drivers/sdl/throttle.c

   1 #include <sys/time.h>
   2 #include <unistd.h>
   3
   4 #include "../common/main.h"
   5 #include "../common/throttle.h"
   6 #include "../common/settings.h"
   7
   8
   9 extern uint8 PAL;
  10 extern int FSkip;
  11 static int usec_aim = 0, usec_done = 0;
  12 static int skip_count = 0;
  13
  14 void RefreshThrottleFPS(void)
  15 {
  16         usec_aim = usec_done = skip_count = 0;
  17 }
  18
  19 void SpeedThrottle(void)
  20 {
  21         static struct timeval tv_prev;
  22         struct timeval tv_now;
  23         int delta_nom = PAL ? 19997 : 16639; // ~50.007, 19.997 ms/frame : ~60.1, 16.639 ms/frame
  24
  25
  26         if (usec_done == 0) { // first time
  27                 usec_done = 1;
  28                 gettimeofday(&tv_prev, 0);
  29                 return;
  30         }
  31
  32         gettimeofday(&tv_now, 0);
  33
  34         usec_aim += delta_nom;
  35         if (tv_now.tv_sec != tv_prev.tv_sec)
  36                 usec_done += 1000000;
  37         usec_done += tv_now.tv_usec - tv_prev.tv_usec;
  38
  39 #ifdef FRAMESKIP
  40         if (Settings.frameskip >= 0)
  41         {
  42                 if (skip_count >= Settings.frameskip)
  43                         skip_count = 0;
  44                 else {
  45                         skip_count++;
  46                         FSkip = 1;
  47                 }
  48         }
  49         else if (usec_done > usec_aim + 1024*4)
  50         {
  51                 /* auto frameskip */
  52                 if (usec_done - usec_aim > 1024*32)
  53                         usec_done = usec_aim = 1; // too much behind, try to recover..
  54                 else
  55                         FSkip = 1;
  56                 tv_prev = tv_now;
  57                 return;
  58         }
  59 #endif
  60
  61         tv_prev = tv_now;
  62         while (usec_done < usec_aim)
  63         {
  64                 usleep(300);
  65                 gettimeofday(&tv_now, 0);
  66
  67                 if (tv_now.tv_sec != tv_prev.tv_sec)
  68                         usec_done += 1000000;
  69                 usec_done += tv_now.tv_usec - tv_prev.tv_usec;
  70                 tv_prev = tv_now;
  71         }
  72         usec_done = usec_done - usec_aim + 1; // reset to prevent overflows
  73         usec_aim = 0;
  74 }
  75