src/thread/SDL_thread.c - external/github.com/libsdl-org/SDL - Git at Google

 /*
   Simple DirectMedia Layer
   Copyright (C) 1997-2024 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.
 */
 #include "SDL_internal.h"

 /* System independent thread management routines for SDL */

 #include "SDL_thread_c.h"
 #include "SDL_systhread.h"
 #include "../SDL_error_c.h"

 SDL_TLSID SDL_CreateTLS(void)
 {
     static SDL_AtomicInt SDL_tls_id;
     return (SDL_TLSID)(SDL_AtomicIncRef(&SDL_tls_id) + 1);
 }

 void *SDL_GetTLS(SDL_TLSID id)
 {
     SDL_TLSData *storage;

     storage = SDL_SYS_GetTLSData();
     if (!storage || id == 0 || id > storage->limit) {
         return NULL;
     }
     return storage->array[id - 1].data;
 }

 int SDL_SetTLS(SDL_TLSID id, const void *value, void(SDLCALL *destructor)(void *))
 {
     SDL_TLSData *storage;

     if (id == 0) {
         return SDL_InvalidParamError("id");
     }

     storage = SDL_SYS_GetTLSData();
     if (!storage || (id > storage->limit)) {
         unsigned int i, oldlimit, newlimit;
         SDL_TLSData *new_storage;

         oldlimit = storage ? storage->limit : 0;
         newlimit = (id + TLS_ALLOC_CHUNKSIZE);
         new_storage = (SDL_TLSData *)SDL_realloc(storage, sizeof(*storage) + (newlimit - 1) * sizeof(storage->array[0]));
         if (!new_storage) {
             SDL_OutOfMemory();
             return -1;
         }
         storage = new_storage;
         storage->limit = newlimit;
         for (i = oldlimit; i < newlimit; ++i) {
             storage->array[i].data = NULL;
             storage->array[i].destructor = NULL;
         }
         if (SDL_SYS_SetTLSData(storage) != 0) {
             return -1;
         }
     }

     storage->array[id - 1].data = SDL_const_cast(void *, value);
     storage->array[id - 1].destructor = destructor;
     return 0;
 }

 void SDL_CleanupTLS(void)
 {
     SDL_TLSData *storage;

     storage = SDL_SYS_GetTLSData();
     if (storage) {
         unsigned int i;
         for (i = 0; i < storage->limit; ++i) {
             if (storage->array[i].destructor) {
                 storage->array[i].destructor(storage->array[i].data);
             }
         }
         SDL_SYS_SetTLSData(NULL);
         SDL_free(storage);
     }
 }

 /* This is a generic implementation of thread-local storage which doesn't
    require additional OS support.

    It is not especially efficient and doesn't clean up thread-local storage
    as threads exit.  If there is a real OS that doesn't support thread-local
    storage this implementation should be improved to be production quality.
 */

 typedef struct SDL_TLSEntry
 {
     SDL_ThreadID thread;
     SDL_TLSData *storage;
     struct SDL_TLSEntry *next;
 } SDL_TLSEntry;

 static SDL_Mutex *SDL_generic_TLS_mutex;
 static SDL_TLSEntry *SDL_generic_TLS;

 SDL_TLSData *SDL_Generic_GetTLSData(void)
 {
     SDL_ThreadID thread = SDL_GetCurrentThreadID();
     SDL_TLSEntry *entry;
     SDL_TLSData *storage = NULL;

 #ifndef SDL_THREADS_DISABLED
     if (!SDL_generic_TLS_mutex) {
         static SDL_SpinLock tls_lock;
         SDL_LockSpinlock(&tls_lock);
         if (!SDL_generic_TLS_mutex) {
             SDL_Mutex *mutex = SDL_CreateMutex();
             SDL_MemoryBarrierRelease();
             SDL_generic_TLS_mutex = mutex;
             if (!SDL_generic_TLS_mutex) {
                 SDL_UnlockSpinlock(&tls_lock);
                 return NULL;
             }
         }
         SDL_UnlockSpinlock(&tls_lock);
     }
     SDL_MemoryBarrierAcquire();
     SDL_LockMutex(SDL_generic_TLS_mutex);
 #endif /* SDL_THREADS_DISABLED */

     for (entry = SDL_generic_TLS; entry; entry = entry->next) {
         if (entry->thread == thread) {
             storage = entry->storage;
             break;
         }
     }
 #ifndef SDL_THREADS_DISABLED
     SDL_UnlockMutex(SDL_generic_TLS_mutex);
 #endif

     return storage;
 }

 int SDL_Generic_SetTLSData(SDL_TLSData *data)
 {
     SDL_ThreadID thread = SDL_GetCurrentThreadID();
     SDL_TLSEntry *prev, *entry;

