Engine directory for ticket #1

Engine/source/platformWin32/winTimer.cpp

@@ -0,0 +1,88 @@
+//-----------------------------------------------------------------------------
+// Copyright (c) 2012 GarageGames, LLC
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to
+// deal in the Software without restriction, including without limitation the
+// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+// sell copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+// IN THE SOFTWARE.
+//-----------------------------------------------------------------------------
+
+// Grab the win32 headers so we can access QPC
+#define WIN32_LEAN_AND_MEAN
+#include <Windows.h>
+
+#include "platform/platformTimer.h"
+#include "math/mMath.h"
+
+class Win32Timer : public PlatformTimer
+{
+private:
+   U32 mTickCountCurrent;
+   U32 mTickCountNext;
+   S64 mPerfCountCurrent;
+   S64 mPerfCountNext;
+   S64 mFrequency;
+   F64 mPerfCountRemainderCurrent;
+   F64 mPerfCountRemainderNext;
+   bool mUsingPerfCounter;
+public:
+
+   Win32Timer()
+   {
+      mPerfCountRemainderCurrent = 0.0f;
+
+      // Attempt to use QPC for high res timing, otherwise fallback to GTC.
+      mUsingPerfCounter = QueryPerformanceFrequency((LARGE_INTEGER *) &mFrequency);
+      if(mUsingPerfCounter)
+         mUsingPerfCounter = QueryPerformanceCounter((LARGE_INTEGER *) &mPerfCountCurrent);
+      if(!mUsingPerfCounter)
+         mTickCountCurrent = GetTickCount();
+   }
+
+   const S32 getElapsedMs()
+   {
+      if(mUsingPerfCounter)
+      {
+         // Use QPC, update remainders so we don't leak time, and return the elapsed time.
+         QueryPerformanceCounter( (LARGE_INTEGER *) &mPerfCountNext);
+         F64 elapsedF64 = (1000.0 * F64(mPerfCountNext - mPerfCountCurrent) / F64(mFrequency));
+         elapsedF64 += mPerfCountRemainderCurrent;
+         U32 elapsed = (U32)mFloor(elapsedF64);
+         mPerfCountRemainderNext = elapsedF64 - F64(elapsed);
+
+         return elapsed;
+      }
+      else
+      {
+         // Do something naive with GTC.
+         mTickCountNext = GetTickCount();
+         return mTickCountNext - mTickCountCurrent;
+      }
+   }
+
+   void reset()
+   {
+      // Do some simple copying to reset the timer to 0.
+      mTickCountCurrent = mTickCountNext;
+      mPerfCountCurrent = mPerfCountNext;
+      mPerfCountRemainderCurrent = mPerfCountRemainderNext;
+   }
+};
+
+PlatformTimer *PlatformTimer::create()
+{
+   return new Win32Timer();
+}