Update to SDL3

1 files changed, 1073 insertions, 0 deletions

diff --git a/src/contrib/SDL-3.2.20/include/SDL3/SDL_mutex.h b/src/contrib/SDL-3.2.20/include/SDL3/SDL_mutex.h
new file mode 100644
index 0000000..c88ec15
--- /dev/null
+++ b/src/contrib/SDL-3.2.20/include/SDL3/SDL_mutex.h
@@ -0,0 +1,1073 @@
+/*
+  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.
+*/
+
+#ifndef SDL_mutex_h_
+#define SDL_mutex_h_
+
+/**
+ * # CategoryMutex
+ *
+ * SDL offers several thread synchronization primitives. This document can't
+ * cover the complicated topic of thread safety, but reading up on what each
+ * of these primitives are, why they are useful, and how to correctly use them
+ * is vital to writing correct and safe multithreaded programs.
+ *
+ * - Mutexes: SDL_CreateMutex()
+ * - Read/Write locks: SDL_CreateRWLock()
+ * - Semaphores: SDL_CreateSemaphore()
+ * - Condition variables: SDL_CreateCondition()
+ *
+ * SDL also offers a datatype, SDL_InitState, which can be used to make sure
+ * only one thread initializes/deinitializes some resource that several
+ * threads might try to use for the first time simultaneously.
+ */
+
+#include <SDL3/SDL_stdinc.h>
+#include <SDL3/SDL_atomic.h>
+#include <SDL3/SDL_error.h>
+#include <SDL3/SDL_thread.h>
+
+#ifdef SDL_WIKI_DOCUMENTATION_SECTION
+
+/**
+ * Enable thread safety attributes, only with clang.
+ *
+ * The attributes can be safely erased when compiling with other compilers.
+ *
+ * To enable analysis, set these environment variables before running cmake:
+ *
+ * ```bash
+ * export CC=clang
+ * export CFLAGS="-DSDL_THREAD_SAFETY_ANALYSIS -Wthread-safety"
+ * ```
+ */
+#define SDL_THREAD_ANNOTATION_ATTRIBUTE__(x)   __attribute__((x))
+
+#elif defined(SDL_THREAD_SAFETY_ANALYSIS) && defined(__clang__) && (!defined(SWIG))
+#define SDL_THREAD_ANNOTATION_ATTRIBUTE__(x)   __attribute__((x))
+#else
+#define SDL_THREAD_ANNOTATION_ATTRIBUTE__(x)   /* no-op */
+#endif
+
+/**
+ * Wrapper around Clang thread safety analysis annotations.
+ *
+ * Please see https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h
+ *
+ * \since This macro is available since SDL 3.2.0.
+ */
+#define SDL_CAPABILITY(x) \
+  SDL_THREAD_ANNOTATION_ATTRIBUTE__(capability(x))
+
+/**
+ * Wrapper around Clang thread safety analysis annotations.
+ *
+ * Please see https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h
+ *
+ * \since This macro is available since SDL 3.2.0.
+ */
+#define SDL_SCOPED_CAPABILITY \
+  SDL_THREAD_ANNOTATION_ATTRIBUTE__(scoped_lockable)
+
+/**
+ * Wrapper around Clang thread safety analysis annotations.
+ *
+ * Please see https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h
+ *
+ * \since This macro is available since SDL 3.2.0.
+ */
+#define SDL_GUARDED_BY(x) \
+  SDL_THREAD_ANNOTATION_ATTRIBUTE__(guarded_by(x))
+
+/**
+ * Wrapper around Clang thread safety analysis annotations.
+ *
+ * Please see https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h
+ *
+ * \since This macro is available since SDL 3.2.0.
+ */
+#define SDL_PT_GUARDED_BY(x) \
+  SDL_THREAD_ANNOTATION_ATTRIBUTE__(pt_guarded_by(x))
+
+/**
+ * Wrapper around Clang thread safety analysis annotations.
+ *
+ * Please see https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h
+ *
+ * \since This macro is available since SDL 3.2.0.
+ */
+#define SDL_ACQUIRED_BEFORE(x) \
+  SDL_THREAD_ANNOTATION_ATTRIBUTE__(acquired_before(x))
+
+/**
+ * Wrapper around Clang thread safety analysis annotations.
+ *
+ * Please see https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h
+ *
+ * \since This macro is available since SDL 3.2.0.
+ */
+#define SDL_ACQUIRED_AFTER(x) \
+  SDL_THREAD_ANNOTATION_ATTRIBUTE__(acquired_after(x))
+
+/**
+ * Wrapper around Clang thread safety analysis annotations.