     /* SDL_Generic_GetTLSData() is always called first, so we can assume SDL_generic_TLS_mutex */
     SDL_LockMutex(SDL_generic_TLS_mutex);
     prev = NULL;
     for (entry = SDL_generic_TLS; entry; entry = entry->next) {
         if (entry->thread == thread) {
             if (data) {
                 entry->storage = data;
             } else {
                 if (prev) {
                     prev->next = entry->next;
                 } else {
                     SDL_generic_TLS = entry->next;
                 }
                 SDL_free(entry);
             }
             break;
         }
         prev = entry;
     }
     if (!entry) {
         entry = (SDL_TLSEntry *)SDL_malloc(sizeof(*entry));
         if (entry) {
             entry->thread = thread;
             entry->storage = data;
             entry->next = SDL_generic_TLS;
             SDL_generic_TLS = entry;
         }
     }
     SDL_UnlockMutex(SDL_generic_TLS_mutex);

     return entry ? 0 : -1;
 }

 /* Non-thread-safe global error variable */
 static SDL_error *SDL_GetStaticErrBuf(void)
 {
     static SDL_error SDL_global_error;
     static char SDL_global_error_str[128];
     SDL_global_error.str = SDL_global_error_str;
     SDL_global_error.len = sizeof(SDL_global_error_str);
     return &SDL_global_error;
 }

 #ifndef SDL_THREADS_DISABLED
 static void SDLCALL SDL_FreeErrBuf(void *data)
 {
     SDL_error *errbuf = (SDL_error *)data;

     if (errbuf->str) {
         errbuf->free_func(errbuf->str);
     }
     errbuf->free_func(errbuf);
 }
 #endif

 /* Routine to get the thread-specific error variable */
 SDL_error *SDL_GetErrBuf(SDL_bool create)
 {
 #ifdef SDL_THREADS_DISABLED
     return SDL_GetStaticErrBuf();
 #else
     static SDL_SpinLock tls_lock;
     static SDL_bool tls_being_created;
     static SDL_TLSID tls_errbuf;
     const SDL_error *ALLOCATION_IN_PROGRESS = (SDL_error *)-1;
     SDL_error *errbuf;

     if (!tls_errbuf && !create) {
         return NULL;
     }

     /* tls_being_created is there simply to prevent recursion if SDL_CreateTLS() fails.
        It also means it's possible for another thread to also use SDL_global_errbuf,
        but that's very unlikely and hopefully won't cause issues.
      */
     if (!tls_errbuf && !tls_being_created) {
         SDL_LockSpinlock(&tls_lock);
         if (!tls_errbuf) {
             SDL_TLSID slot;
             tls_being_created = SDL_TRUE;
             slot = SDL_CreateTLS();
             tls_being_created = SDL_FALSE;
             SDL_MemoryBarrierRelease();
             tls_errbuf = slot;
         }
         SDL_UnlockSpinlock(&tls_lock);
     }
     if (!tls_errbuf) {
         return SDL_GetStaticErrBuf();
     }

     SDL_MemoryBarrierAcquire();
     errbuf = (SDL_error *)SDL_GetTLS(tls_errbuf);
     if (errbuf == ALLOCATION_IN_PROGRESS) {
         return SDL_GetStaticErrBuf();
     }
     if (!errbuf) {
         /* Get the original memory functions for this allocation because the lifetime
          * of the error buffer may span calls to SDL_SetMemoryFunctions() by the app
          */
         SDL_realloc_func realloc_func;
         SDL_free_func free_func;
         SDL_GetOriginalMemoryFunctions(NULL, NULL, &realloc_func, &free_func);

