/***************************************************************************
                          fps.c  -  description
                             -------------------
    begin                : Sun Mar 08 2009
    copyright            : (C) 1999-2009 by Pete Bernert
    web                  : www.pbernert.com   
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   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.                                              *
 *                                                                         *
 ***************************************************************************/

//*************************************************************************// 
// History of changes:
//
// 2009/03/08 - Pete  
// - generic cleanup for the Peops release
//
//*************************************************************************// 

#include "stdafx.h"

#define _IN_FPS

#include "externals.h"

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

BOOL           bIsPerformanceCounter=FALSE;
float          fFrameRateHz=0;
DWORD          dwFrameRateTicks=16;
float          fFrameRate;
int            iFrameLimit;
BOOL           bUseFrameLimit=FALSE;
BOOL           bUseFrameSkip=0;
DWORD          dwLaceCnt=0;

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

BOOL         bInitCap = TRUE; 
float        fps_skip = 0;
float        fps_cur  = 0;

#define TIMEBASE 100000

unsigned long timeGetTime()
{
 struct timeval tv;
 gettimeofday(&tv, 0);                                // well, maybe there are better ways
 return tv.tv_sec * 100000 + tv.tv_usec/10;           // to do that in linux, but at least it works
}

void FrameCap(void)
{
 static unsigned long curticks, lastticks, _ticks_since_last_update;
 static unsigned long TicksToWait = 0;
 bool Waiting = TRUE;

  {
   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
#define MAXLACE 16

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;

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

 if(iNumSkips)                                         // we are in skipping mode?
  {
   dwLastLace+=dwLaceCnt;                              // -> calc frame limit helper (number of laces)
   bSkipNextFrame = TRUE;                              // -> we skip next frame
   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(bUseFrameLimit && !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

       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)
           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
           lastticks = timeGetTime();
           return;                                     // -> done, we will skip next frame to get more speed
          }
        }
      }

     bInitCap=FALSE;                                   // -> ok, we have inited the frameskip func
     iAdditionalSkip=0;                                // -> init additional skip
     bSkipNextFrame=FALSE;                             // -> we don't skip the next frame
     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

   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(bUseFrameLimit)                                // 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(bUseFrameLimit)                                  // 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...
      {
       curticks = timeGetTime();
       _ticks_since_last_update = curticks - lastticks;
      }
    }

   lastticks = timeGetTime();
  }

 dwLaceCnt=0;                                          // init lace counter
}

void calcfps(void) 
{ 
 static unsigned long curticks,_ticks_since_last_update,lastticks; 
 static long   fps_cnt = 0;
 static unsigned long  fps_tck = 1; 
 static long           fpsskip_cnt = 0;
 static unsigned long  fpsskip_tck = 1;
 
  { 
   curticks = timeGetTime(); 
   _ticks_since_last_update=curticks-lastticks; 
 
   if(bUseFrameSkip && !bUseFrameLimit && _ticks_since_last_update) 
    fps_skip=min(fps_skip,((float)TIMEBASE/(float)_ticks_since_last_update+1.0f));
 
   lastticks = curticks; 
  } 
 
 if(bUseFrameSkip && bUseFrameLimit)
  {
   fpsskip_tck += _ticks_since_last_update;

   if(++fpsskip_cnt==2)
    {
     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) 
  { 
   fps_cur = (float)(TIMEBASE*10)/(float)fps_tck; 

   fps_cnt = 0; 
   fps_tck = 1; 
 
   if(bUseFrameLimit && fps_cur>fFrameRateHz)            // optical adjust ;) avoids flickering fps display 
    fps_cur=fFrameRateHz; 
  } 
} 

void PCFrameCap (void) 
{
 static unsigned long curticks, lastticks, _ticks_since_last_update;
 static unsigned long TicksToWait = 0;
 bool Waiting = TRUE; 
 
 while (Waiting) 
  {
   curticks = timeGetTime(); 
   _ticks_since_last_update = curticks - lastticks; 
   if ((_ticks_since_last_update > TicksToWait) ||  
       (curticks < lastticks)) 
    { 
     Waiting = FALSE; 
     lastticks = curticks; 
     TicksToWait = (TIMEBASE / (unsigned long)fFrameRateHz); 
    } 
  } 
} 

void PCcalcfps(void) 
{ 
 static unsigned long curticks,_ticks_since_last_update,lastticks; 
 static long  fps_cnt = 0; 
 static float fps_acc = 0;
 float CurrentFPS=0;     
  
 curticks = timeGetTime(); 
 _ticks_since_last_update=curticks-lastticks;
 if(_ticks_since_last_update) 
      CurrentFPS=(float)TIMEBASE/(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;
   dwFrameRateTicks=(TIMEBASE / (unsigned long)fFrameRateHz);
   return;
  }

 if(dwActFixes&128)
  {
   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(PSXDisplay.PAL)
    {
     if (STATUSREG&GPUSTATUS_INTERLACED)
           fFrameRateHz=33868800.0f/677343.75f;        // 50.00238
      else fFrameRateHz=33868800.0f/680595.00f;        // 49.76351
    }                                                     
   else
    {
     if (STATUSREG&GPUSTATUS_INTERLACED)
           fFrameRateHz=33868800.0f/565031.25f;        // 59.94146
      else fFrameRateHz=33868800.0f/566107.50f;        // 59.82750
    }

   dwFrameRateTicks=(TIMEBASE / (unsigned long)fFrameRateHz);
  }
}

void SetFrameRateConfig(void)
{
 if(!fFrameRate) fFrameRate=200.0f;

 if(fFrameRateHz==0) 
  {                                                    
   if(iFrameLimit==2) fFrameRateHz=59.94f;             // auto framerate? set some init val (no pal/ntsc known yet)
   else               fFrameRateHz=fFrameRate;         // else set user framerate
  }

 dwFrameRateTicks=(TIMEBASE / (unsigned long)fFrameRateHz);

 if(iFrameLimit==2) SetAutoFrameCap();
}

void InitFrameCap(void)
{
}

void ReInitFrameCap(void)
{
}

void CheckFrameRate(void)                              // called in updatelace (on every emulated psx vsync)
{
 if(bUseFrameSkip) 
  {
   if(!(dwActFixes&0x100))
    {
     dwLaceCnt++;                                      // -> and store cnt of vsync between frames
     if(dwLaceCnt>=MAXLACE && bUseFrameLimit) 
      {
       if(dwLaceCnt==MAXLACE) bInitCap=TRUE;
       FrameCap();
      }
    }
   else if(bUseFrameLimit) FrameCap();
   calcfps();                                          // -> calc fps display in skipping mode
  }                                                  
 else                                                  // -> non-skipping mode:
  {
   if(bUseFrameLimit) FrameCap();
   if(ulKeybits&KEY_SHOWFPS) calcfps();  
  }
}

void CALLBACK GPUsetframelimit(unsigned long option)   // new EPSXE interface func: main emu can enable/disable fps limitation this way
{
 bInitCap = TRUE;

 if(option==1)                                         // emu says: limit
  {
   bUseFrameLimit=TRUE;bUseFrameSkip=FALSE;iFrameLimit=2;
   SetAutoFrameCap();
  }
 else                                                  // emu says: no limit
  {
   bUseFrameLimit=FALSE;
  }
}