+ *
+ * Please see https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h
+ *
+ * \since This macro is available since SDL 3.2.0.
+ */
+#define SDL_REQUIRES(x) \
+  SDL_THREAD_ANNOTATION_ATTRIBUTE__(requires_capability(x))
+
+/**
+ * Wrapper around Clang thread safety analysis annotations.
+ *
+ * Please see https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h
+ *
+ * \since This macro is available since SDL 3.2.0.
+ */
+#define SDL_REQUIRES_SHARED(x) \
+  SDL_THREAD_ANNOTATION_ATTRIBUTE__(requires_shared_capability(x))
+
+/**
+ * Wrapper around Clang thread safety analysis annotations.
+ *
+ * Please see https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h
+ *
+ * \since This macro is available since SDL 3.2.0.
+ */
+#define SDL_ACQUIRE(x) \
+  SDL_THREAD_ANNOTATION_ATTRIBUTE__(acquire_capability(x))
+
+/**
+ * Wrapper around Clang thread safety analysis annotations.
+ *
+ * Please see https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h
+ *
+ * \since This macro is available since SDL 3.2.0.
+ */
+#define SDL_ACQUIRE_SHARED(x) \
+  SDL_THREAD_ANNOTATION_ATTRIBUTE__(acquire_shared_capability(x))
+
+/**
+ * Wrapper around Clang thread safety analysis annotations.
+ *
+ * Please see https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h
+ *
+ * \since This macro is available since SDL 3.2.0.
+ */
+#define SDL_RELEASE(x) \
+  SDL_THREAD_ANNOTATION_ATTRIBUTE__(release_capability(x))
+
+/**
+ * Wrapper around Clang thread safety analysis annotations.
+ *
+ * Please see https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h
+ *
+ * \since This macro is available since SDL 3.2.0.
+ */
+#define SDL_RELEASE_SHARED(x) \
+  SDL_THREAD_ANNOTATION_ATTRIBUTE__(release_shared_capability(x))
+
+/**
+ * Wrapper around Clang thread safety analysis annotations.
+ *
+ * Please see https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h
+ *
+ * \since This macro is available since SDL 3.2.0.
+ */
+#define SDL_RELEASE_GENERIC(x) \
+  SDL_THREAD_ANNOTATION_ATTRIBUTE__(release_generic_capability(x))
+
+/**
+ * Wrapper around Clang thread safety analysis annotations.
+ *
+ * Please see https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h
+ *
+ * \since This macro is available since SDL 3.2.0.
+ */
+#define SDL_TRY_ACQUIRE(x, y) \
+  SDL_THREAD_ANNOTATION_ATTRIBUTE__(try_acquire_capability(x, y))
+
+/**
+ * Wrapper around Clang thread safety analysis annotations.
+ *
+ * Please see https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h
+ *
+ * \since This macro is available since SDL 3.2.0.
+ */
+#define SDL_TRY_ACQUIRE_SHARED(x, y) \
+  SDL_THREAD_ANNOTATION_ATTRIBUTE__(try_acquire_shared_capability(x, y))
+
+/**
+ * Wrapper around Clang thread safety analysis annotations.
+ *
+ * Please see https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h
+ *
+ * \since This macro is available since SDL 3.2.0.
+ */
+#define SDL_EXCLUDES(x) \
+  SDL_THREAD_ANNOTATION_ATTRIBUTE__(locks_excluded(x))
+
+/**
+ * Wrapper around Clang thread safety analysis annotations.
+ *
+ * Please see https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h
+ *
+ * \since This macro is available since SDL 3.2.0.
+ */
+#define SDL_ASSERT_CAPABILITY(x) \
+  SDL_THREAD_ANNOTATION_ATTRIBUTE__(assert_capability(x))
+
+/**
+ * Wrapper around Clang thread safety analysis annotations.
+ *
+ * Please see https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h
+ *
+ * \since This macro is available since SDL 3.2.0.
+ */
+#define SDL_ASSERT_SHARED_CAPABILITY(x) \
+  SDL_THREAD_ANNOTATION_ATTRIBUTE__(assert_shared_capability(x))
+
+/**
+ * Wrapper around Clang thread safety analysis annotations.
+ *
+ * Please see https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h
+ *
+ * \since This macro is available since SDL 3.2.0.
