My Thesis

How to use the Double Frame Buffer ...

 ///*
 for( Yin = 0; Yin < 480; Yin++)
  {
  for( Xin = 0; Xin < 640; Xin++)
   {
  // if( Yin == 0  Xin == 0  Xin == 639  Yin == 479)
  //  PalFrameBufferDBWrite(FBPtr, Xin, Yin, 0x00FFFF);
  
   PalFrameBufferDBWrite(FBPtr, Xin, Yin, 0xFFFFFF);
   }
  }
 //*/

 PalFrameBufferDBSwapBuffers(FBPtr);
 for( Yin = 0; Yin < 480; Yin++)
  {
  for( Xin = 0; Xin < 640; Xin++)
   {
   PalFrameBufferDBWrite(FBPtr, Xin, Yin, 0x00FF00);

   if( Yin == 0  Xin == 0  Xin == 639  Yin == 479)
   //if( Yin == 0 )
    PalFrameBufferDBWrite(FBPtr, Xin, Yin, 0xFFFFFF);
   }
  }

 PalFrameBufferDBSwapBuffers(FBPtr);

You must run a "dummy" loop (first two-for-loops) to sort of inititalize the frame buffer. The second framebuffer will work correctly. Failure to do so will cause undefined behaviour stuff.

/*
 * Abstract type of framebuffers
 */
typedef struct _PalFrameBufferDB PalFrameBufferDB;

/*
 * Double-buffered frame buffer API
 */
extern macro proc PalFrameBufferDBRun          (FrameBufferDBPtrPtr, 
                                                PL1RAMHandleCT0, 
                                                PL1RAMHandleCT1, 
                                                VideoOutHandleCT, 
                                                ClockRate);
extern macro proc PalFrameBufferDBReset        (FrameBufferDBPtr);
extern macro proc PalFrameBufferDBEnable       (FrameBufferDBPtr);
extern macro proc PalFrameBufferDBDisable      (FrameBufferDBPtr);
extern macro proc PalFrameBufferDBRead         (FrameBufferDBPtr, X, Y, 
                                                PixelPtr);
extern macro proc PalFrameBufferDBWrite        (FrameBufferDBPtr, X, Y, Pixel);
extern macro proc PalFrameBufferDBSwapBuffers  (FrameBufferDBPtr);

#endif /* __CELOXICA_PAL_FRAMEBUFFERDB_HCH__ */

Met up with Dr. Kenneth and DWT using the lifting scheme was expalined.