         /* Mark that we're in the middle of allocating our buffer */
         SDL_SetTLS(tls_errbuf, ALLOCATION_IN_PROGRESS, NULL);
         errbuf = (SDL_error *)realloc_func(NULL, sizeof(*errbuf));
         if (!errbuf) {
             SDL_SetTLS(tls_errbuf, NULL, NULL);
             return SDL_GetStaticErrBuf();
         }
         SDL_zerop(errbuf);
         errbuf->realloc_func = realloc_func;
         errbuf->free_func = free_func;
         SDL_SetTLS(tls_errbuf, errbuf, SDL_FreeErrBuf);
     }
     return errbuf;
 #endif /* SDL_THREADS_DISABLED */
 }

 void SDL_RunThread(SDL_Thread *thread)
 {
     void *userdata = thread->userdata;
     int(SDLCALL * userfunc)(void *) = thread->userfunc;

     int *statusloc = &thread->status;

     /* Perform any system-dependent setup - this function may not fail */
     SDL_SYS_SetupThread(thread->name);

     /* Get the thread id */
     thread->threadid = SDL_GetCurrentThreadID();

     /* Run the function */
     *statusloc = userfunc(userdata);

     /* Clean up thread-local storage */
     SDL_CleanupTLS();

     /* Mark us as ready to be joined (or detached) */
     if (!SDL_AtomicCompareAndSwap(&thread->state, SDL_THREAD_STATE_ALIVE, SDL_THREAD_STATE_ZOMBIE)) {
         /* Clean up if something already detached us. */
         if (SDL_AtomicCompareAndSwap(&thread->state, SDL_THREAD_STATE_DETACHED, SDL_THREAD_STATE_CLEANED)) {
             if (thread->name) {
                 SDL_free(thread->name);
             }
             SDL_free(thread);
         }
     }
 }

 #ifdef SDL_CreateThread
 #undef SDL_CreateThread
 #undef SDL_CreateThreadWithStackSize
 #endif
 #if SDL_DYNAMIC_API
 #define SDL_CreateThread              SDL_CreateThread_REAL
 #define SDL_CreateThreadWithStackSize SDL_CreateThreadWithStackSize_REAL
 #endif

 #ifdef SDL_PASSED_BEGINTHREAD_ENDTHREAD
 SDL_Thread *SDL_CreateThreadWithStackSize(int(SDLCALL *fn)(void *),
                               const char *name, const size_t stacksize, void *data,
                               pfnSDL_CurrentBeginThread pfnBeginThread,
                               pfnSDL_CurrentEndThread pfnEndThread)
 #else
 SDL_Thread *SDL_CreateThreadWithStackSize(int(SDLCALL *fn)(void *),
                               const char *name, const size_t stacksize, void *data)
 #endif
 {
     SDL_Thread *thread;
     int ret;

     /* Allocate memory for the thread info structure */
     thread = (SDL_Thread *)SDL_calloc(1, sizeof(*thread));
     if (!thread) {
         return NULL;
     }
     thread->status = -1;
     SDL_AtomicSet(&thread->state, SDL_THREAD_STATE_ALIVE);

     /* Set up the arguments for the thread */
     if (name) {
         thread->name = SDL_strdup(name);
         if (!thread->name) {
             SDL_free(thread);
             return NULL;
         }
     }

     thread->userfunc = fn;
     thread->userdata = data;
     thread->stacksize = stacksize;

     /* Create the thread and go! */
 #ifdef SDL_PASSED_BEGINTHREAD_ENDTHREAD
     ret = SDL_SYS_CreateThread(thread, pfnBeginThread, pfnEndThread);
 #else
     ret = SDL_SYS_CreateThread(thread);
 #endif
     if (ret < 0) {
         /* Oops, failed.  Gotta free everything */
         SDL_free(thread->name);
         SDL_free(thread);
         thread = NULL;
     }

