drivers/gp2x/throttle.c

   1 #include <sys/time.h>
   2 #include "main.h"
   3 #include "gp2x.h"
   4 #include "throttle.h"
   5
   6
   7 extern uint8 PAL;
   8 extern int FSkip;
   9 static int usec_aim = 0, usec_done = 0;
  10 static int skip_count = 0;
  11
  12 void RefreshThrottleFPS(void)
  13 {
  14         usec_aim = usec_done = skip_count = 0;
  15 }
  16
  17 void SpeedThrottle(void)
  18 {
  19         static struct timeval tv_prev;
  20         struct timeval tv_now;
  21         int delta_nom = PAL ? 19997 : 16639; // ~50.007, 19.997 ms/frame : ~60.1, 16.639 ms/frame
  22
  23
  24         if (usec_done == 0) { // first time
  25                 usec_done = 1;
  26                 gettimeofday(&tv_prev, 0);
  27                 return;
  28         }
  29
  30         gettimeofday(&tv_now, 0);
  31
  32         usec_aim += delta_nom;
  33         if (tv_now.tv_sec != tv_prev.tv_sec)
  34                 usec_done += 1000000;
  35         usec_done += tv_now.tv_usec - tv_prev.tv_usec;
  36
  37 #ifdef FRAMESKIP
  38         if (Settings.frameskip >= 0)
  39         {
  40                 if (skip_count >= Settings.frameskip)
  41                         skip_count = 0;
  42                 else {
  43                         skip_count++;
  44                         FSkip = 1;
  45                 }
  46         }
  47         else if (usec_done > usec_aim + 1024*4)
  48         {
  49                 /* auto frameskip */
  50                 if (usec_done - usec_aim > 1024*32)
  51                         usec_done = usec_aim = 1; // too much behind, try to recover..
  52                 else
  53                         FSkip = 1;
  54                 tv_prev = tv_now;
  55                 return;
  56         }
  57 #endif
  58
  59         tv_prev = tv_now;
  60         while (usec_done < usec_aim)
  61         {
  62                 gettimeofday(&tv_now, 0);
  63
  64                 if (tv_now.tv_sec != tv_prev.tv_sec)
  65                         usec_done += 1000000;
  66                 usec_done += tv_now.tv_usec - tv_prev.tv_usec;
  67                 tv_prev = tv_now;
  68         }
  69         usec_done = usec_done - usec_aim + 1; // reset to prevent overflows
  70         usec_aim = 0;
  71 }
  72