+ */
+#define SDL_RETURN_CAPABILITY(x) \
+  SDL_THREAD_ANNOTATION_ATTRIBUTE__(lock_returned(x))
+
+/**
+ * Wrapper around Clang thread safety analysis annotations.
+ *
+ * Please see https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h
+ *
+ * \since This macro is available since SDL 3.2.0.
+ */
+#define SDL_NO_THREAD_SAFETY_ANALYSIS \
+  SDL_THREAD_ANNOTATION_ATTRIBUTE__(no_thread_safety_analysis)
+
+/******************************************************************************/
+
+
+#include <SDL3/SDL_begin_code.h>
+/* Set up for C function definitions, even when using C++ */
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ *  \name Mutex functions
+ */
+/* @{ */
+
+/**
+ * A means to serialize access to a resource between threads.
+ *
+ * Mutexes (short for "mutual exclusion") are a synchronization primitive that
+ * allows exactly one thread to proceed at a time.
+ *
+ * Wikipedia has a thorough explanation of the concept:
+ *
+ * https://en.wikipedia.org/wiki/Mutex
+ *
+ * \since This struct is available since SDL 3.2.0.
+ */
+typedef struct SDL_Mutex SDL_Mutex;
+
+/**
+ * Create a new mutex.
+ *
+ * All newly-created mutexes begin in the _unlocked_ state.
+ *
+ * Calls to SDL_LockMutex() will not return while the mutex is locked by
+ * another thread. See SDL_TryLockMutex() to attempt to lock without blocking.
+ *
+ * SDL mutexes are reentrant.
+ *
+ * \returns the initialized and unlocked mutex or NULL on failure; call
+ *          SDL_GetError() for more information.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_DestroyMutex
+ * \sa SDL_LockMutex
+ * \sa SDL_TryLockMutex
+ * \sa SDL_UnlockMutex
+ */
+extern SDL_DECLSPEC SDL_Mutex * SDLCALL SDL_CreateMutex(void);
+
+/**
+ * Lock the mutex.
+ *
+ * This will block until the mutex is available, which is to say it is in the
+ * unlocked state and the OS has chosen the caller as the next thread to lock
+ * it. Of all threads waiting to lock the mutex, only one may do so at a time.
+ *
+ * It is legal for the owning thread to lock an already-locked mutex. It must
+ * unlock it the same number of times before it is actually made available for
+ * other threads in the system (this is known as a "recursive mutex").
+ *
+ * This function does not fail; if mutex is NULL, it will return immediately
+ * having locked nothing. If the mutex is valid, this function will always
+ * block until it can lock the mutex, and return with it locked.
+ *
+ * \param mutex the mutex to lock.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_TryLockMutex
+ * \sa SDL_UnlockMutex
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_LockMutex(SDL_Mutex *mutex) SDL_ACQUIRE(mutex);
+
+/**
+ * Try to lock a mutex without blocking.
+ *
+ * This works just like SDL_LockMutex(), but if the mutex is not available,
+ * this function returns false immediately.
+ *
+ * This technique is useful if you need exclusive access to a resource but
+ * don't want to wait for it, and will return to it to try again later.
+ *
+ * This function returns true if passed a NULL mutex.
+ *
+ * \param mutex the mutex to try to lock.
+ * \returns true on success, false if the mutex would block.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_LockMutex
+ * \sa SDL_UnlockMutex
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_TryLockMutex(SDL_Mutex *mutex) SDL_TRY_ACQUIRE(0, mutex);
+
+/**
+ * Unlock the mutex.
+ *
+ * It is legal for the owning thread to lock an already-locked mutex. It must
+ * unlock it the same number of times before it is actually made available for
+ * other threads in the system (this is known as a "recursive mutex").
+ *
+ * It is illegal to unlock a mutex that has not been locked by the current
+ * thread, and doing so results in undefined behavior.
+ *
+ * \param mutex the mutex to unlock.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_LockMutex
+ * \sa SDL_TryLockMutex
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_UnlockMutex(SDL_Mutex *mutex) SDL_RELEASE(mutex);
+
+/**
+ * Destroy a mutex created with SDL_CreateMutex().
+ *
+ * This function must be called on any mutex that is no longer needed. Failure
+ * to destroy a mutex will result in a system memory or resource leak. While
+ * it is safe to destroy a mutex that is _unlocked_, it is not safe to attempt
+ * to destroy a locked mutex, and may result in undefined behavior depending
+ * on the platform.