     /* Everything is running now */
     return thread;
 }

 #ifdef SDL_PASSED_BEGINTHREAD_ENDTHREAD
 DECLSPEC SDL_Thread *SDLCALL SDL_CreateThread(int(SDLCALL *fn)(void *),
                  const char *name, void *data,
                  pfnSDL_CurrentBeginThread pfnBeginThread,
                  pfnSDL_CurrentEndThread pfnEndThread)
 #else
 DECLSPEC SDL_Thread *SDLCALL SDL_CreateThread(int(SDLCALL *fn)(void *),
                  const char *name, void *data)
 #endif
 {
 #ifdef SDL_PASSED_BEGINTHREAD_ENDTHREAD
     return SDL_CreateThreadWithStackSize(fn, name, 0, data, pfnBeginThread, pfnEndThread);
 #else
     return SDL_CreateThreadWithStackSize(fn, name, 0, data);
 #endif
 }

 SDL_Thread *SDL_CreateThreadInternal(int(SDLCALL *fn)(void *), const char *name,
                          const size_t stacksize, void *data)
 {
 #ifdef SDL_PASSED_BEGINTHREAD_ENDTHREAD
     return SDL_CreateThreadWithStackSize(fn, name, stacksize, data, NULL, NULL);
 #else
     return SDL_CreateThreadWithStackSize(fn, name, stacksize, data);
 #endif
 }

 SDL_ThreadID SDL_GetThreadID(SDL_Thread *thread)
 {
     SDL_ThreadID id;

     if (thread) {
         id = thread->threadid;
     } else {
         id = SDL_GetCurrentThreadID();
     }
     return id;
 }

 const char *SDL_GetThreadName(SDL_Thread *thread)
 {
     if (thread) {
         return thread->name;
     } else {
         return NULL;
     }
 }

 int SDL_SetThreadPriority(SDL_ThreadPriority priority)
 {
     return SDL_SYS_SetThreadPriority(priority);
 }

 void SDL_WaitThread(SDL_Thread *thread, int *status)
 {
     if (thread) {
         SDL_SYS_WaitThread(thread);
         if (status) {
             *status = thread->status;
         }
         if (thread->name) {
             SDL_free(thread->name);
         }
         SDL_free(thread);
     }
 }

 void SDL_DetachThread(SDL_Thread *thread)
 {
     if (!thread) {
         return;
     }

     /* Grab dibs if the state is alive+joinable. */
     if (SDL_AtomicCompareAndSwap(&thread->state, SDL_THREAD_STATE_ALIVE, SDL_THREAD_STATE_DETACHED)) {
         SDL_SYS_DetachThread(thread);
     } else {
         /* all other states are pretty final, see where we landed. */
         const int thread_state = SDL_AtomicGet(&thread->state);
         if ((thread_state == SDL_THREAD_STATE_DETACHED) || (thread_state == SDL_THREAD_STATE_CLEANED)) {
             return; /* already detached (you shouldn't call this twice!) */
         } else if (thread_state == SDL_THREAD_STATE_ZOMBIE) {
             SDL_WaitThread(thread, NULL); /* already done, clean it up. */
         } else {
             SDL_assert(0 && "Unexpected thread state");
         }
     }
 }

 int SDL_WaitSemaphore(SDL_Semaphore *sem)
 {
     return SDL_WaitSemaphoreTimeoutNS(sem, -1);
 }

 int SDL_TryWaitSemaphore(SDL_Semaphore *sem)
 {
     return SDL_WaitSemaphoreTimeoutNS(sem, 0);
 }

 int SDL_WaitSemaphoreTimeout(SDL_Semaphore *sem, Sint32 timeoutMS)
 {
     Sint64 timeoutNS;

     if (timeoutMS >= 0) {
         timeoutNS = SDL_MS_TO_NS(timeoutMS);
     } else {
         timeoutNS = -1;
     }
     return SDL_WaitSemaphoreTimeoutNS(sem, timeoutNS);
 }

 int SDL_WaitCondition(SDL_Condition *cond, SDL_Mutex *mutex)
 {
     return SDL_WaitConditionTimeoutNS(cond, mutex, -1);
 }

 int SDL_WaitConditionTimeout(SDL_Condition *cond, SDL_Mutex *mutex, Sint32 timeoutMS)
 {
     Sint64 timeoutNS;

     if (timeoutMS >= 0) {
         timeoutNS = SDL_MS_TO_NS(timeoutMS);
     } else {
         timeoutNS = -1;
     }
     return SDL_WaitConditionTimeoutNS(cond, mutex, timeoutNS);
 }
	/*
	Simple DirectMedia Layer
	Copyright (C) 1997-2024 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.
	*/
	#include "SDL_internal.h"

