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+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2022 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_thread_h_
+#define SDL_thread_h_
+
+/**
+ *  \file SDL_thread.h
+ *
+ *  Header for the SDL thread management routines.
+ */
+
+#include "SDL_stdinc.h"
+#include "SDL_error.h"
+
+/* Thread synchronization primitives */
+#include "SDL_atomic.h"
+#include "SDL_mutex.h"
+
+#if defined(__WIN32__)
+#include <process.h> /* _beginthreadex() and _endthreadex() */
+#endif
+#if defined(__OS2__) /* for _beginthread() and _endthread() */
+#ifndef __EMX__
+#include <process.h>
+#else
+#include <stdlib.h>
+#endif
+#endif
+
+#include "begin_code.h"
+/* Set up for C function definitions, even when using C++ */
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* The SDL thread structure, defined in SDL_thread.c */
+struct SDL_Thread;
+typedef struct SDL_Thread SDL_Thread;
+
+/* The SDL thread ID */
+typedef unsigned long SDL_threadID;
+
+/* Thread local storage ID, 0 is the invalid ID */
+typedef unsigned int SDL_TLSID;
+
+/**
+ *  The SDL thread priority.
+ *
+ *  SDL will make system changes as necessary in order to apply the thread priority.
+ *  Code which attempts to control thread state related to priority should be aware
+ *  that calling SDL_SetThreadPriority may alter such state.
+ *  SDL_HINT_THREAD_PRIORITY_POLICY can be used to control aspects of this behavior.
+ *
+ *  \note On many systems you require special privileges to set high or time critical priority.
+ */
+typedef enum {
+    SDL_THREAD_PRIORITY_LOW,
+    SDL_THREAD_PRIORITY_NORMAL,
+    SDL_THREAD_PRIORITY_HIGH,
+    SDL_THREAD_PRIORITY_TIME_CRITICAL
+} SDL_ThreadPriority;
+
+/**
+ * The function passed to SDL_CreateThread().
+ *
+ * \param data what was passed as `data` to SDL_CreateThread()
+ * \returns a value that can be reported through SDL_WaitThread().
+ */
+typedef int (SDLCALL * SDL_ThreadFunction) (void *data);
+
+
+#if defined(__WIN32__)
+/**
+ *  \file SDL_thread.h
+ *
+ *  We compile SDL into a DLL. This means, that it's the DLL which
+ *  creates a new thread for the calling process with the SDL_CreateThread()
+ *  API. There is a problem with this, that only the RTL of the SDL2.DLL will
+ *  be initialized for those threads, and not the RTL of the calling
+ *  application!
+ *
+ *  To solve this, we make a little hack here.
+ *
+ *  We'll always use the caller's _beginthread() and _endthread() APIs to
+ *  start a new thread. This way, if it's the SDL2.DLL which uses this API,
+ *  then the RTL of SDL2.DLL will be used to create the new thread, and if it's
+ *  the application, then the RTL of the application will be used.
+ *
+ *  So, in short:
+ *  Always use the _beginthread() and _endthread() of the calling runtime
+ *  library!
+ */
+#define SDL_PASSED_BEGINTHREAD_ENDTHREAD
+
+typedef uintptr_t (__cdecl * pfnSDL_CurrentBeginThread)
+                   (void *, unsigned, unsigned (__stdcall *func)(void *),
+                    void * /*arg*/, unsigned, unsigned * /* threadID */);
+typedef void (__cdecl * pfnSDL_CurrentEndThread) (unsigned code);
+
+#ifndef SDL_beginthread
+#define SDL_beginthread _beginthreadex
+#endif
+#ifndef SDL_endthread
+#define SDL_endthread _endthreadex
+#endif
+
+extern DECLSPEC SDL_Thread *SDLCALL
+SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
+                 pfnSDL_CurrentBeginThread pfnBeginThread,
+                 pfnSDL_CurrentEndThread pfnEndThread);
+
+extern DECLSPEC SDL_Thread *SDLCALL
+SDL_CreateThreadWithStackSize(int (SDLCALL * fn) (void *),
+                 const char *name, const size_t stacksize, void *data,
+                 pfnSDL_CurrentBeginThread pfnBeginThread,
+                 pfnSDL_CurrentEndThread pfnEndThread);
+
+
+#if defined(SDL_CreateThread) && SDL_DYNAMIC_API
+#undef SDL_CreateThread
+#define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
+#undef SDL_CreateThreadWithStackSize
+#define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize_REAL(fn, name, stacksize, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
+#else
+#define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
+#define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize(fn, name, data, (pfnSDL_CurrentBeginThread)_beginthreadex, (pfnSDL_CurrentEndThread)SDL_endthread)
+#endif
+
+#elif defined(__OS2__)
+/*
+ * just like the windows case above:  We compile SDL2
+ * into a dll with Watcom's runtime statically linked.