+ *
+ * \param mutex the mutex to destroy.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_CreateMutex
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_DestroyMutex(SDL_Mutex *mutex);
+
+/* @} *//* Mutex functions */
+
+
+/**
+ *  \name Read/write lock functions
+ */
+/* @{ */
+
+/**
+ * A mutex that allows read-only threads to run in parallel.
+ *
+ * A rwlock is roughly the same concept as SDL_Mutex, but allows threads that
+ * request read-only access to all hold the lock at the same time. If a thread
+ * requests write access, it will block until all read-only threads have
+ * released the lock, and no one else can hold the thread (for reading or
+ * writing) at the same time as the writing thread.
+ *
+ * This can be more efficient in cases where several threads need to access
+ * data frequently, but changes to that data are rare.
+ *
+ * There are other rules that apply to rwlocks that don't apply to mutexes,
+ * about how threads are scheduled and when they can be recursively locked.
+ * These are documented in the other rwlock functions.
+ *
+ * \since This struct is available since SDL 3.2.0.
+ */
+typedef struct SDL_RWLock SDL_RWLock;
+
+/**
+ * Create a new read/write lock.
+ *
+ * A read/write lock is useful for situations where you have multiple threads
+ * trying to access a resource that is rarely updated. All threads requesting
+ * a read-only lock will be allowed to run in parallel; if a thread requests a
+ * write lock, it will be provided exclusive access. This makes it safe for
+ * multiple threads to use a resource at the same time if they promise not to
+ * change it, and when it has to be changed, the rwlock will serve as a
+ * gateway to make sure those changes can be made safely.
+ *
+ * In the right situation, a rwlock can be more efficient than a mutex, which
+ * only lets a single thread proceed at a time, even if it won't be modifying
+ * the data.
+ *
+ * All newly-created read/write locks begin in the _unlocked_ state.
+ *
+ * Calls to SDL_LockRWLockForReading() and SDL_LockRWLockForWriting will not
+ * return while the rwlock is locked _for writing_ by another thread. See
+ * SDL_TryLockRWLockForReading() and SDL_TryLockRWLockForWriting() to attempt
+ * to lock without blocking.
+ *
+ * SDL read/write locks are only recursive for read-only locks! They are not
+ * guaranteed to be fair, or provide access in a FIFO manner! They are not
+ * guaranteed to favor writers. You may not lock a rwlock for both read-only
+ * and write access at the same time from the same thread (so you can't
+ * promote your read-only lock to a write lock without unlocking first).
+ *
+ * \returns the initialized and unlocked read/write lock or NULL on failure;
+ *          call SDL_GetError() for more information.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_DestroyRWLock
+ * \sa SDL_LockRWLockForReading
+ * \sa SDL_LockRWLockForWriting
+ * \sa SDL_TryLockRWLockForReading
+ * \sa SDL_TryLockRWLockForWriting
+ * \sa SDL_UnlockRWLock
+ */
+extern SDL_DECLSPEC SDL_RWLock * SDLCALL SDL_CreateRWLock(void);
+
+/**
+ * Lock the read/write lock for _read only_ operations.
+ *
+ * This will block until the rwlock is available, which is to say it is not
+ * locked for writing by any other thread. Of all threads waiting to lock the
+ * rwlock, all may do so at the same time as long as they are requesting
+ * read-only access; if a thread wants to lock for writing, only one may do so
+ * at a time, and no other threads, read-only or not, may hold the lock at the
+ * same time.
+ *
+ * It is legal for the owning thread to lock an already-locked rwlock for
+ * reading. It must unlock it the same number of times before it is actually
+ * made available for other threads in the system (this is known as a
+ * "recursive rwlock").
+ *
+ * Note that locking for writing is not recursive (this is only available to
+ * read-only locks).
+ *
+ * It is illegal to request a read-only lock from a thread that already holds
+ * the write lock. Doing so results in undefined behavior. Unlock the write
+ * lock before requesting a read-only lock. (But, of course, if you have the
+ * write lock, you don't need further locks to read in any case.)
+ *
+ * This function does not fail; if rwlock is NULL, it will return immediately
+ * having locked nothing. If the rwlock is valid, this function will always
+ * block until it can lock the mutex, and return with it locked.
+ *
+ * \param rwlock the read/write lock to lock.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_LockRWLockForWriting
+ * \sa SDL_TryLockRWLockForReading
+ * \sa SDL_UnlockRWLock
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_LockRWLockForReading(SDL_RWLock *rwlock) SDL_ACQUIRE_SHARED(rwlock);
+
+/**
+ * Lock the read/write lock for _write_ operations.
