/***************************************************************************
                          fps.c  -  description
                             -------------------
    begin                : Sun Oct 28 2001
    copyright            : (C) 2001 by Pete Bernert
    email                : BlackDove@addcom.de
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version. See also the license.txt file for *
 *   additional informations.                                              *
 *                                                                         *
 ***************************************************************************/

#define _IN_FPS

#include "externals.h"
#include "fps.h"
#include "gpu.h"

////////////////////////////////////////////////////////////////////////
// FPS stuff
////////////////////////////////////////////////////////////////////////

LARGE_INTEGER CPUFrequency, PerformanceCounter;

float          fFrameRateHz=0;
DWORD          dwFrameRateTicks=16;
float          fFrameRate;
int            iFrameLimit;
int            UseFrameLimit=0;
int            UseFrameSkip=0;

////////////////////////////////////////////////////////////////////////
// FPS skipping / limit
////////////////////////////////////////////////////////////////////////
       
BOOL   bInitCap = TRUE;
float  fps_skip = 0;
float  fps_cur  = 0;

////////////////////////////////////////////////////////////////////////

#define MAXLACE 16

void CheckFrameRate(void)
{                           
 if(UseFrameSkip)                                      // skipping mode?
  {
   if(!(dwActFixes&0x80))                              // not old skipping mode?
    {
     dwLaceCnt++;                                      // -> store cnt of vsync between frames
     if(dwLaceCnt>=MAXLACE && UseFrameLimit)           // -> if there are many laces without screen toggling,
      {                                                //    do std frame limitation
       if(dwLaceCnt==MAXLACE) bInitCap=TRUE;
       FrameCap();
      }
    }
   else if(UseFrameLimit) FrameCap();
   calcfps();                                          // -> calc fps display in skipping mode
  }                                                  
 else                                                  // non-skipping mode:
  {
   if(UseFrameLimit) FrameCap();                       // -> do it
   if(ulKeybits&KEY_SHOWFPS) calcfps();                // -> and calc fps display
  }
}                      

////////////////////////////////////////////////////////////////////////
// WIN VERSION
////////////////////////////////////////////////////////////////////////

BOOL           IsPerformanceCounter = FALSE;

void FrameCap (void)                                   // frame limit func
{
 static DWORD curticks, lastticks, _ticks_since_last_update;
 static DWORD TicksToWait = 0;
 static LARGE_INTEGER  CurrentTime;
 static LARGE_INTEGER  LastTime;
 static BOOL SkipNextWait = FALSE;
 BOOL Waiting = TRUE;

//---------------------------------------------------------
 if(bInitCap)
  {
   bInitCap=FALSE;
   if (IsPerformanceCounter)
    QueryPerformanceCounter(&LastTime);
   lastticks = timeGetTime();
   TicksToWait=0;
   return;
  }
//---------------------------------------------------------

 if (IsPerformanceCounter)
  {
   QueryPerformanceCounter(&CurrentTime);
   _ticks_since_last_update = CurrentTime.LowPart - LastTime.LowPart;

   //---------------------------------------------------------
   curticks = timeGetTime();
   if(_ticks_since_last_update>(CPUFrequency.LowPart>>1))
    {
     if(curticks < lastticks)
          _ticks_since_last_update = dwFrameRateTicks+TicksToWait+1;
     else _ticks_since_last_update = (CPUFrequency.LowPart * (curticks - lastticks))/1000;
    }
   //---------------------------------------------------------

   if ((_ticks_since_last_update > TicksToWait) || 
       (CurrentTime.LowPart < LastTime.LowPart))
    {
     LastTime.HighPart = CurrentTime.HighPart;
     LastTime.LowPart  = CurrentTime.LowPart;

     lastticks=curticks;

     if((_ticks_since_last_update-TicksToWait) > dwFrameRateTicks)
          TicksToWait=0;
     else TicksToWait=dwFrameRateTicks-(_ticks_since_last_update-TicksToWait);
    }
   else
    {
     while (Waiting)
      {
       QueryPerformanceCounter(&CurrentTime);
       _ticks_since_last_update = CurrentTime.LowPart - LastTime.LowPart;

