CrystalSpace

Public API Reference

cstool/framedataholder.h

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00001 /*
00002     Copyright (C) 2004 by Jorrit Tyberghein
00003               (C) 2004 by Frank Richter
00004 
00005     This library is free software; you can redistribute it and/or
00006     modify it under the terms of the GNU Library General Public
00007     License as published by the Free Software Foundation; either
00008     version 2 of the License, or (at your option) any later version.
00009 
00010     This library is distributed in the hope that it will be useful,
00011     but WITHOUT ANY WARRANTY; without even the implied warranty of
00012     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013     Library General Public License for more details.
00014 
00015     You should have received a copy of the GNU Library General Public
00016     License along with this library; if not, write to the Free
00017     Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
00018 */
00019 
00020 #ifndef __CS_CSTOOL_FRAMEDATAHOLDER_H__
00021 #define __CS_CSTOOL_FRAMEDATAHOLDER_H__
00022 
00028 #include "csutil/array.h"
00029 
00036 template <class T>
00037 class csFrameDataHolder
00038 {
00040   struct FrameData
00041   {
00043     uint lastFrame;
00045     T data;
00046   };
00048   csArray<FrameData> data;
00050   size_t lastData;
00052   uint nextShrink;
00054   uint lastFrame;
00056   uint clearReq;
00057 
00059   void NewFrame()
00060   {
00061     if (clearReq != (uint)~0)
00062     {
00063       data.DeleteAll();
00064       clearReq = (uint)~0;
00065     }
00066     // Try to shrink the cache to a size that reflects what's needed
00067     if (lastFrame > nextShrink)
00068     {
00069       /* lastData is reset every frame, so it gives a good indicator
00070        * on how much has been used the last frame */
00071       data.Truncate (lastData+1);
00072       data.ShrinkBestFit ();
00073       nextShrink = (uint)~0;
00074     }
00075     else if (lastData+1 < data.GetSize())
00076     {
00077       // Last frame we used less cache than available.
00078       // "Schedule" a shrink in the future.
00079       nextShrink = lastFrame + 5;
00080     }
00081     lastData = 0;
00082   }
00083 public:
00084   csFrameDataHolder () : lastData(0), nextShrink((uint)~0),
00085         lastFrame((uint)~0), clearReq((uint)~0)
00086   { }
00087   ~csFrameDataHolder () { }
00088 
00096   T& GetUnusedData (bool& created, uint frameNumber)
00097   {
00098     if (lastFrame != frameNumber)
00099     {
00100       NewFrame();
00101       lastFrame = frameNumber;
00102     }
00103     created = false;
00104     if ((data.GetSize() == 0) || (data[lastData].lastFrame == frameNumber))
00105     {
00106       size_t startPoint = lastData;
00107       //check the list
00108       if (data.GetSize() > 0)
00109       {
00110         do
00111         {
00112           if (data[lastData].lastFrame != frameNumber)
00113             break;
00114           lastData++;
00115           if (lastData >= data.GetSize()) lastData = 0;
00116         }
00117         while (lastData != startPoint);
00118       }
00119       if (lastData == startPoint)
00120       {
00121         data.SetSize ((lastData = data.GetSize ()) + 1);
00122         created = true;
00123       }
00124     }
00125   
00126     FrameData& frameData = data[lastData];
00127     frameData.lastFrame = frameNumber;
00128     return frameData.data;
00129   }
00130   
00140   void Clear (bool instaClear = false)
00141   {
00142     if (instaClear)
00143       data.DeleteAll();
00144     else
00145       // Don't clear just yet, rather, clear when we enter the next frame.
00146       clearReq = lastFrame;
00147   }
00148 };
00149 
00150 #endif // __CS_CSTOOL_FRAMEDATAHOLDER_H__

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