+ *
+ * This will block until the rwlock is available, which is to say it is not
+ * locked for reading or writing by any other thread. Only one thread may hold
+ * the lock when it requests write access; all other threads, whether they
+ * also want to write or only want read-only access, must wait until the
+ * writer thread has released the lock.
+ *
+ * It is illegal for the owning thread to lock an already-locked rwlock for
+ * writing (read-only may be locked recursively, writing can not). Doing so
+ * results in undefined behavior.
+ *
+ * It is illegal to request a write lock from a thread that already holds a
+ * read-only lock. Doing so results in undefined behavior. Unlock the
+ * read-only lock before requesting a write lock.
+ *
+ * This function does not fail; if rwlock is NULL, it will return immediately
+ * having locked nothing. If the rwlock is valid, this function will always
+ * block until it can lock the mutex, and return with it locked.
+ *
+ * \param rwlock the read/write lock to lock.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_LockRWLockForReading
+ * \sa SDL_TryLockRWLockForWriting
+ * \sa SDL_UnlockRWLock
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_LockRWLockForWriting(SDL_RWLock *rwlock) SDL_ACQUIRE(rwlock);
+
+/**
+ * Try to lock a read/write lock _for reading_ without blocking.
+ *
+ * This works just like SDL_LockRWLockForReading(), but if the rwlock is not
+ * available, then this function returns false immediately.
+ *
+ * This technique is useful if you need access to a resource but don't want to
+ * wait for it, and will return to it to try again later.
+ *
+ * Trying to lock for read-only access can succeed if other threads are
+ * holding read-only locks, as this won't prevent access.
+ *
+ * This function returns true if passed a NULL rwlock.
+ *
+ * \param rwlock the rwlock to try to lock.
+ * \returns true on success, false if the lock would block.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_LockRWLockForReading
+ * \sa SDL_TryLockRWLockForWriting
+ * \sa SDL_UnlockRWLock
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_TryLockRWLockForReading(SDL_RWLock *rwlock) SDL_TRY_ACQUIRE_SHARED(0, rwlock);
+
+/**
+ * Try to lock a read/write lock _for writing_ without blocking.
+ *
+ * This works just like SDL_LockRWLockForWriting(), but if the rwlock is not
+ * available, then this function returns false immediately.
+ *
+ * This technique is useful if you need exclusive access to a resource but
+ * don't want to wait for it, and will return to it to try again later.
+ *
+ * It is illegal for the owning thread to lock an already-locked rwlock for
+ * writing (read-only may be locked recursively, writing can not). Doing so
+ * results in undefined behavior.
+ *
+ * It is illegal to request a write lock from a thread that already holds a
+ * read-only lock. Doing so results in undefined behavior. Unlock the
+ * read-only lock before requesting a write lock.
+ *
+ * This function returns true if passed a NULL rwlock.
+ *
+ * \param rwlock the rwlock to try to lock.
+ * \returns true on success, false if the lock would block.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_LockRWLockForWriting
+ * \sa SDL_TryLockRWLockForReading
+ * \sa SDL_UnlockRWLock
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_TryLockRWLockForWriting(SDL_RWLock *rwlock) SDL_TRY_ACQUIRE(0, rwlock);
+
+/**
+ * Unlock the read/write lock.
+ *
+ * Use this function to unlock the rwlock, whether it was locked for read-only
+ * or write operations.
+ *
+ * It is legal for the owning thread to lock an already-locked read-only lock.
+ * It must unlock it the same number of times before it is actually made
+ * available for other threads in the system (this is known as a "recursive
+ * rwlock").
+ *
+ * It is illegal to unlock a rwlock that has not been locked by the current
+ * thread, and doing so results in undefined behavior.
+ *
+ * \param rwlock the rwlock to unlock.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_LockRWLockForReading
+ * \sa SDL_LockRWLockForWriting
+ * \sa SDL_TryLockRWLockForReading
+ * \sa SDL_TryLockRWLockForWriting
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_UnlockRWLock(SDL_RWLock *rwlock) SDL_RELEASE_GENERIC(rwlock);
+
+/**
+ * Destroy a read/write lock created with SDL_CreateRWLock().
+ *
+ * This function must be called on any read/write lock that is no longer
+ * needed. Failure to destroy a rwlock will result in a system memory or
+ * resource leak. While it is safe to destroy a rwlock that is _unlocked_, it
+ * is not safe to attempt to destroy a locked rwlock, and may result in
+ * undefined behavior depending on the platform.