       //---------------------------------------------------------
       curticks = timeGetTime();
       if(_ticks_since_last_update>(CPUFrequency.LowPart>>1))   
        {
         if(curticks < lastticks)
              _ticks_since_last_update = TicksToWait+1;
         else _ticks_since_last_update = (CPUFrequency.LowPart * (curticks - lastticks))/1000;
        }
       //---------------------------------------------------------

       if ((_ticks_since_last_update > TicksToWait) || 
           (CurrentTime.LowPart < LastTime.LowPart))
        {
         Waiting = FALSE;

         lastticks=curticks;

         LastTime.HighPart = CurrentTime.HighPart;
         LastTime.LowPart = CurrentTime.LowPart;
         TicksToWait = dwFrameRateTicks;
        }
      }
    }
  }
 else
  {
   curticks = timeGetTime();
   _ticks_since_last_update = curticks - lastticks;

   if ((_ticks_since_last_update > TicksToWait) || 
       (curticks < lastticks))
    {
     lastticks = curticks;

     if((_ticks_since_last_update-TicksToWait) > dwFrameRateTicks)
          TicksToWait=0;
     else TicksToWait=dwFrameRateTicks-(_ticks_since_last_update-TicksToWait);
    }
   else
    {
     while (Waiting)
      {
       curticks = timeGetTime();
       _ticks_since_last_update = curticks - lastticks;
       if ((_ticks_since_last_update > TicksToWait) || 
           (curticks < lastticks))
        {
         Waiting = FALSE;
         lastticks = curticks;
         TicksToWait = dwFrameRateTicks;
        }
      }
    }
  }
}

////////////////////////////////////////////////////////////////////////

#define MAXSKIP 120

void FrameSkip(void)
{
 static int   iNumSkips=0,iAdditionalSkip=0;           // number of additional frames to skip
 static DWORD dwLastLace=0;                            // helper var for frame limitation
 static DWORD curticks, lastticks, _ticks_since_last_update;
 static LARGE_INTEGER  CurrentTime;
 static LARGE_INTEGER  LastTime;

 if(!dwLaceCnt) return;                                // important: if no updatelace happened, we ignore it completely

 if(iNumSkips)                                         // we are in pure skipping mode?
  {
   dwLastLace+=dwLaceCnt;                              // -> calc frame limit helper (number of laces)
   bSkipNextFrame = TRUE;                              // -> we skip next frame as well
   iNumSkips--;                                        // -> ok, one done
  }
 else                                                  // ok, no additional skipping has to be done... 
  {                                                    // we check now, if some limitation is needed, or a new skipping has to get started
   DWORD dwWaitTime;

   if(bInitCap || bSkipNextFrame)                      // first time or we skipped before?
    {
     if(UseFrameLimit && !bInitCap)                    // frame limit wanted and not first time called?
      {
       DWORD dwT=_ticks_since_last_update;             // -> that's the time of the last drawn frame
       dwLastLace+=dwLaceCnt;                          // -> and that's the number of updatelace since the start of the last drawn frame

       if (IsPerformanceCounter)                       // -> now we calc the time of the last drawn frame + the time we spent skipping
        {
         QueryPerformanceCounter(&CurrentTime);
         _ticks_since_last_update= dwT+CurrentTime.LowPart - LastTime.LowPart;
        }
       else
        {
         curticks = timeGetTime();
         _ticks_since_last_update= dwT+curticks - lastticks;
        }

       dwWaitTime=dwLastLace*dwFrameRateTicks;         // -> and now we calc the time the real psx would have needed

       if(_ticks_since_last_update<dwWaitTime)         // -> we were too fast?
        {                      
         if((dwWaitTime-_ticks_since_last_update)>     // -> some more security, to prevent
            (60*dwFrameRateTicks))                     //    wrong waiting times
          _ticks_since_last_update=dwWaitTime;

