--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SDL3/SDL_asyncio.h	Mon Jan 05 02:15:46 2026 -0500
@@ -0,0 +1,546 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2025 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.
+*/
+
+/* WIKI CATEGORY: AsyncIO */
+
+/**
+ * # CategoryAsyncIO
+ *
+ * SDL offers a way to perform I/O asynchronously. This allows an app to read
+ * or write files without waiting for data to actually transfer; the functions
+ * that request I/O never block while the request is fulfilled.
+ *
+ * Instead, the data moves in the background and the app can check for results
+ * at their leisure.
+ *
+ * This is more complicated than just reading and writing files in a
+ * synchronous way, but it can allow for more efficiency, and never having
+ * framerate drops as the hard drive catches up, etc.
+ *
+ * The general usage pattern for async I/O is:
+ *
+ * - Create one or more SDL_AsyncIOQueue objects.
+ * - Open files with SDL_AsyncIOFromFile.
+ * - Start I/O tasks to the files with SDL_ReadAsyncIO or SDL_WriteAsyncIO,
+ *   putting those tasks into one of the queues.
+ * - Later on, use SDL_GetAsyncIOResult on a queue to see if any task is
+ *   finished without blocking. Tasks might finish in any order with success
+ *   or failure.
+ * - When all your tasks are done, close the file with SDL_CloseAsyncIO. This
+ *   also generates a task, since it might flush data to disk!
+ *
+ * This all works, without blocking, in a single thread, but one can also wait
+ * on a queue in a background thread, sleeping until new results have arrived:
+ *
+ * - Call SDL_WaitAsyncIOResult from one or more threads to efficiently block
+ *   until new tasks complete.
+ * - When shutting down, call SDL_SignalAsyncIOQueue to unblock any sleeping
+ *   threads despite there being no new tasks completed.
+ *
+ * And, of course, to match the synchronous SDL_LoadFile, we offer
+ * SDL_LoadFileAsync as a convenience function. This will handle allocating a
+ * buffer, slurping in the file data, and null-terminating it; you still check
+ * for results later.
+ *
+ * Behind the scenes, SDL will use newer, efficient APIs on platforms that
+ * support them: Linux's io_uring and Windows 11's IoRing, for example. If
+ * those technologies aren't available, SDL will offload the work to a thread
+ * pool that will manage otherwise-synchronous loads without blocking the app.
+ *
+ * ## Best Practices
+ *
+ * Simple non-blocking I/O--for an app that just wants to pick up data
+ * whenever it's ready without losing framerate waiting on disks to spin--can
+ * use whatever pattern works well for the program. In this case, simply call
+ * SDL_ReadAsyncIO, or maybe SDL_LoadFileAsync, as needed. Once a frame, call
+ * SDL_GetAsyncIOResult to check for any completed tasks and deal with the
+ * data as it arrives.
+ *
+ * If two separate pieces of the same program need their own I/O, it is legal
+ * for each to create their own queue. This will prevent either piece from
+ * accidentally consuming the other's completed tasks. Each queue does require
+ * some amount of resources, but it is not an overwhelming cost. Do not make a
+ * queue for each task, however. It is better to put many tasks into a single
+ * queue. They will be reported in order of completion, not in the order they
+ * were submitted, so it doesn't generally matter what order tasks are
+ * started.
+ *
+ * One async I/O queue can be shared by multiple threads, or one thread can
+ * have more than one queue, but the most efficient way--if ruthless
+ * efficiency is the goal--is to have one queue per thread, with multiple
+ * threads working in parallel, and attempt to keep each queue loaded with
+ * tasks that are both started by and consumed by the same thread. On modern
+ * platforms that can use newer interfaces, this can keep data flowing as
+ * efficiently as possible all the way from storage hardware to the app, with
+ * no contention between threads for access to the same queue.
+ *
+ * Written data is not guaranteed to make it to physical media by the time a
+ * closing task is completed, unless SDL_CloseAsyncIO is called with its
+ * `flush` parameter set to true, which is to say that a successful result
+ * here can still result in lost data during an unfortunately-timed power
+ * outage if not flushed. However, flushing will take longer and may be
+ * unnecessary, depending on the app's needs.