+ *
+ * \param rwlock the rwlock to destroy.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_CreateRWLock
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_DestroyRWLock(SDL_RWLock *rwlock);
+
+/* @} *//* Read/write lock functions */
+
+
+/**
+ *  \name Semaphore functions
+ */
+/* @{ */
+
+/**
+ * A means to manage access to a resource, by count, between threads.
+ *
+ * Semaphores (specifically, "counting semaphores"), let X number of threads
+ * request access at the same time, each thread granted access decrementing a
+ * counter. When the counter reaches zero, future requests block until a prior
+ * thread releases their request, incrementing the counter again.
+ *
+ * Wikipedia has a thorough explanation of the concept:
+ *
+ * https://en.wikipedia.org/wiki/Semaphore_(programming)
+ *
+ * \since This struct is available since SDL 3.2.0.
+ */
+typedef struct SDL_Semaphore SDL_Semaphore;
+
+/**
+ * Create a semaphore.
+ *
+ * This function creates a new semaphore and initializes it with the value
+ * `initial_value`. Each wait operation on the semaphore will atomically
+ * decrement the semaphore value and potentially block if the semaphore value
+ * is 0. Each post operation will atomically increment the semaphore value and
+ * wake waiting threads and allow them to retry the wait operation.
+ *
+ * \param initial_value the starting value of the semaphore.
+ * \returns a new semaphore or NULL on failure; call SDL_GetError() for more
+ *          information.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_DestroySemaphore
+ * \sa SDL_SignalSemaphore
+ * \sa SDL_TryWaitSemaphore
+ * \sa SDL_GetSemaphoreValue
+ * \sa SDL_WaitSemaphore
+ * \sa SDL_WaitSemaphoreTimeout
+ */
+extern SDL_DECLSPEC SDL_Semaphore * SDLCALL SDL_CreateSemaphore(Uint32 initial_value);
+
+/**
+ * Destroy a semaphore.
+ *
+ * It is not safe to destroy a semaphore if there are threads currently
+ * waiting on it.
+ *
+ * \param sem the semaphore to destroy.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_CreateSemaphore
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_DestroySemaphore(SDL_Semaphore *sem);
+
+/**
+ * Wait until a semaphore has a positive value and then decrements it.
+ *
+ * This function suspends the calling thread until the semaphore pointed to by
+ * `sem` has a positive value, and then atomically decrement the semaphore
+ * value.
+ *
+ * This function is the equivalent of calling SDL_WaitSemaphoreTimeout() with
+ * a time length of -1.
+ *
+ * \param sem the semaphore wait on.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_SignalSemaphore
+ * \sa SDL_TryWaitSemaphore
+ * \sa SDL_WaitSemaphoreTimeout
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_WaitSemaphore(SDL_Semaphore *sem);
+
+/**
+ * See if a semaphore has a positive value and decrement it if it does.
+ *
+ * This function checks to see if the semaphore pointed to by `sem` has a
+ * positive value and atomically decrements the semaphore value if it does. If
+ * the semaphore doesn't have a positive value, the function immediately
+ * returns false.
+ *
+ * \param sem the semaphore to wait on.
+ * \returns true if the wait succeeds, false if the wait would block.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_SignalSemaphore
+ * \sa SDL_WaitSemaphore
+ * \sa SDL_WaitSemaphoreTimeout
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_TryWaitSemaphore(SDL_Semaphore *sem);
+
+/**
+ * Wait until a semaphore has a positive value and then decrements it.
+ *
+ * This function suspends the calling thread until either the semaphore
+ * pointed to by `sem` has a positive value or the specified time has elapsed.
+ * If the call is successful it will atomically decrement the semaphore value.
+ *
+ * \param sem the semaphore to wait on.
+ * \param timeoutMS the length of the timeout, in milliseconds, or -1 to wait
+ *                  indefinitely.
+ * \returns true if the wait succeeds or false if the wait times out.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_SignalSemaphore
+ * \sa SDL_TryWaitSemaphore
+ * \sa SDL_WaitSemaphore
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_WaitSemaphoreTimeout(SDL_Semaphore *sem, Sint32 timeoutMS);
+
+/**
+ * Atomically increment a semaphore's value and wake waiting threads.
+ *
+ * \param sem the semaphore to increment.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_TryWaitSemaphore
+ * \sa SDL_WaitSemaphore
+ * \sa SDL_WaitSemaphoreTimeout
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_SignalSemaphore(SDL_Semaphore *sem);
+
+/**
+ * Get the current value of a semaphore.