	/* System independent thread management routines for SDL */

	#include "SDL_thread_c.h"
	#include "SDL_systhread.h"
	#include "../SDL_error_c.h"

	SDL_TLSID SDL_CreateTLS(void)
	{
	static SDL_AtomicInt SDL_tls_id;
	return (SDL_TLSID)(SDL_AtomicIncRef(&SDL_tls_id) + 1);
	}

	void *SDL_GetTLS(SDL_TLSID id)
	{
	SDL_TLSData *storage;

	storage = SDL_SYS_GetTLSData();
	if (!storage \|\| id == 0 \|\| id > storage->limit) {
	return NULL;
	}
	return storage->array[id - 1].data;
	}

	int SDL_SetTLS(SDL_TLSID id, const void value, void(SDLCALL destructor)(void *))
	{
	SDL_TLSData *storage;

	if (id == 0) {
	return SDL_InvalidParamError("id");
	}

	storage = SDL_SYS_GetTLSData();
	if (!storage \|\| (id > storage->limit)) {
	unsigned int i, oldlimit, newlimit;
	SDL_TLSData *new_storage;

	oldlimit = storage ? storage->limit : 0;
	newlimit = (id + TLS_ALLOC_CHUNKSIZE);
	new_storage = (SDL_TLSData )SDL_realloc(storage, sizeof(storage) + (newlimit - 1) * sizeof(storage->array[0]));
	if (!new_storage) {
	SDL_OutOfMemory();
	return -1;
	}
	storage = new_storage;
	storage->limit = newlimit;
	for (i = oldlimit; i < newlimit; ++i) {
	storage->array[i].data = NULL;
	storage->array[i].destructor = NULL;
	}
	if (SDL_SYS_SetTLSData(storage) != 0) {
	return -1;
	}
	}

	storage->array[id - 1].data = SDL_const_cast(void *, value);
	storage->array[id - 1].destructor = destructor;
	return 0;
	}

	void SDL_CleanupTLS(void)
	{
	SDL_TLSData *storage;

	storage = SDL_SYS_GetTLSData();
	if (storage) {
	unsigned int i;
	for (i = 0; i < storage->limit; ++i) {
	if (storage->array[i].destructor) {
	storage->array[i].destructor(storage->array[i].data);
	}
	}
	SDL_SYS_SetTLSData(NULL);
	SDL_free(storage);
	}
	}

	/* This is a generic implementation of thread-local storage which doesn't
	require additional OS support.

	It is not especially efficient and doesn't clean up thread-local storage
	as threads exit. If there is a real OS that doesn't support thread-local
	storage this implementation should be improved to be production quality.
	*/

	typedef struct SDL_TLSEntry
	{
	SDL_ThreadID thread;
	SDL_TLSData *storage;
	struct SDL_TLSEntry *next;
	} SDL_TLSEntry;

	static SDL_Mutex *SDL_generic_TLS_mutex;
	static SDL_TLSEntry *SDL_generic_TLS;

	SDL_TLSData *SDL_Generic_GetTLSData(void)
	{
	SDL_ThreadID thread = SDL_GetCurrentThreadID();
	SDL_TLSEntry *entry;
	SDL_TLSData *storage = NULL;

	#ifndef SDL_THREADS_DISABLED
	if (!SDL_generic_TLS_mutex) {
	static SDL_SpinLock tls_lock;
	SDL_LockSpinlock(&tls_lock);
	if (!SDL_generic_TLS_mutex) {
	SDL_Mutex *mutex = SDL_CreateMutex();
	SDL_MemoryBarrierRelease();
	SDL_generic_TLS_mutex = mutex;
	if (!SDL_generic_TLS_mutex) {
	SDL_UnlockSpinlock(&tls_lock);
	return NULL;
	}
	}
	SDL_UnlockSpinlock(&tls_lock);
	}
	SDL_MemoryBarrierAcquire();
	SDL_LockMutex(SDL_generic_TLS_mutex);
	#endif /* SDL_THREADS_DISABLED */

	for (entry = SDL_generic_TLS; entry; entry = entry->next) {
	if (entry->thread == thread) {
	storage = entry->storage;
	break;
	}
	}
	#ifndef SDL_THREADS_DISABLED
	SDL_UnlockMutex(SDL_generic_TLS_mutex);
	#endif

	return storage;
	}

	int SDL_Generic_SetTLSData(SDL_TLSData *data)
	{
	SDL_ThreadID thread = SDL_GetCurrentThreadID();
	SDL_TLSEntry prev, entry;

