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authorSven Gothel <[email protected]>2014-06-19 17:03:28 +0200
committerSven Gothel <[email protected]>2014-06-19 17:03:28 +0200
commitd9a584844a60542519d813b5dc1a62428f14a0ae (patch)
tree942c10a5ebcd0aab65e9d6facb59778468f39d3b /LibOVR/Src/Kernel/OVR_Atomic.cpp
Add OculusSDK 0.3.2 Linux Source Code w/o Samples, docs or binaries (libs or tools)
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+/************************************************************************************
+
+Filename : OVR_Atomic.cpp
+Content : Contains atomic operations and inline fastest locking
+ functionality. Will contain #ifdefs for OS efficiency.
+ Have non-thread-safe implementation if not available.
+Created : September 19, 2012
+Notes :
+
+Copyright : Copyright 2014 Oculus VR, Inc. All Rights reserved.
+
+Licensed under the Oculus VR Rift SDK License Version 3.1 (the "License");
+you may not use the Oculus VR Rift SDK except in compliance with the License,
+which is provided at the time of installation or download, or which
+otherwise accompanies this software in either electronic or hard copy form.
+
+You may obtain a copy of the License at
+
+http://www.oculusvr.com/licenses/LICENSE-3.1
+
+Unless required by applicable law or agreed to in writing, the Oculus VR SDK
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+************************************************************************************/
+
+#include "OVR_Atomic.h"
+#include "OVR_Allocator.h"
+
+#ifdef OVR_ENABLE_THREADS
+
+// Include Windows 8-Metro compatible Synchronization API
+#if defined(OVR_OS_WIN32) && defined(NTDDI_WIN8) && (NTDDI_VERSION >= NTDDI_WIN8)
+#include <synchapi.h>
+#endif
+
+
+namespace OVR {
+
+// ***** Windows Lock implementation
+
+#if defined(OVR_OS_WIN32)
+
+// ***** Standard Win32 Lock implementation
+
+// Constructors
+Lock::Lock(unsigned spinCount)
+{
+#if defined(NTDDI_WIN8) && (NTDDI_VERSION >= NTDDI_WIN8)
+ // On Windows 8 we use InitializeCriticalSectionEx due to Metro-Compatibility
+ InitializeCriticalSectionEx(&cs, spinCount,
+ OVR_DEBUG_SELECT(NULL, CRITICAL_SECTION_NO_DEBUG_INFO));
+#else
+ // Spin count init critical section function prototype for Window NT
+ typedef BOOL (WINAPI *Function_InitializeCriticalSectionAndSpinCount)
+ (LPCRITICAL_SECTION lpCriticalSection, DWORD dwSpinCount);
+
+
+ // Try to load function dynamically so that we don't require NT
+ // On Windows NT we will use InitializeCriticalSectionAndSpinCount
+ static bool initTried = 0;
+ static Function_InitializeCriticalSectionAndSpinCount pInitFn = 0;
+
+ if (!initTried)
+ {
+ HMODULE hmodule = ::LoadLibrary(OVR_STR("kernel32.dll"));
+ pInitFn = (Function_InitializeCriticalSectionAndSpinCount)
+ ::GetProcAddress(hmodule, "InitializeCriticalSectionAndSpinCount");
+ initTried = true;
+ }
+
+ // Initialize the critical section
+ if (pInitFn)
+ pInitFn(&cs, spinCount);
+ else
+ ::InitializeCriticalSection(&cs);
+#endif
+
+}
+
+
+Lock::~Lock()
+{
+ DeleteCriticalSection(&cs);
+}
+
+
+#endif
+
+
+//-------------------------------------------------------------------------------------
+// ***** SharedLock
+
+// This is a general purpose globally shared Lock implementation that should probably be
+// moved to Kernel.
+// May in theory busy spin-wait if we hit contention on first lock creation,
+// but this shouldn't matter in practice since Lock* should be cached.
+
+
+enum { LockInitMarker = 0xFFFFFFFF };
+
+Lock* SharedLock::GetLockAddRef()
+{
+ int oldUseCount;
+
+ do {
+ oldUseCount = UseCount;
+ if (oldUseCount == LockInitMarker)
+ continue;
+
+ if (oldUseCount == 0)
+ {
+ // Initialize marker
+ if (AtomicOps<int>::CompareAndSet_Sync(&UseCount, 0, LockInitMarker))
+ {
+ Construct<Lock>(Buffer);
+ do { }
+ while (!AtomicOps<int>::CompareAndSet_Sync(&UseCount, LockInitMarker, 1));
+ return toLock();
+ }
+ continue;
+ }
+
+ } while (!AtomicOps<int>::CompareAndSet_NoSync(&UseCount, oldUseCount, oldUseCount + 1));
+
+ return toLock();
+}
+
+void SharedLock::ReleaseLock(Lock* plock)
+{
+ OVR_UNUSED(plock);
+ OVR_ASSERT(plock == toLock());
+
+ int oldUseCount;
+
+ do {
+ oldUseCount = UseCount;
+ OVR_ASSERT(oldUseCount != LockInitMarker);
+
+ if (oldUseCount == 1)
+ {
+ // Initialize marker
+ if (AtomicOps<int>::CompareAndSet_Sync(&UseCount, 1, LockInitMarker))
+ {
+ Destruct<Lock>(toLock());
+
+ do { }
+ while (!AtomicOps<int>::CompareAndSet_Sync(&UseCount, LockInitMarker, 0));
+
+ return;
+ }
+ continue;
+ }
+
+ } while (!AtomicOps<int>::CompareAndSet_NoSync(&UseCount, oldUseCount, oldUseCount - 1));
+}
+
+} // OVR
+
+#endif // OVR_ENABLE_THREADS