         while(_ticks_since_last_update<dwWaitTime)    // -> loop until we have reached the real psx time
          {                                            //    (that's the additional limitation, yup)
           if (IsPerformanceCounter)
            {
             QueryPerformanceCounter(&CurrentTime);
             _ticks_since_last_update = dwT+CurrentTime.LowPart - LastTime.LowPart;
            }
           else
            {
             curticks = timeGetTime();
             _ticks_since_last_update = dwT+curticks - lastticks;
            }
          }
        }
       else                                            // we were still too slow ?!!?
        {
         if(iAdditionalSkip<MAXSKIP)                   // -> well, somewhen we really have to stop skipping on very slow systems
          {
           iAdditionalSkip++;                          // -> inc our watchdog var
           dwLaceCnt=0;                                // -> reset lace count
           if (IsPerformanceCounter)                   // -> ok, start time of the next frame
            QueryPerformanceCounter(&LastTime);
           lastticks = timeGetTime();
           return;                                     // -> done, we will skip next frame to get more speed (SkipNextFrame still TRUE)
          } 
        }
      }

     bInitCap=FALSE;                                   // -> ok, we have inited the frameskip func
     iAdditionalSkip=0;                                // -> init additional skip
     bSkipNextFrame=FALSE;                             // -> we don't skip the next frame
     if (IsPerformanceCounter)                         // -> we store the start time of the next frame
      QueryPerformanceCounter(&LastTime);
     lastticks = timeGetTime();
     dwLaceCnt=0;                                      // -> and we start to count the laces 
     dwLastLace=0;      
     _ticks_since_last_update=0;
     return;                                           // -> done, the next frame will get drawn
    }

   bSkipNextFrame=FALSE;                               // init the frame skip signal to 'no skipping' first

   if (IsPerformanceCounter)                           // get the current time (we are now at the end of one drawn frame)
    {
     QueryPerformanceCounter(&CurrentTime);
     _ticks_since_last_update = CurrentTime.LowPart - LastTime.LowPart;
    }
   else
    {
     curticks = timeGetTime();
     _ticks_since_last_update = curticks - lastticks;
    }

   dwLastLace=dwLaceCnt;                               // store curr count (frame limitation helper)
   dwWaitTime=dwLaceCnt*dwFrameRateTicks;              // calc the 'real psx lace time'

   if(_ticks_since_last_update>dwWaitTime)             // hey, we needed way too long for that frame...
    {
     if(UseFrameLimit)                                 // if limitation, we skip just next frame,
      {                                                // and decide after, if we need to do more
       iNumSkips=0;
      }
     else
      {
       iNumSkips=_ticks_since_last_update/dwWaitTime;  // -> calc number of frames to skip to catch up
       iNumSkips--;                                    // -> since we already skip next frame, one down
       if(iNumSkips>MAXSKIP) iNumSkips=MAXSKIP;        // -> well, somewhere we have to draw a line
      }
     bSkipNextFrame = TRUE;                            // -> signal for skipping the next frame
    }
   else                                                // we were faster than real psx? fine :)
   if(UseFrameLimit)                                   // frame limit used? so we wait til the 'real psx time' has been reached
    {
     if(dwLaceCnt>MAXLACE)                             // -> security check
      _ticks_since_last_update=dwWaitTime;

     while(_ticks_since_last_update<dwWaitTime)        // just do a waiting loop...
      {
       if (IsPerformanceCounter)
        {
         QueryPerformanceCounter(&CurrentTime);
         _ticks_since_last_update = CurrentTime.LowPart - LastTime.LowPart;
        }
       else
        {
         curticks = timeGetTime();
         _ticks_since_last_update = curticks - lastticks;
        }
      }
    }

   if (IsPerformanceCounter)                           // ok, start time of the next frame
    QueryPerformanceCounter(&LastTime);
   lastticks = timeGetTime();
  }