+ */
+#define SDL_PASSED_BEGINTHREAD_ENDTHREAD
+
+typedef int (*pfnSDL_CurrentBeginThread)(void (*func)(void *), void *, unsigned, void * /*arg*/);
+typedef void (*pfnSDL_CurrentEndThread)(void);
+
+#ifndef SDL_beginthread
+#define SDL_beginthread _beginthread
+#endif
+#ifndef SDL_endthread
+#define SDL_endthread _endthread
+#endif
+
+extern DECLSPEC SDL_Thread *SDLCALL
+SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data,
+                 pfnSDL_CurrentBeginThread pfnBeginThread,
+                 pfnSDL_CurrentEndThread pfnEndThread);
+extern DECLSPEC SDL_Thread *SDLCALL
+SDL_CreateThreadWithStackSize(SDL_ThreadFunction fn, const char *name, const size_t stacksize, void *data,
+                 pfnSDL_CurrentBeginThread pfnBeginThread,
+                 pfnSDL_CurrentEndThread pfnEndThread);
+
+#if defined(SDL_CreateThread) && SDL_DYNAMIC_API
+#undef SDL_CreateThread
+#define SDL_CreateThread(fn, name, data) SDL_CreateThread_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
+#undef SDL_CreateThreadWithStackSize
+#define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize_REAL(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
+#else
+#define SDL_CreateThread(fn, name, data) SDL_CreateThread(fn, name, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
+#define SDL_CreateThreadWithStackSize(fn, name, stacksize, data) SDL_CreateThreadWithStackSize(fn, name, stacksize, data, (pfnSDL_CurrentBeginThread)SDL_beginthread, (pfnSDL_CurrentEndThread)SDL_endthread)
+#endif
+
+#else
+
+/**
+ * Create a new thread with a default stack size.
+ *
+ * This is equivalent to calling:
+ *
+ * ```c
+ * SDL_CreateThreadWithStackSize(fn, name, 0, data);
+ * ```
+ *
+ * \param fn the SDL_ThreadFunction function to call in the new thread
+ * \param name the name of the thread
+ * \param data a pointer that is passed to `fn`
+ * \returns an opaque pointer to the new thread object on success, NULL if the
+ *          new thread could not be created; call SDL_GetError() for more
+ *          information.
+ *
+ * \since This function is available since SDL 2.0.0.
+ *
+ * \sa SDL_CreateThreadWithStackSize
+ * \sa SDL_WaitThread
+ */
+extern DECLSPEC SDL_Thread *SDLCALL
+SDL_CreateThread(SDL_ThreadFunction fn, const char *name, void *data);
+
+/**
+ * Create a new thread with a specific stack size.
+ *
+ * SDL makes an attempt to report `name` to the system, so that debuggers can
+ * display it. Not all platforms support this.
+ *
+ * Thread naming is a little complicated: Most systems have very small limits
+ * for the string length (Haiku has 32 bytes, Linux currently has 16, Visual
+ * C++ 6.0 has _nine_!), and possibly other arbitrary rules. You'll have to
+ * see what happens with your system's debugger. The name should be UTF-8 (but
+ * using the naming limits of C identifiers is a better bet). There are no
+ * requirements for thread naming conventions, so long as the string is
+ * null-terminated UTF-8, but these guidelines are helpful in choosing a name:
+ *
+ * https://stackoverflow.com/questions/149932/naming-conventions-for-threads
+ *
+ * If a system imposes requirements, SDL will try to munge the string for it
+ * (truncate, etc), but the original string contents will be available from
+ * SDL_GetThreadName().
+ *
+ * The size (in bytes) of the new stack can be specified. Zero means "use the
+ * system default" which might be wildly different between platforms. x86
+ * Linux generally defaults to eight megabytes, an embedded device might be a
+ * few kilobytes instead. You generally need to specify a stack that is a
+ * multiple of the system's page size (in many cases, this is 4 kilobytes, but
+ * check your system documentation).