+ */
+
+#ifndef SDL_asyncio_h_
+#define SDL_asyncio_h_
+
+#include <SDL3/SDL_stdinc.h>
+
+#include <SDL3/SDL_begin_code.h>
+/* Set up for C function definitions, even when using C++ */
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * The asynchronous I/O operation structure.
+ *
+ * This operates as an opaque handle. One can then request read or write
+ * operations on it.
+ *
+ * \since This struct is available since SDL 3.2.0.
+ *
+ * \sa SDL_AsyncIOFromFile
+ */
+typedef struct SDL_AsyncIO SDL_AsyncIO;
+
+/**
+ * Types of asynchronous I/O tasks.
+ *
+ * \since This enum is available since SDL 3.2.0.
+ */
+typedef enum SDL_AsyncIOTaskType
+{
+    SDL_ASYNCIO_TASK_READ,   /**< A read operation. */
+    SDL_ASYNCIO_TASK_WRITE,  /**< A write operation. */
+    SDL_ASYNCIO_TASK_CLOSE   /**< A close operation. */
+} SDL_AsyncIOTaskType;
+
+/**
+ * Possible outcomes of an asynchronous I/O task.
+ *
+ * \since This enum is available since SDL 3.2.0.
+ */
+typedef enum SDL_AsyncIOResult
+{
+    SDL_ASYNCIO_COMPLETE,  /**< request was completed without error */
+    SDL_ASYNCIO_FAILURE,   /**< request failed for some reason; check SDL_GetError()! */
+    SDL_ASYNCIO_CANCELED   /**< request was canceled before completing. */
+} SDL_AsyncIOResult;
+
+/**
+ * Information about a completed asynchronous I/O request.
+ *
+ * \since This struct is available since SDL 3.2.0.
+ */
+typedef struct SDL_AsyncIOOutcome
+{
+    SDL_AsyncIO *asyncio;   /**< what generated this task. This pointer will be invalid if it was closed! */
+    SDL_AsyncIOTaskType type;  /**< What sort of task was this? Read, write, etc? */
+    SDL_AsyncIOResult result;  /**< the result of the work (success, failure, cancellation). */
+    void *buffer;  /**< buffer where data was read/written. */
+    Uint64 offset;  /**< offset in the SDL_AsyncIO where data was read/written. */
+    Uint64 bytes_requested;  /**< number of bytes the task was to read/write. */
+    Uint64 bytes_transferred;  /**< actual number of bytes that were read/written. */
+    void *userdata;    /**< pointer provided by the app when starting the task */
+} SDL_AsyncIOOutcome;
+
+/**
+ * A queue of completed asynchronous I/O tasks.
+ *
+ * When starting an asynchronous operation, you specify a queue for the new
+ * task. A queue can be asked later if any tasks in it have completed,
+ * allowing an app to manage multiple pending tasks in one place, in whatever
+ * order they complete.
+ *
+ * \since This struct is available since SDL 3.2.0.
+ *
+ * \sa SDL_CreateAsyncIOQueue
+ * \sa SDL_ReadAsyncIO
+ * \sa SDL_WriteAsyncIO
+ * \sa SDL_GetAsyncIOResult
+ * \sa SDL_WaitAsyncIOResult
+ */
+typedef struct SDL_AsyncIOQueue SDL_AsyncIOQueue;
+
+/**
+ * Use this function to create a new SDL_AsyncIO object for reading from
+ * and/or writing to a named file.
+ *
+ * The `mode` string understands the following values:
+ *
+ * - "r": Open a file for reading only. It must exist.
+ * - "w": Open a file for writing only. It will create missing files or
+ *   truncate existing ones.
+ * - "r+": Open a file for update both reading and writing. The file must
+ *   exist.
+ * - "w+": Create an empty file for both reading and writing. If a file with
+ *   the same name already exists its content is erased and the file is
+ *   treated as a new empty file.
+ *
+ * There is no "b" mode, as there is only "binary" style I/O, and no "a" mode
+ * for appending, since you specify the position when starting a task.
+ *
+ * This function supports Unicode filenames, but they must be encoded in UTF-8
+ * format, regardless of the underlying operating system.
+ *
+ * This call is _not_ asynchronous; it will open the file before returning,
+ * under the assumption that doing so is generally a fast operation. Future
+ * reads and writes to the opened file will be async, however.
+ *
+ * \param file a UTF-8 string representing the filename to open.
+ * \param mode an ASCII string representing the mode to be used for opening
+ *             the file.
