Added a README file regarding WinRT support

To note, this file is currently formatted with CRLF line endings, rather than LF, to allow the file to be viewed with Notepad.
2025-09-29 14:38:29 +00:00 · 2014-04-09 21:29:19 -04:00
commit 3dcb451f85
1838 changed files with 474982 additions and 0 deletions
--- a/src/atomic/SDL_spinlock.c
+++ b/src/atomic/SDL_spinlock.c
@@ -0,0 +1,126 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2014 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"
+
+#if defined(__WIN32__) || defined(__WINRT__)
+#include "../core/windows/SDL_windows.h"
+#endif
+
+#include "SDL_atomic.h"
+#include "SDL_mutex.h"
+#include "SDL_timer.h"
+
+
+/* This function is where all the magic happens... */
+SDL_bool
+SDL_AtomicTryLock(SDL_SpinLock *lock)
+{
+#if SDL_ATOMIC_DISABLED
+    /* Terrible terrible damage */
+    static SDL_mutex *_spinlock_mutex;
+
+    if (!_spinlock_mutex) {
+        /* Race condition on first lock... */
+        _spinlock_mutex = SDL_CreateMutex();
+    }
+    SDL_LockMutex(_spinlock_mutex);
+    if (*lock == 0) {
+        *lock = 1;
+        SDL_UnlockMutex(_spinlock_mutex);
+        return SDL_TRUE;
+    } else {
+        SDL_UnlockMutex(_spinlock_mutex);
+        return SDL_FALSE;
+    }
+
+#elif defined(_MSC_VER)
+    SDL_COMPILE_TIME_ASSERT(locksize, sizeof(*lock) == sizeof(long));
+    return (InterlockedExchange((long*)lock, 1) == 0);
+
+#elif HAVE_GCC_ATOMICS || HAVE_GCC_SYNC_LOCK_TEST_AND_SET
+    return (__sync_lock_test_and_set(lock, 1) == 0);
+
+#elif defined(__GNUC__) && defined(__arm__) && \
+        (defined(__ARM_ARCH_4__) || defined(__ARM_ARCH_4T__) || \
+         defined(__ARM_ARCH_5__) || defined(__ARM_ARCH_5TE__) || \
+         defined(__ARM_ARCH_5TEJ__))
+    int result;
+    __asm__ __volatile__ (
+        "swp %0, %1, [%2]\n"
+        : "=&r,&r" (result) : "r,0" (1), "r,r" (lock) : "memory");
+    return (result == 0);
+
+#elif defined(__GNUC__) && defined(__arm__)
+    int result;
+    __asm__ __volatile__ (
+        "ldrex %0, [%2]\nteq   %0, #0\nstrexeq %0, %1, [%2]"
+        : "=&r" (result) : "r" (1), "r" (lock) : "cc", "memory");
+    return (result == 0);
+
+#elif defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
+    int result;
+    __asm__ __volatile__(
+        "lock ; xchgl %0, (%1)\n"
+        : "=r" (result) : "r" (lock), "0" (1) : "cc", "memory");
+    return (result == 0);
+
+#elif defined(__MACOSX__) || defined(__IPHONEOS__)
+    /* Maybe used for PowerPC, but the Intel asm or gcc atomics are favored. */
+    return OSAtomicCompareAndSwap32Barrier(0, 1, lock);
+
+#elif HAVE_PTHREAD_SPINLOCK
+    /* pthread instructions */
+    return (pthread_spin_trylock(lock) == 0);
+
+#else
+#error Please implement for your platform.
+    return SDL_FALSE;
+#endif
+}
+
+void
+SDL_AtomicLock(SDL_SpinLock *lock)
+{
+    /* FIXME: Should we have an eventual timeout? */
+    while (!SDL_AtomicTryLock(lock)) {
+        SDL_Delay(0);
+    }
+}
+
+void
+SDL_AtomicUnlock(SDL_SpinLock *lock)
+{
+#if defined(_MSC_VER)
+    _ReadWriteBarrier();
+    *lock = 0;
+
+#elif HAVE_GCC_ATOMICS || HAVE_GCC_SYNC_LOCK_TEST_AND_SET
+    __sync_lock_release(lock);
+
+#elif HAVE_PTHREAD_SPINLOCK
+    pthread_spin_unlock(lock);
+
+#else
+    *lock = 0;
+#endif
+}
+
+/* vi: set ts=4 sw=4 expandtab: */