+ *
+ * \param sem the semaphore to query.
+ * \returns the current value of the semaphore.
+ *
+ * \since This function is available since SDL 3.2.0.
+ */
+extern SDL_DECLSPEC Uint32 SDLCALL SDL_GetSemaphoreValue(SDL_Semaphore *sem);
+
+/* @} *//* Semaphore functions */
+
+
+/**
+ *  \name Condition variable functions
+ */
+/* @{ */
+
+/**
+ * A means to block multiple threads until a condition is satisfied.
+ *
+ * Condition variables, paired with an SDL_Mutex, let an app halt multiple
+ * threads until a condition has occurred, at which time the app can release
+ * one or all waiting threads.
+ *
+ * Wikipedia has a thorough explanation of the concept:
+ *
+ * https://en.wikipedia.org/wiki/Condition_variable
+ *
+ * \since This struct is available since SDL 3.2.0.
+ */
+typedef struct SDL_Condition SDL_Condition;
+
+/**
+ * Create a condition variable.
+ *
+ * \returns a new condition variable or NULL on failure; call SDL_GetError()
+ *          for more information.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_BroadcastCondition
+ * \sa SDL_SignalCondition
+ * \sa SDL_WaitCondition
+ * \sa SDL_WaitConditionTimeout
+ * \sa SDL_DestroyCondition
+ */
+extern SDL_DECLSPEC SDL_Condition * SDLCALL SDL_CreateCondition(void);
+
+/**
+ * Destroy a condition variable.
+ *
+ * \param cond the condition variable to destroy.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_CreateCondition
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_DestroyCondition(SDL_Condition *cond);
+
+/**
+ * Restart one of the threads that are waiting on the condition variable.
+ *
+ * \param cond the condition variable 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_BroadcastCondition
+ * \sa SDL_WaitCondition
+ * \sa SDL_WaitConditionTimeout
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_SignalCondition(SDL_Condition *cond);
+
+/**
+ * Restart all threads that are waiting on the condition variable.
+ *
+ * \param cond the condition variable 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_SignalCondition
+ * \sa SDL_WaitCondition
+ * \sa SDL_WaitConditionTimeout
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_BroadcastCondition(SDL_Condition *cond);
+
+/**
+ * Wait until a condition variable is signaled.
+ *
+ * This function unlocks the specified `mutex` and waits for another thread to
+ * call SDL_SignalCondition() or SDL_BroadcastCondition() on the condition
+ * variable `cond`. Once the condition variable is signaled, the mutex is
+ * re-locked and the function returns.
+ *
+ * The mutex must be locked before calling this function. Locking the mutex
+ * recursively (more than once) is not supported and leads to undefined
+ * behavior.
+ *
+ * This function is the equivalent of calling SDL_WaitConditionTimeout() with
+ * a time length of -1.
+ *
+ * \param cond the condition variable to wait on.
+ * \param mutex the mutex used to coordinate thread access.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_BroadcastCondition
+ * \sa SDL_SignalCondition
+ * \sa SDL_WaitConditionTimeout
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_WaitCondition(SDL_Condition *cond, SDL_Mutex *mutex);
+
+/**
+ * Wait until a condition variable is signaled or a certain time has passed.
+ *
+ * This function unlocks the specified `mutex` and waits for another thread to
+ * call SDL_SignalCondition() or SDL_BroadcastCondition() on the condition
+ * variable `cond`, or for the specified time to elapse. Once the condition
+ * variable is signaled or the time elapsed, the mutex is re-locked and the
+ * function returns.
+ *
+ * The mutex must be locked before calling this function. Locking the mutex
+ * recursively (more than once) is not supported and leads to undefined
+ * behavior.
+ *
+ * \param cond the condition variable to wait on.
+ * \param mutex the mutex used to coordinate thread access.
+ * \param timeoutMS the maximum time to wait, in milliseconds, or -1 to wait
+ *                  indefinitely.
+ * \returns true if the condition variable is signaled, false if the condition
+ *          is not signaled in the allotted time.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_BroadcastCondition
+ * \sa SDL_SignalCondition
+ * \sa SDL_WaitCondition
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_WaitConditionTimeout(SDL_Condition *cond,
+                                                SDL_Mutex *mutex, Sint32 timeoutMS);
+
+/* @} *//* Condition variable functions */
+
+/**
+ *  \name Thread-safe initialization state functions
+ */
+/* @{ */
+
+/**
+ * The current status of an SDL_InitState structure.
