.
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*/
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extern DECLSPEC int SDLCALL SDL_SetThreadPriority(SDL_ThreadPriority priority);
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/**
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* Wait for a thread to finish.
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*
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* Threads that haven't been detached will remain (as a "zombie") until this
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* function cleans them up. Not doing so is a resource leak.
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*
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* Once a thread has been cleaned up through this function, the SDL_Thread
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* that references it becomes invalid and should not be referenced again. As
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* such, only one thread may call SDL_WaitThread() on another.
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*
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* The return code for the thread function is placed in the area pointed to by
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* `status`, if `status` is not NULL.
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*
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* You may not wait on a thread that has been used in a call to
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* SDL_DetachThread(). Use either that function or this one, but not both, or
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* behavior is undefined.
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*
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* It is safe to pass a NULL thread to this function; it is a no-op.
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*
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* Note that the thread pointer is freed by this function and is not valid
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* afterward.
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*
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* \param thread the SDL_Thread pointer that was returned from the
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* SDL_CreateThread() call that started this thread
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* \param status pointer to an integer that will receive the value returned
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* from the thread function by its 'return', or NULL to not
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* receive such value back.
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*
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* \since This function is available since SDL 2.0.0.
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*
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* \sa SDL_CreateThread
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* \sa SDL_DetachThread
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*/
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extern DECLSPEC void SDLCALL SDL_WaitThread(SDL_Thread * thread, int *status);
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/**
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* Let a thread clean up on exit without intervention.
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*
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* A thread may be "detached" to signify that it should not remain until
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* another thread has called SDL_WaitThread() on it. Detaching a thread is
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* useful for long-running threads that nothing needs to synchronize with or
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* further manage. When a detached thread is done, it simply goes away.
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*
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* There is no way to recover the return code of a detached thread. If you
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* need this, don't detach the thread and instead use SDL_WaitThread().
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*
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* Once a thread is detached, you should usually assume the SDL_Thread isn't
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* safe to reference again, as it will become invalid immediately upon the
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* detached thread's exit, instead of remaining until someone has called
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* SDL_WaitThread() to finally clean it up. As such, don't detach the same
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* thread more than once.
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*
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* If a thread has already exited when passed to SDL_DetachThread(), it will
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* stop waiting for a call to SDL_WaitThread() and clean up immediately. It is
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* not safe to detach a thread that might be used with SDL_WaitThread().
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*
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* You may not call SDL_WaitThread() on a thread that has been detached. Use
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* either that function or this one, but not both, or behavior is undefined.
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*
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* It is safe to pass NULL to this function; it is a no-op.
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*
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* \param thread the SDL_Thread pointer that was returned from the
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* SDL_CreateThread() call that started this thread
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*
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* \since This function is available since SDL 2.0.2.
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*
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* \sa SDL_CreateThread
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* \sa SDL_WaitThread
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*/
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extern DECLSPEC void SDLCALL SDL_DetachThread(SDL_Thread * thread);
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/**
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* Create a piece of thread-local storage.
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*
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* This creates an identifier that is globally visible to all threads but
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* refers to data that is thread-specific.
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*
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* \returns the newly created thread local storage identifier or 0 on error.
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*
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* \since This function is available since SDL 2.0.0.
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*
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* \sa SDL_TLSGet
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* \sa SDL_TLSSet
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*/
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extern DECLSPEC SDL_TLSID SDLCALL SDL_TLSCreate(void);
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/**
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* Get the current thread's value associated with a thread local storage ID.
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*
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* \param id the thread local storage ID
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* \returns the value associated with the ID for the current thread or NULL if
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* no value has been set; call SDL_GetError() for more information.
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*
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* \since This function is available since SDL 2.0.0.
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*
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* \sa SDL_TLSCreate
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* \sa SDL_TLSSet
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*/
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extern DECLSPEC void * SDLCALL SDL_TLSGet(SDL_TLSID id);
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/**
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* Set the current thread's value associated with a thread local storage ID.
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*
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* The function prototype for `destructor` is:
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*
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* ```c
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* void destructor(void *value)
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* ```
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*
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* where its parameter `value` is what was passed as `value` to SDL_TLSSet().
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*
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* \param id the thread local storage ID
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* \param value the value to associate with the ID for the current thread
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* \param destructor a function called when the thread exits, to free the
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* value
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* \returns 0 on success or a negative error code on failure; call
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* SDL_GetError() for more information.
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*
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* \since This function is available since SDL 2.0.0.
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*
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* \sa SDL_TLSCreate
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* \sa SDL_TLSGet
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*/
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extern DECLSPEC int SDLCALL SDL_TLSSet(SDL_TLSID id, const void *value, void (SDLCALL *destructor)(void*));
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/**
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* Cleanup all TLS data for this thread.
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*
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* \since This function is available since SDL 2.0.16.
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*/
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extern DECLSPEC void SDLCALL SDL_TLSCleanup(void);
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/* Ends C function definitions when using C++ */
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#ifdef __cplusplus
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}
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#endif
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#include "close_code.h"
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#endif /* SDL_thread_h_ */
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/* vi: set ts=4 sw=4 expandtab: */
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