+ * \returns a pointer to the SDL_AsyncIO structure that is created or NULL on
+ *          failure; call SDL_GetError() for more information.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_CloseAsyncIO
+ * \sa SDL_ReadAsyncIO
+ * \sa SDL_WriteAsyncIO
+ */
+extern SDL_DECLSPEC SDL_AsyncIO * SDLCALL SDL_AsyncIOFromFile(const char *file, const char *mode);
+
+/**
+ * Use this function to get the size of the data stream in an SDL_AsyncIO.
+ *
+ * This call is _not_ asynchronous; it assumes that obtaining this info is a
+ * non-blocking operation in most reasonable cases.
+ *
+ * \param asyncio the SDL_AsyncIO to get the size of the data stream from.
+ * \returns the size of the data stream in the SDL_IOStream on success or a
+ *          negative error code on failure; call SDL_GetError() for more
+ *          information.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.2.0.
+ */
+extern SDL_DECLSPEC Sint64 SDLCALL SDL_GetAsyncIOSize(SDL_AsyncIO *asyncio);
+
+/**
+ * Start an async read.
+ *
+ * This function reads up to `size` bytes from `offset` position in the data
+ * source to the area pointed at by `ptr`. This function may read less bytes
+ * than requested.
+ *
+ * This function returns as quickly as possible; it does not wait for the read
+ * to complete. On a successful return, this work will continue in the
+ * background. If the work begins, even failure is asynchronous: a failing
+ * return value from this function only means the work couldn't start at all.
+ *
+ * `ptr` must remain available until the work is done, and may be accessed by
+ * the system at any time until then. Do not allocate it on the stack, as this
+ * might take longer than the life of the calling function to complete!
+ *
+ * An SDL_AsyncIOQueue must be specified. The newly-created task will be added
+ * to it when it completes its work.
+ *
+ * \param asyncio a pointer to an SDL_AsyncIO structure.
+ * \param ptr a pointer to a buffer to read data into.
+ * \param offset the position to start reading in the data source.
+ * \param size the number of bytes to read from the data source.
+ * \param queue a queue to add the new SDL_AsyncIO to.
+ * \param userdata an app-defined pointer that will be provided with the task
+ *                 results.
+ * \returns true on success or false on failure; call SDL_GetError() for more
+ *          information.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_WriteAsyncIO
+ * \sa SDL_CreateAsyncIOQueue
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_ReadAsyncIO(SDL_AsyncIO *asyncio, void *ptr, Uint64 offset, Uint64 size, SDL_AsyncIOQueue *queue, void *userdata);
+
+/**
+ * Start an async write.
+ *
+ * This function writes `size` bytes from `offset` position in the data source
+ * to the area pointed at by `ptr`.
+ *
+ * This function returns as quickly as possible; it does not wait for the
+ * write to complete. On a successful return, this work will continue in the
+ * background. If the work begins, even failure is asynchronous: a failing
+ * return value from this function only means the work couldn't start at all.
+ *
+ * `ptr` must remain available until the work is done, and may be accessed by
+ * the system at any time until then. Do not allocate it on the stack, as this
+ * might take longer than the life of the calling function to complete!
+ *
+ * An SDL_AsyncIOQueue must be specified. The newly-created task will be added
+ * to it when it completes its work.
+ *
+ * \param asyncio a pointer to an SDL_AsyncIO structure.
+ * \param ptr a pointer to a buffer to write data from.
+ * \param offset the position to start writing to the data source.
+ * \param size the number of bytes to write to the data source.
+ * \param queue a queue to add the new SDL_AsyncIO to.
+ * \param userdata an app-defined pointer that will be provided with the task
+ *                 results.
+ * \returns true on success or false on failure; call SDL_GetError() for more
+ *          information.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_ReadAsyncIO
+ * \sa SDL_CreateAsyncIOQueue
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_WriteAsyncIO(SDL_AsyncIO *asyncio, void *ptr, Uint64 offset, Uint64 size, SDL_AsyncIOQueue *queue, void *userdata);
+
+/**
+ * Close and free any allocated resources for an async I/O object.
+ *
+ * Closing a file is _also_ an asynchronous task! If a write failure were to
+ * happen during the closing process, for example, the task results will
+ * report it as usual.
