1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/LibOVR/Src/Kernel/OVR_Atomic.cpp	Wed Jan 14 06:51:16 2015 +0200
     1.3 @@ -0,0 +1,139 @@
     1.4 +/************************************************************************************
     1.5 +
     1.6 +Filename    :   OVR_Atomic.cpp
     1.7 +Content     :   Contains atomic operations and inline fastest locking
     1.8 +                functionality. Will contain #ifdefs for OS efficiency.
     1.9 +                Have non-thread-safe implementation if not available.
    1.10 +Created     :   September 19, 2012
    1.11 +Notes       : 
    1.12 +
    1.13 +Copyright   :   Copyright 2014 Oculus VR, LLC All Rights reserved.
    1.14 +
    1.15 +Licensed under the Oculus VR Rift SDK License Version 3.2 (the "License"); 
    1.16 +you may not use the Oculus VR Rift SDK except in compliance with the License, 
    1.17 +which is provided at the time of installation or download, or which 
    1.18 +otherwise accompanies this software in either electronic or hard copy form.
    1.19 +
    1.20 +You may obtain a copy of the License at
    1.21 +
    1.22 +http://www.oculusvr.com/licenses/LICENSE-3.2 
    1.23 +
    1.24 +Unless required by applicable law or agreed to in writing, the Oculus VR SDK 
    1.25 +distributed under the License is distributed on an "AS IS" BASIS,
    1.26 +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    1.27 +See the License for the specific language governing permissions and
    1.28 +limitations under the License.
    1.29 +
    1.30 +************************************************************************************/
    1.31 +
    1.32 +#include "OVR_Atomic.h"
    1.33 +#include "OVR_Allocator.h"
    1.34 +
    1.35 +#ifdef OVR_ENABLE_THREADS
    1.36 +
    1.37 +// Include Windows 8-Metro compatible Synchronization API
    1.38 +#if defined(OVR_OS_MS) && defined(NTDDI_WIN8) && (NTDDI_VERSION >= NTDDI_WIN8)
    1.39 +#include <synchapi.h>
    1.40 +#endif
    1.41 +
    1.42 +
    1.43 +namespace OVR {
    1.44 +
    1.45 +// ***** Windows Lock implementation
    1.46 +
    1.47 +#if defined(OVR_OS_MS)
    1.48 +
    1.49 +// ***** Standard Win32 Lock implementation
    1.50 +
    1.51 +// Constructors
    1.52 +Lock::Lock(unsigned spinCount)
    1.53 +{
    1.54 +    #if defined(NTDDI_WIN8) && (NTDDI_VERSION >= NTDDI_WIN8)
    1.55 +       // On Windows 8 we use InitializeCriticalSectionEx due to Metro-Compatibility
    1.56 +       InitializeCriticalSectionEx(&cs, (DWORD)spinCount,
    1.57 +                                   OVR_DEBUG_SELECT(NULL, CRITICAL_SECTION_NO_DEBUG_INFO));
    1.58 +    #else
    1.59 +        ::InitializeCriticalSectionAndSpinCount(&cs, (DWORD)spinCount); // This is available with WindowsXP+.
    1.60 +    #endif
    1.61 +}
    1.62 +
    1.63 +
    1.64 +Lock::~Lock()
    1.65 +{
    1.66 +    DeleteCriticalSection(&cs);
    1.67 +}
    1.68 +
    1.69 +
    1.70 +#endif
    1.71 +
    1.72 +
    1.73 +//-------------------------------------------------------------------------------------
    1.74 +// ***** SharedLock
    1.75 +
    1.76 +// This is a general purpose globally shared Lock implementation that should probably be
    1.77 +// moved to Kernel.
    1.78 +// May in theory busy spin-wait if we hit contention on first lock creation,
    1.79 +// but this shouldn't matter in practice since Lock* should be cached.
    1.80 +
    1.81 +
    1.82 +enum { LockInitMarker = 0xFFFFFFFF };
    1.83 +
    1.84 +Lock* SharedLock::GetLockAddRef()
    1.85 +{
    1.86 +    int oldUseCount;
    1.87 +
    1.88 +    do {
    1.89 +        oldUseCount = UseCount;
    1.90 +        if (oldUseCount == (int)LockInitMarker)
    1.91 +            continue;
    1.92 +
    1.93 +        if (oldUseCount == 0)
    1.94 +        {
    1.95 +            // Initialize marker
    1.96 +            if (AtomicOps<int>::CompareAndSet_Sync(&UseCount, 0, LockInitMarker))
    1.97 +            {
    1.98 +                Construct<Lock>(Buffer);
    1.99 +                do { }
   1.100 +                while (!AtomicOps<int>::CompareAndSet_Sync(&UseCount, LockInitMarker, 1));
   1.101 +                return toLock();
   1.102 +            }
   1.103 +            continue;
   1.104 +        }
   1.105 +
   1.106 +    } while (!AtomicOps<int>::CompareAndSet_NoSync(&UseCount, oldUseCount, oldUseCount + 1));
   1.107 +
   1.108 +    return toLock();
   1.109 +}
   1.110 +
   1.111 +void SharedLock::ReleaseLock(Lock* plock)
   1.112 +{
   1.113 +    OVR_UNUSED(plock);
   1.114 +    OVR_ASSERT(plock == toLock());
   1.115 +
   1.116 +    int oldUseCount;
   1.117 +
   1.118 +    do {
   1.119 +        oldUseCount = UseCount;
   1.120 +        OVR_ASSERT(oldUseCount != (int)LockInitMarker);
   1.121 +
   1.122 +        if (oldUseCount == 1)
   1.123 +        {
   1.124 +            // Initialize marker
   1.125 +            if (AtomicOps<int>::CompareAndSet_Sync(&UseCount, 1, LockInitMarker))
   1.126 +            {
   1.127 +                Destruct<Lock>(toLock());
   1.128 +
   1.129 +                do { }
   1.130 +                while (!AtomicOps<int>::CompareAndSet_Sync(&UseCount, LockInitMarker, 0));
   1.131 +
   1.132 +                return;
   1.133 +            }
   1.134 +            continue;
   1.135 +        }
   1.136 +
   1.137 +    } while (!AtomicOps<int>::CompareAndSet_NoSync(&UseCount, oldUseCount, oldUseCount - 1));
   1.138 +}
   1.139 +
   1.140 +} // OVR
   1.141 +
   1.142 +#endif // OVR_ENABLE_THREADS