+ *
+ * \since This enum is available since SDL 3.2.0.
+ */
+typedef enum SDL_InitStatus
+{
+    SDL_INIT_STATUS_UNINITIALIZED,
+    SDL_INIT_STATUS_INITIALIZING,
+    SDL_INIT_STATUS_INITIALIZED,
+    SDL_INIT_STATUS_UNINITIALIZING
+} SDL_InitStatus;
+
+/**
+ * A structure used for thread-safe initialization and shutdown.
+ *
+ * Here is an example of using this:
+ *
+ * ```c
+ *    static SDL_AtomicInitState init;
+ *
+ *    bool InitSystem(void)
+ *    {
+ *        if (!SDL_ShouldInit(&init)) {
+ *            // The system is initialized
+ *            return true;
+ *        }
+ *
+ *        // At this point, you should not leave this function without calling SDL_SetInitialized()
+ *
+ *        bool initialized = DoInitTasks();
+ *        SDL_SetInitialized(&init, initialized);
+ *        return initialized;
+ *    }
+ *
+ *    bool UseSubsystem(void)
+ *    {
+ *        if (SDL_ShouldInit(&init)) {
+ *            // Error, the subsystem isn't initialized
+ *            SDL_SetInitialized(&init, false);
+ *            return false;
+ *        }
+ *
+ *        // Do work using the initialized subsystem
+ *
+ *        return true;
+ *    }
+ *
+ *    void QuitSystem(void)
+ *    {
+ *        if (!SDL_ShouldQuit(&init)) {
+ *            // The system is not initialized
+ *            return;
+ *        }
+ *
+ *        // At this point, you should not leave this function without calling SDL_SetInitialized()
+ *
+ *        DoQuitTasks();
+ *        SDL_SetInitialized(&init, false);
+ *    }
+ * ```
+ *
+ * Note that this doesn't protect any resources created during initialization,
+ * or guarantee that nobody is using those resources during cleanup. You
+ * should use other mechanisms to protect those, if that's a concern for your
+ * code.
+ *
+ * \since This struct is available since SDL 3.2.0.
+ */
+typedef struct SDL_InitState
+{
+    SDL_AtomicInt status;
+    SDL_ThreadID thread;
+    void *reserved;
+} SDL_InitState;
+
+/**
+ * Return whether initialization should be done.
+ *
+ * This function checks the passed in state and if initialization should be
+ * done, sets the status to `SDL_INIT_STATUS_INITIALIZING` and returns true.
+ * If another thread is already modifying this state, it will wait until
+ * that's done before returning.
+ *
+ * If this function returns true, the calling code must call
+ * SDL_SetInitialized() to complete the initialization.
+ *
+ * \param state the initialization state to check.
+ * \returns true if initialization needs to be done, 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_SetInitialized
+ * \sa SDL_ShouldQuit
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_ShouldInit(SDL_InitState *state);
+
+/**
+ * Return whether cleanup should be done.
+ *
+ * This function checks the passed in state and if cleanup should be done,
+ * sets the status to `SDL_INIT_STATUS_UNINITIALIZING` and returns true.
+ *
+ * If this function returns true, the calling code must call
+ * SDL_SetInitialized() to complete the cleanup.
+ *
+ * \param state the initialization state to check.
+ * \returns true if cleanup needs to be done, 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_SetInitialized
+ * \sa SDL_ShouldInit
+ */
+extern SDL_DECLSPEC bool SDLCALL SDL_ShouldQuit(SDL_InitState *state);
+
+/**
+ * Finish an initialization state transition.
+ *
+ * This function sets the status of the passed in state to
+ * `SDL_INIT_STATUS_INITIALIZED` or `SDL_INIT_STATUS_UNINITIALIZED` and allows
+ * any threads waiting for the status to proceed.
+ *
+ * \param state the initialization state to check.
+ * \param initialized the new initialization state.
+ *
+ * \threadsafety It is safe to call this function from any thread.
+ *
+ * \since This function is available since SDL 3.2.0.
+ *
+ * \sa SDL_ShouldInit
+ * \sa SDL_ShouldQuit
+ */
+extern SDL_DECLSPEC void SDLCALL SDL_SetInitialized(SDL_InitState *state, bool initialized);
+
+/* @} *//* Thread-safe initialization state functions */
+
+/* Ends C function definitions when using C++ */
+#ifdef __cplusplus
+}
+#endif
+#include <SDL3/SDL_close_code.h>
+
+#endif /* SDL_mutex_h_ */