 dwLaceCnt=0;                                          // init lace counter
}

////////////////////////////////////////////////////////////////////////

void calcfps(void)                                     // fps calculations
{
 static DWORD curticks,_ticks_since_last_update,lastticks;
 static long   fps_cnt = 0;
 static DWORD  fps_tck = 1;
 static LARGE_INTEGER  CurrentTime;
 static LARGE_INTEGER  LastTime;
 static long   fpsskip_cnt = 0;
 static DWORD  fpsskip_tck = 1;

 if(IsPerformanceCounter)
  {
   QueryPerformanceCounter(&CurrentTime);
   _ticks_since_last_update=CurrentTime.LowPart-LastTime.LowPart;

   //--------------------------------------------------//
   curticks = timeGetTime();
   if(_ticks_since_last_update>(CPUFrequency.LowPart>>1))   
    _ticks_since_last_update = (CPUFrequency.LowPart * (curticks - lastticks))/1000;
   lastticks=curticks;
   //--------------------------------------------------//

   if(UseFrameSkip && !UseFrameLimit && _ticks_since_last_update)                                    
    fps_skip=min(fps_skip,(((float)CPUFrequency.LowPart) / ((float)_ticks_since_last_update) +1.0f));

   LastTime.HighPart = CurrentTime.HighPart;
   LastTime.LowPart = CurrentTime.LowPart;
  }
 else
  {
   curticks = timeGetTime();
   _ticks_since_last_update=curticks-lastticks;

   if(UseFrameSkip && !UseFrameLimit && _ticks_since_last_update)
    fps_skip=min(fps_skip,((float)1000/(float)_ticks_since_last_update+1.0f));

   lastticks = curticks;
  }

 if(UseFrameSkip && UseFrameLimit)
  {
   fpsskip_tck += _ticks_since_last_update;

   if(++fpsskip_cnt==2)
    {
     if(IsPerformanceCounter)
      fps_skip = ((float)CPUFrequency.LowPart) / ((float)fpsskip_tck) *2.0f;
     else
      fps_skip = (float)2000/(float)fpsskip_tck;

     fps_skip +=6.0f;

     fpsskip_cnt = 0;
     fpsskip_tck = 1;
    }
  }

 fps_tck += _ticks_since_last_update;

 if(++fps_cnt==10)
  {
   if(IsPerformanceCounter)
    fps_cur = ((float)CPUFrequency.LowPart) / ((float)fps_tck) *10.0f;
   else
    fps_cur = (float)10000/(float)fps_tck;

   fps_cnt = 0;
   fps_tck = 1;

   if(UseFrameLimit && fps_cur>fFrameRateHz)           // optical adjust ;) avoids flickering fps display
    fps_cur=fFrameRateHz;
  }
}

////////////////////////////////////////////////////////////////////////
// PC FPS skipping / limit
////////////////////////////////////////////////////////////////////////

void PCFrameCap (void)
{
 static DWORD curticks, lastticks, _ticks_since_last_update;
 static DWORD TicksToWait = 0;
 static LARGE_INTEGER  CurrentTime;
 static LARGE_INTEGER  LastTime;
 BOOL Waiting = TRUE;

 while (Waiting)
  {
   if (IsPerformanceCounter)
    {
     QueryPerformanceCounter(&CurrentTime);
     _ticks_since_last_update = CurrentTime.LowPart - LastTime.LowPart;

     //------------------------------------------------//
     curticks = timeGetTime();
     if(_ticks_since_last_update>(CPUFrequency.LowPart>>1))   
      {
       if(curticks < lastticks)
            _ticks_since_last_update = TicksToWait+1;
       else _ticks_since_last_update = (CPUFrequency.LowPart * (curticks - lastticks))/1000;
      }
     //------------------------------------------------//

     if ((_ticks_since_last_update > TicksToWait) ||
         (CurrentTime.LowPart < LastTime.LowPart))
      {
       Waiting = FALSE;
       lastticks=curticks;
       LastTime.HighPart = CurrentTime.HighPart;
       LastTime.LowPart = CurrentTime.LowPart;
       TicksToWait = (unsigned long)(CPUFrequency.LowPart / fFrameRateHz);
      }
    }
   else
    {
     curticks = timeGetTime();
     _ticks_since_last_update = curticks - lastticks;
     if ((_ticks_since_last_update > TicksToWait) || 
         (curticks < lastticks))
      {
       Waiting = FALSE;
       lastticks = curticks;
       TicksToWait = (1000 / (DWORD)fFrameRateHz);
      }
    }
  }
}