+ *
+ * Closing a file that has been written to does not guarantee the data has
+ * made it to physical media; it may remain in the operating system's file
+ * cache, for later writing to disk. This means that a successfully-closed
+ * file can be lost if the system crashes or loses power in this small window.
+ * To prevent this, call this function with the `flush` parameter set to true.
+ * This will make the operation take longer, and perhaps increase system load
+ * in general, but a successful result guarantees that the data has made it to
+ * physical storage. Don't use this for temporary files, caches, and
+ * unimportant data, and definitely use it for crucial irreplaceable files,
+ * like game saves.
+ *
+ * This function guarantees that the close will happen after any other pending
+ * tasks to `asyncio`, so it's safe to open a file, start several operations,
+ * close the file immediately, then check for all results later. This function
+ * will not block until the tasks have completed.
+ *
+ * Once this function returns true, `asyncio` is no longer valid, regardless
+ * of any future outcomes. Any completed tasks might still contain this
+ * pointer in their SDL_AsyncIOOutcome data, in case the app was using this
+ * value to track information, but it should not be used again.
+ *
+ * If this function returns false, the close wasn't started at all, and it's
+ * safe to attempt to close again later.
+ *
+ * An SDL_AsyncIOQueue must be specified. The newly-created task will be added
+ * to it when it completes its work.
+ *
+ * \param asyncio a pointer to an SDL_AsyncIO structure to close.
+ * \param flush true if data should sync to disk before the task completes.
+ * \param queue a queue to add the new SDL_AsyncIO to.
+ * \param userdata an app-defined pointer that will be provided with the task
+ *                 results.
+ * \returns true on success or false on failure; call SDL_GetError() for more
+ *          information.
+ *
+ * \threadsafety It is safe to call this function from any thread, but two
+ *               threads should not attempt to close the same object.
+ *
+ * \since This function is available since SDL 3.2.0.
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_CloseAsyncIO(SDL_AsyncIO *asyncio, bool flush, SDL_AsyncIOQueue *queue, void *userdata);
+
+/**
+ * Create a task queue for tracking multiple I/O operations.
+ *
+ * Async I/O operations are assigned to a queue when started. The queue can be
+ * checked for completed tasks thereafter.
+ *
+ * \returns a new task queue object or NULL if there was an error; call
+ *          SDL_GetError() for more information.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_DestroyAsyncIOQueue
+ * \sa SDL_GetAsyncIOResult
+ * \sa SDL_WaitAsyncIOResult
+ */
+extern SDL_DECLSPEC SDL_AsyncIOQueue * SDLCALL SDL_CreateAsyncIOQueue(void);
+
+/**
+ * Destroy a previously-created async I/O task queue.
+ *
+ * If there are still tasks pending for this queue, this call will block until
+ * those tasks are finished. All those tasks will be deallocated. Their
+ * results will be lost to the app.
+ *
+ * Any pending reads from SDL_LoadFileAsync() that are still in this queue
+ * will have their buffers deallocated by this function, to prevent a memory
+ * leak.
+ *
+ * Once this function is called, the queue is no longer valid and should not
+ * be used, including by other threads that might access it while destruction
+ * is blocking on pending tasks.
+ *
+ * Do not destroy a queue that still has threads waiting on it through
+ * SDL_WaitAsyncIOResult(). You can call SDL_SignalAsyncIOQueue() first to
+ * unblock those threads, and take measures (such as SDL_WaitThread()) to make
+ * sure they have finished their wait and won't wait on the queue again.
+ *
+ * \param queue the task queue to destroy.
+ *
+ * \threadsafety It is safe to call this function from any thread, so long as
+ *               no other thread is waiting on the queue with
+ *               SDL_WaitAsyncIOResult.
+ *
+ * \since This function is available since SDL 3.2.0.
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_DestroyAsyncIOQueue(SDL_AsyncIOQueue *queue);
+
+/**
+ * Query an async I/O task queue for completed tasks.
+ *
+ * If a task assigned to this queue has finished, this will return true and
+ * fill in `outcome` with the details of the task. If no task in the queue has
+ * finished, this function will return false. This function does not block.
+ *
+ * If a task has completed, this function will free its resources and the task
+ * pointer will no longer be valid. The task will be removed from the queue.
+ *
+ * It is safe for multiple threads to call this function on the same queue at
+ * once; a completed task will only go to one of the threads.