+ *
+ * In SDL 2.1, stack size will be folded into the original SDL_CreateThread
+ * function, but for backwards compatibility, this is currently a separate
+ * function.
+ *
+ * \param fn the SDL_ThreadFunction function to call in the new thread
+ * \param name the name of the thread
+ * \param stacksize the size, in bytes, to allocate for the new thread stack.
+ * \param data a pointer that is passed to `fn`
+ * \returns an opaque pointer to the new thread object on success, NULL if the
+ *          new thread could not be created; call SDL_GetError() for more
+ *          information.
+ *
+ * \since This function is available since SDL 2.0.9.
+ *
+ * \sa SDL_WaitThread
+ */
+extern DECLSPEC SDL_Thread *SDLCALL
+SDL_CreateThreadWithStackSize(SDL_ThreadFunction fn, const char *name, const size_t stacksize, void *data);
+
+#endif
+
+/**
+ * Get the thread name as it was specified in SDL_CreateThread().
+ *
+ * This is internal memory, not to be freed by the caller, and remains valid
+ * until the specified thread is cleaned up by SDL_WaitThread().
+ *
+ * \param thread the thread to query
+ * \returns a pointer to a UTF-8 string that names the specified thread, or
+ *          NULL if it doesn't have a name.
+ *
+ * \since This function is available since SDL 2.0.0.
+ *
+ * \sa SDL_CreateThread
+ */
+extern DECLSPEC const char *SDLCALL SDL_GetThreadName(SDL_Thread *thread);
+
+/**
+ * Get the thread identifier for the current thread.
+ *
+ * This thread identifier is as reported by the underlying operating system.
+ * If SDL is running on a platform that does not support threads the return
+ * value will always be zero.
+ *
+ * This function also returns a valid thread ID when called from the main
+ * thread.
+ *
+ * \returns the ID of the current thread.
+ *
+ * \since This function is available since SDL 2.0.0.
+ *
+ * \sa SDL_GetThreadID
+ */
+extern DECLSPEC SDL_threadID SDLCALL SDL_ThreadID(void);
+
+/**
+ * Get the thread identifier for the specified thread.
+ *
+ * This thread identifier is as reported by the underlying operating system.
+ * If SDL is running on a platform that does not support threads the return
+ * value will always be zero.
+ *
+ * \param thread the thread to query
+ * \returns the ID of the specified thread, or the ID of the current thread if
+ *          `thread` is NULL.
+ *
+ * \since This function is available since SDL 2.0.0.
+ *
+ * \sa SDL_ThreadID
+ */
+extern DECLSPEC SDL_threadID SDLCALL SDL_GetThreadID(SDL_Thread * thread);
+
+/**
+ * Set the priority for the current thread.
+ *
+ * Note that some platforms will not let you alter the priority (or at least,
+ * promote the thread to a higher priority) at all, and some require you to be
+ * an administrator account. Be prepared for this to fail.
+ *
+ * \param priority the SDL_ThreadPriority to set
+ * \returns 0 on success or a negative error code on failure; call
+ *          SDL_GetError() for more information.
+ *
+ * \since This function is available since SDL 2.0.0.
+ */
+extern DECLSPEC int SDLCALL SDL_SetThreadPriority(SDL_ThreadPriority priority);
+
+/**
+ * Wait for a thread to finish.
+ *
+ * Threads that haven't been detached will remain (as a "zombie") until this
+ * function cleans them up. Not doing so is a resource leak.
+ *
+ * Once a thread has been cleaned up through this function, the SDL_Thread
+ * that references it becomes invalid and should not be referenced again. As
+ * such, only one thread may call SDL_WaitThread() on another.
+ *
+ * The return code for the thread function is placed in the area pointed to by
+ * `status`, if `status` is not NULL.
+ *
+ * You may not wait on a thread that has been used in a call to
+ * SDL_DetachThread(). Use either that function or this one, but not both, or
+ * behavior is undefined.
+ *
+ * It is safe to pass a NULL thread to this function; it is a no-op.
+ *
+ * Note that the thread pointer is freed by this function and is not valid
+ * afterward.
+ *
+ * \param thread the SDL_Thread pointer that was returned from the
+ *               SDL_CreateThread() call that started this thread
+ * \param status pointer to an integer that will receive the value returned
+ *               from the thread function by its 'return', or NULL to not
+ *               receive such value back.
