--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/atomic/SDL_spinlock.c	Sat Jan 15 12:41:59 2011 -0800
@@ -0,0 +1,99 @@
+/*
+  SDL - Simple DirectMedia Layer
+  Copyright (C) 1997-2010 Sam Lantinga
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+
+  Sam Lantinga
+  slouken@libsdl.org
+*/
+#include "SDL_stdinc.h"
+
+#include "SDL_atomic.h"
+#include "SDL_timer.h"
+
+#if defined(__WIN32__)
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+
+#elif defined(__MACOSX__)
+#include <libkern/OSAtomic.h>
+
+#endif
+
+
+/* This function is where all the magic happens... */
+SDL_bool
+SDL_AtomicTryLock(SDL_SpinLock *lock)
+{
+#if defined(__WIN32__)
+    return (InterlockedExchange(lock, 1) == 0);
+
+#elif defined(__MACOSX__)
+    return OSAtomicCompareAndSwap32Barrier(0, 1, lock);
+
+#elif defined(__GNUC__)
+#if defined(__arm__)
+#ifdef __ARM_ARCH_5__
+    int result;
+    __asm__ __volatile__ (
+        "swp %0, %1, [%2]\n"
+        : "=&r,&r" (result) : "r,0" (1), "r,r" (lock) : "memory");
+    return (result == 0);
+#else
+    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);
+#endif
+#else
+    return (__sync_lock_test_and_set(lock, 1) == 0);
+#endif
+
+#else
+    /* Need CPU instructions for spinlock here! */
+    __need_spinlock_implementation__
+#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(__WIN32__)
+    *lock = 0;
+
+#elif defined(__MACOSX__)
+    *lock = 0;
+
+#elif defined(__GNUC__) && !defined(__arm__)
+    __sync_lock_release(lock);
+
+#else
+    /* Assuming memory barrier in lock and integral assignment operation */
+    *lock = 0;
+#endif
+}
+
+/* vi: set ts=4 sw=4 expandtab: */