+ *
+ * \param queue the async I/O task queue to query.
+ * \param outcome details of a finished task will be written here. May not be
+ *                NULL.
+ * \returns true if a task has completed, false otherwise.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_WaitAsyncIOResult
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_GetAsyncIOResult(SDL_AsyncIOQueue *queue, SDL_AsyncIOOutcome *outcome);
+
+/**
+ * Block until an async I/O task queue has a completed task.
+ *
+ * This function puts the calling thread to sleep until there a task assigned
+ * to the queue that has finished.
+ *
+ * If a task assigned to the queue has finished, this will return true and
+ * fill in `outcome` with the details of the task. If no task in the queue has
+ * finished, this function will return false.
+ *
+ * If a task has completed, this function will free its resources and the task
+ * pointer will no longer be valid. The task will be removed from the queue.
+ *
+ * It is safe for multiple threads to call this function on the same queue at
+ * once; a completed task will only go to one of the threads.
+ *
+ * Note that by the nature of various platforms, more than one waiting thread
+ * may wake to handle a single task, but only one will obtain it, so
+ * `timeoutMS` is a _maximum_ wait time, and this function may return false
+ * sooner.
+ *
+ * This function may return false if there was a system error, the OS
+ * inadvertently awoke multiple threads, or if SDL_SignalAsyncIOQueue() was
+ * called to wake up all waiting threads without a finished task.
+ *
+ * A timeout can be used to specify a maximum wait time, but rather than
+ * polling, it is possible to have a timeout of -1 to wait forever, and use
+ * SDL_SignalAsyncIOQueue() to wake up the waiting threads later.
+ *
+ * \param queue the async I/O task queue to wait on.
+ * \param outcome details of a finished task will be written here. May not be
+ *                NULL.
+ * \param timeoutMS the maximum time to wait, in milliseconds, or -1 to wait
+ *                  indefinitely.
+ * \returns true if task has completed, false otherwise.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_SignalAsyncIOQueue
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_WaitAsyncIOResult(SDL_AsyncIOQueue *queue, SDL_AsyncIOOutcome *outcome, Sint32 timeoutMS);
+
+/**
+ * Wake up any threads that are blocking in SDL_WaitAsyncIOResult().
+ *
+ * This will unblock any threads that are sleeping in a call to
+ * SDL_WaitAsyncIOResult for the specified queue, and cause them to return
+ * from that function.
+ *
+ * This can be useful when destroying a queue to make sure nothing is touching
+ * it indefinitely. In this case, once this call completes, the caller should
+ * take measures to make sure any previously-blocked threads have returned
+ * from their wait and will not touch the queue again (perhaps by setting a
+ * flag to tell the threads to terminate and then using SDL_WaitThread() to
+ * make sure they've done so).
+ *
+ * \param queue the async I/O task queue to signal.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_WaitAsyncIOResult
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_SignalAsyncIOQueue(SDL_AsyncIOQueue *queue);
+
+/**
+ * Load all the data from a file path, asynchronously.
+ *
+ * This function returns as quickly as possible; it does not wait for the read
+ * to complete. On a successful return, this work will continue in the
+ * background. If the work begins, even failure is asynchronous: a failing
+ * return value from this function only means the work couldn't start at all.
+ *
+ * The data is allocated with a zero byte at the end (null terminated) for
+ * convenience. This extra byte is not included in SDL_AsyncIOOutcome's
+ * bytes_transferred value.
+ *
+ * This function will allocate the buffer to contain the file. It must be
+ * deallocated by calling SDL_free() on SDL_AsyncIOOutcome's buffer field
+ * after completion.
+ *
+ * An SDL_AsyncIOQueue must be specified. The newly-created task will be added
+ * to it when it completes its work.
+ *
+ * \param file the path to read all available data from.
+ * \param queue a queue to add the new SDL_AsyncIO to.
+ * \param userdata an app-defined pointer that will be provided with the task
+ *                 results.
+ * \returns true on success or false on failure; call SDL_GetError() for more
+ *          information.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_LoadFile_IO
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_LoadFileAsync(const char *file, SDL_AsyncIOQueue *queue, void *userdata);
+
+/* Ends C function definitions when using C++ */
+#ifdef __cplusplus
+}
+#endif
+#include <SDL3/SDL_close_code.h>
+
+#endif /* SDL_asyncio_h_ */