+ *
+ * \since This function is available since SDL 2.0.0.
+ *
+ * \sa SDL_CreateThread
+ * \sa SDL_DetachThread
+ */
+extern DECLSPEC void SDLCALL SDL_WaitThread(SDL_Thread * thread, int *status);
+
+/**
+ * Let a thread clean up on exit without intervention.
+ *
+ * A thread may be "detached" to signify that it should not remain until
+ * another thread has called SDL_WaitThread() on it. Detaching a thread is
+ * useful for long-running threads that nothing needs to synchronize with or
+ * further manage. When a detached thread is done, it simply goes away.
+ *
+ * There is no way to recover the return code of a detached thread. If you
+ * need this, don't detach the thread and instead use SDL_WaitThread().
+ *
+ * Once a thread is detached, you should usually assume the SDL_Thread isn't
+ * safe to reference again, as it will become invalid immediately upon the
+ * detached thread's exit, instead of remaining until someone has called
+ * SDL_WaitThread() to finally clean it up. As such, don't detach the same
+ * thread more than once.
+ *
+ * If a thread has already exited when passed to SDL_DetachThread(), it will
+ * stop waiting for a call to SDL_WaitThread() and clean up immediately. It is
+ * not safe to detach a thread that might be used with SDL_WaitThread().
+ *
+ * You may not call SDL_WaitThread() on a thread that has been detached. Use
+ * either that function or this one, but not both, or behavior is undefined.
+ *
+ * It is safe to pass NULL to this function; it is a no-op.
+ *
+ * \param thread the SDL_Thread pointer that was returned from the
+ *               SDL_CreateThread() call that started this thread
+ *
+ * \since This function is available since SDL 2.0.2.
+ *
+ * \sa SDL_CreateThread
+ * \sa SDL_WaitThread
+ */
+extern DECLSPEC void SDLCALL SDL_DetachThread(SDL_Thread * thread);
+
+/**
+ * Create a piece of thread-local storage.
+ *
+ * This creates an identifier that is globally visible to all threads but
+ * refers to data that is thread-specific.
+ *
+ * \returns the newly created thread local storage identifier or 0 on error.
+ *
+ * \since This function is available since SDL 2.0.0.
+ *
+ * \sa SDL_TLSGet
+ * \sa SDL_TLSSet
+ */
+extern DECLSPEC SDL_TLSID SDLCALL SDL_TLSCreate(void);
+
+/**
+ * Get the current thread's value associated with a thread local storage ID.
+ *
+ * \param id the thread local storage ID
+ * \returns the value associated with the ID for the current thread or NULL if
+ *          no value has been set; call SDL_GetError() for more information.
+ *
+ * \since This function is available since SDL 2.0.0.
+ *
+ * \sa SDL_TLSCreate
+ * \sa SDL_TLSSet
+ */
+extern DECLSPEC void * SDLCALL SDL_TLSGet(SDL_TLSID id);
+
+/**
+ * Set the current thread's value associated with a thread local storage ID.
+ *
+ * The function prototype for `destructor` is:
+ *
+ * ```c
+ * void destructor(void *value)
+ * ```
+ *
+ * where its parameter `value` is what was passed as `value` to SDL_TLSSet().
+ *
+ * \param id the thread local storage ID
+ * \param value the value to associate with the ID for the current thread
+ * \param destructor a function called when the thread exits, to free the
+ *                   value
+ * \returns 0 on success or a negative error code on failure; call
+ *          SDL_GetError() for more information.
+ *
+ * \since This function is available since SDL 2.0.0.
+ *
+ * \sa SDL_TLSCreate
+ * \sa SDL_TLSGet
+ */
+extern DECLSPEC int SDLCALL SDL_TLSSet(SDL_TLSID id, const void *value, void (SDLCALL *destructor)(void*));
+
+/**
+ * Cleanup all TLS data for this thread.
+ *
+ * \since This function is available since SDL 2.0.16.
+ */
+extern DECLSPEC void SDLCALL SDL_TLSCleanup(void);
+
+/* Ends C function definitions when using C++ */
+#ifdef __cplusplus
+}
+#endif
+#include "close_code.h"
+
+#endif /* SDL_thread_h_ */
+
+/* vi: set ts=4 sw=4 expandtab: */