	/* SDL_Generic_GetTLSData() is always called first, so we can assume SDL_generic_TLS_mutex */
	SDL_LockMutex(SDL_generic_TLS_mutex);
	prev = NULL;
	for (entry = SDL_generic_TLS; entry; entry = entry->next) {
	if (entry->thread == thread) {
	if (data) {
	entry->storage = data;
	} else {
	if (prev) {
	prev->next = entry->next;
	} else {
	SDL_generic_TLS = entry->next;
	}
	SDL_free(entry);
	}
	break;
	}
	prev = entry;
	}
	if (!entry) {
	entry = (SDL_TLSEntry )SDL_malloc(sizeof(entry));
	if (entry) {
	entry->thread = thread;
	entry->storage = data;
	entry->next = SDL_generic_TLS;
	SDL_generic_TLS = entry;
	}
	}
	SDL_UnlockMutex(SDL_generic_TLS_mutex);

	return entry ? 0 : -1;
	}

	/* Non-thread-safe global error variable */
	static SDL_error *SDL_GetStaticErrBuf(void)
	{
	static SDL_error SDL_global_error;
	static char SDL_global_error_str[128];
	SDL_global_error.str = SDL_global_error_str;
	SDL_global_error.len = sizeof(SDL_global_error_str);
	return &SDL_global_error;
	}

	#ifndef SDL_THREADS_DISABLED
	static void SDLCALL SDL_FreeErrBuf(void *data)
	{
	SDL_error errbuf = (SDL_error )data;

	if (errbuf->str) {
	errbuf->free_func(errbuf->str);
	}
	errbuf->free_func(errbuf);
	}
	#endif

	/* Routine to get the thread-specific error variable */
	SDL_error *SDL_GetErrBuf(SDL_bool create)
	{
	#ifdef SDL_THREADS_DISABLED
	return SDL_GetStaticErrBuf();
	#else
	static SDL_SpinLock tls_lock;
	static SDL_bool tls_being_created;
	static SDL_TLSID tls_errbuf;
	const SDL_error ALLOCATION_IN_PROGRESS = (SDL_error )-1;
	SDL_error *errbuf;

	if (!tls_errbuf && !create) {
	return NULL;
	}

	/* tls_being_created is there simply to prevent recursion if SDL_CreateTLS() fails.
	It also means it's possible for another thread to also use SDL_global_errbuf,
	but that's very unlikely and hopefully won't cause issues.
	*/
	if (!tls_errbuf && !tls_being_created) {
	SDL_LockSpinlock(&tls_lock);
	if (!tls_errbuf) {
	SDL_TLSID slot;
	tls_being_created = SDL_TRUE;
	slot = SDL_CreateTLS();
	tls_being_created = SDL_FALSE;
	SDL_MemoryBarrierRelease();
	tls_errbuf = slot;
	}
	SDL_UnlockSpinlock(&tls_lock);
	}
	if (!tls_errbuf) {
	return SDL_GetStaticErrBuf();
	}

	SDL_MemoryBarrierAcquire();
	errbuf = (SDL_error *)SDL_GetTLS(tls_errbuf);
	if (errbuf == ALLOCATION_IN_PROGRESS) {
	return SDL_GetStaticErrBuf();
	}
	if (!errbuf) {
	/* Get the original memory functions for this allocation because the lifetime
	* of the error buffer may span calls to SDL_SetMemoryFunctions() by the app
	*/
	SDL_realloc_func realloc_func;
	SDL_free_func free_func;
	SDL_GetOriginalMemoryFunctions(NULL, NULL, &realloc_func, &free_func);