////////////////////////////////////////////////////////////////////////

void PCcalcfps(void)
{
 static DWORD curticks,_ticks_since_last_update,lastticks;
 static long  fps_cnt = 0;
 static float fps_acc = 0;
 static LARGE_INTEGER  CurrentTime;
 static LARGE_INTEGER  LastTime;
 float CurrentFPS=0;    
 
 if(IsPerformanceCounter)
  {
   QueryPerformanceCounter(&CurrentTime);
   _ticks_since_last_update=CurrentTime.LowPart-LastTime.LowPart;

   //--------------------------------------------------//
   curticks = timeGetTime();
   if(_ticks_since_last_update>(CPUFrequency.LowPart>>1))   
    _ticks_since_last_update = (CPUFrequency.LowPart * (curticks - lastticks))/1000;
   lastticks=curticks;
   //--------------------------------------------------//

   if(_ticks_since_last_update)
    {
     CurrentFPS = ((float)CPUFrequency.LowPart) / ((float)_ticks_since_last_update);
    }
   else CurrentFPS = 0;
   LastTime.HighPart = CurrentTime.HighPart;
   LastTime.LowPart = CurrentTime.LowPart;
  }
 else
  {
   curticks = timeGetTime();
   if(_ticks_since_last_update=curticks-lastticks)
        CurrentFPS=(float)1000/(float)_ticks_since_last_update;
   else CurrentFPS = 0;
   lastticks = curticks;
  }

 fps_acc += CurrentFPS;

 if(++fps_cnt==10)
  {
   fps_cur = fps_acc / 10;
   fps_acc = 0;
   fps_cnt = 0;
  }
 
 fps_skip=CurrentFPS+1.0f;
}

////////////////////////////////////////////////////////////////////////

void SetAutoFrameCap(void)
{
 if(iFrameLimit==1)
  {
   fFrameRateHz = fFrameRate;
   if(IsPerformanceCounter)
        dwFrameRateTicks=(DWORD)(CPUFrequency.LowPart / fFrameRateHz);
   else dwFrameRateTicks=(1000 / (DWORD)fFrameRateHz);
   return;
  }

 if(dwActFixes&32)
  {
   if (PSXDisplay.Interlaced)
        fFrameRateHz = PSXDisplay.PAL?50.0f:60.0f;
   else fFrameRateHz = PSXDisplay.PAL?25.0f:30.0f;
  }
 else
  {
   fFrameRateHz = PSXDisplay.PAL?50.0f:59.94f;
   if(IsPerformanceCounter)
        dwFrameRateTicks=(DWORD)(CPUFrequency.LowPart / fFrameRateHz);
   else dwFrameRateTicks=(1000 / (DWORD)fFrameRateHz);
  }
}

////////////////////////////////////////////////////////////////////////

void SetFPSHandler(void)
{
 if (QueryPerformanceFrequency (&CPUFrequency))        // timer mode
      IsPerformanceCounter = TRUE;
 else IsPerformanceCounter = FALSE;
}

////////////////////////////////////////////////////////////////////////

void InitFPS(void)
{
 bInitCap = TRUE;

 if(fFrameRateHz==0) fFrameRateHz=fFrameRate;          // set user framerate

 if(IsPerformanceCounter)
      dwFrameRateTicks=(DWORD)(CPUFrequency.LowPart / fFrameRateHz);
 else dwFrameRateTicks=(1000 / (DWORD)fFrameRateHz);
}

////////////////////////////////////////////////////////////////////////