	/* Mark that we're in the middle of allocating our buffer */
	SDL_SetTLS(tls_errbuf, ALLOCATION_IN_PROGRESS, NULL);
	errbuf = (SDL_error )realloc_func(NULL, sizeof(errbuf));
	if (!errbuf) {
	SDL_SetTLS(tls_errbuf, NULL, NULL);
	return SDL_GetStaticErrBuf();
	}
	SDL_zerop(errbuf);
	errbuf->realloc_func = realloc_func;
	errbuf->free_func = free_func;
	SDL_SetTLS(tls_errbuf, errbuf, SDL_FreeErrBuf);
	}
	return errbuf;
	#endif /* SDL_THREADS_DISABLED */
	}

	void SDL_RunThread(SDL_Thread *thread)
	{
	void *userdata = thread->userdata;
	int(SDLCALL * userfunc)(void *) = thread->userfunc;

	int *statusloc = &thread->status;

	/* Perform any system-dependent setup - this function may not fail */
	SDL_SYS_SetupThread(thread->name);

	/* Get the thread id */
	thread->threadid = SDL_GetCurrentThreadID();

	/* Run the function */
	*statusloc = userfunc(userdata);

	/* Clean up thread-local storage */
	SDL_CleanupTLS();

	/* Mark us as ready to be joined (or detached) */
	if (!SDL_AtomicCompareAndSwap(&thread->state, SDL_THREAD_STATE_ALIVE, SDL_THREAD_STATE_ZOMBIE)) {
	/* Clean up if something already detached us. */
	if (SDL_AtomicCompareAndSwap(&thread->state, SDL_THREAD_STATE_DETACHED, SDL_THREAD_STATE_CLEANED)) {
	if (thread->name) {
	SDL_free(thread->name);
	}
	SDL_free(thread);
	}
	}
	}

	#ifdef SDL_CreateThread
	#undef SDL_CreateThread
	#undef SDL_CreateThreadWithStackSize
	#endif
	#if SDL_DYNAMIC_API
	#define SDL_CreateThread SDL_CreateThread_REAL
	#define SDL_CreateThreadWithStackSize SDL_CreateThreadWithStackSize_REAL
	#endif

	#ifdef SDL_PASSED_BEGINTHREAD_ENDTHREAD
	SDL_Thread SDL_CreateThreadWithStackSize(int(SDLCALL fn)(void *),
	const char name, const size_t stacksize, void data,
	pfnSDL_CurrentBeginThread pfnBeginThread,
	pfnSDL_CurrentEndThread pfnEndThread)
	#else
	SDL_Thread SDL_CreateThreadWithStackSize(int(SDLCALL fn)(void *),
	const char name, const size_t stacksize, void data)
	#endif
	{
	SDL_Thread *thread;
	int ret;

	/* Allocate memory for the thread info structure */
	thread = (SDL_Thread )SDL_calloc(1, sizeof(thread));
	if (!thread) {
	return NULL;
	}
	thread->status = -1;
	SDL_AtomicSet(&thread->state, SDL_THREAD_STATE_ALIVE);

	/* Set up the arguments for the thread */
	if (name) {
	thread->name = SDL_strdup(name);
	if (!thread->name) {
	SDL_free(thread);
	return NULL;
	}
	}

	thread->userfunc = fn;
	thread->userdata = data;
	thread->stacksize = stacksize;

	/* Create the thread and go! */
	#ifdef SDL_PASSED_BEGINTHREAD_ENDTHREAD
	ret = SDL_SYS_CreateThread(thread, pfnBeginThread, pfnEndThread);
	#else
	ret = SDL_SYS_CreateThread(thread);
	#endif
	if (ret < 0) {
	/* Oops, failed. Gotta free everything */
	SDL_free(thread->name);
	SDL_free(thread);
	thread = NULL;
	}

	/* Everything is running now */
	return thread;
	}

	#ifdef SDL_PASSED_BEGINTHREAD_ENDTHREAD
	DECLSPEC SDL_Thread SDLCALL SDL_CreateThread(int(SDLCALL fn)(void *),
	const char name, void data,
	pfnSDL_CurrentBeginThread pfnBeginThread,
	pfnSDL_CurrentEndThread pfnEndThread)
	#else
	DECLSPEC SDL_Thread SDLCALL SDL_CreateThread(int(SDLCALL fn)(void *),
	const char name, void data)
	#endif
	{
	#ifdef SDL_PASSED_BEGINTHREAD_ENDTHREAD
	return SDL_CreateThreadWithStackSize(fn, name, 0, data, pfnBeginThread, pfnEndThread);
	#else
	return SDL_CreateThreadWithStackSize(fn, name, 0, data);
	#endif
	}

	SDL_Thread SDL_CreateThreadInternal(int(SDLCALL fn)(void ), const char name,
	const size_t stacksize, void *data)
	{
	#ifdef SDL_PASSED_BEGINTHREAD_ENDTHREAD
	return SDL_CreateThreadWithStackSize(fn, name, stacksize, data, NULL, NULL);
	#else
	return SDL_CreateThreadWithStackSize(fn, name, stacksize, data);
	#endif
	}

	SDL_ThreadID SDL_GetThreadID(SDL_Thread *thread)
	{
	SDL_ThreadID id;

	if (thread) {
	id = thread->threadid;
	} else {
	id = SDL_GetCurrentThreadID();
	}
	return id;
	}

	const char SDL_GetThreadName(SDL_Thread thread)
	{
	if (thread) {
	return thread->name;
	} else {
	return NULL;
	}
	}

	int SDL_SetThreadPriority(SDL_ThreadPriority priority)
	{
	return SDL_SYS_SetThreadPriority(priority);
	}

	void SDL_WaitThread(SDL_Thread thread, int status)
	{
	if (thread) {
	SDL_SYS_WaitThread(thread);
	if (status) {
	*status = thread->status;
	}
	if (thread->name) {
	SDL_free(thread->name);
	}
	SDL_free(thread);
	}
	}

	void SDL_DetachThread(SDL_Thread *thread)
	{
	if (!thread) {
	return;
	}

	/* Grab dibs if the state is alive+joinable. */
	if (SDL_AtomicCompareAndSwap(&thread->state, SDL_THREAD_STATE_ALIVE, SDL_THREAD_STATE_DETACHED)) {
	SDL_SYS_DetachThread(thread);
	} else {
	/* all other states are pretty final, see where we landed. */
	const int thread_state = SDL_AtomicGet(&thread->state);
	if ((thread_state == SDL_THREAD_STATE_DETACHED) \|\| (thread_state == SDL_THREAD_STATE_CLEANED)) {
	return; /* already detached (you shouldn't call this twice!) */
	} else if (thread_state == SDL_THREAD_STATE_ZOMBIE) {
	SDL_WaitThread(thread, NULL); /* already done, clean it up. */
	} else {
	SDL_assert(0 && "Unexpected thread state");
	}
	}
	}

	int SDL_WaitSemaphore(SDL_Semaphore *sem)
	{
	return SDL_WaitSemaphoreTimeoutNS(sem, -1);
	}

	int SDL_TryWaitSemaphore(SDL_Semaphore *sem)
	{
	return SDL_WaitSemaphoreTimeoutNS(sem, 0);
	}

	int SDL_WaitSemaphoreTimeout(SDL_Semaphore *sem, Sint32 timeoutMS)
	{
	Sint64 timeoutNS;

	if (timeoutMS >= 0) {
	timeoutNS = SDL_MS_TO_NS(timeoutMS);
	} else {
	timeoutNS = -1;
	}
	return SDL_WaitSemaphoreTimeoutNS(sem, timeoutNS);
	}

	int SDL_WaitCondition(SDL_Condition cond, SDL_Mutex mutex)
	{
	return SDL_WaitConditionTimeoutNS(cond, mutex, -1);
	}

	int SDL_WaitConditionTimeout(SDL_Condition cond, SDL_Mutex mutex, Sint32 timeoutMS)
	{
	Sint64 timeoutNS;

	if (timeoutMS >= 0) {
	timeoutNS = SDL_MS_TO_NS(timeoutMS);
	} else {
	timeoutNS = -1;
	}
	return SDL_WaitConditionTimeoutNS(cond, mutex, timeoutNS);
	}