osdep/timer-darwin.c

   1 /*
   2  * Precise timer routines using Mach timing
   3  *
   4  * Copyright (c) 2003-2004, Dan Villiom Podlaski Christiansen
   5  *
   6  * Permission is hereby granted, free of charge, to any person
   7  * obtaining a copy of this software and associated documentation
   8  * files (the "Software"), to deal in the Software without
   9  * restriction, including without limitation the rights to use, copy,
  10  * modify, merge, publish, distribute, sublicense, and/or sell copies
  11  * of the Software, and to permit persons to whom the Software is
  12  * furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be
  15  * included in all copies or substantial portions of the Software.
  16  */
  17
  18 #include <unistd.h>
  19 #include <stdlib.h>
  20 #include <time.h>
  21 #include <math.h>
  22 #include <sys/time.h>
  23 #include <mach/mach_time.h>
  24
  25 #include "config.h"
  26 #include "mp_msg.h"
  27 #include "timer.h"
  28
  29 /* global variables */
  30 static double relative_time, startup_time;
  31 static double timebase_ratio;
  32
  33 const char *timer_name = "Darwin accurate";
  34
  35
  36
  37 /* the core sleep function, uses floats and is used in MPlayer G2 */
  38 float sleep_accurate(float time_frame)
  39 {
  40         uint64_t deadline = time_frame / timebase_ratio + mach_absolute_time();
  41
  42         mach_wait_until(deadline);
  43
  44         return (mach_absolute_time() - deadline) * timebase_ratio;
  45 }
  46
  47 /* wrapper for MPlayer G1 */
  48 int usec_sleep(int usec_delay)
  49 {
  50   return sleep_accurate(usec_delay / 1e6) * 1e6;
  51 }
  52
  53
  54 /* current time in microseconds */
  55 unsigned int GetTimer()
  56 {
  57   return (unsigned int)((mach_absolute_time() * timebase_ratio - startup_time)
  58                         * 1e6);
  59 }
  60
  61 /* current time in milliseconds */
  62 unsigned int GetTimerMS()
  63 {
  64   return (unsigned int)((mach_absolute_time() * timebase_ratio - startup_time)
  65                         * 1e3);
  66 }
  67
  68 /* time spent between now and last call in seconds */
  69 float GetRelativeTime()
  70 {
  71   double last_time = relative_time;
  72
  73   if (!relative_time)
  74     InitTimer();
  75
  76   relative_time = mach_absolute_time() * timebase_ratio;
  77
  78   return (float)(relative_time-last_time);
  79 }
  80
  81 /* initialize timer, must be called at least once at start */
  82 void InitTimer()
  83 {
  84   struct mach_timebase_info timebase;
  85
  86   mach_timebase_info(&timebase);
  87   timebase_ratio = (double)timebase.numer / (double)timebase.denom
  88     * (double)1e-9;
  89
  90   relative_time = startup_time =
  91     (double)(mach_absolute_time() * timebase_ratio);
  92 }
  93
  94 #if 0
  95 #include <stdio.h>
  96
  97 int main(void) {
  98   int i,j, r, c = 200;
  99   long long t = 0;
 100
 101   InitTimer();
 102
 103   for (i = 0; i < c; i++) {
 104     const int delay = rand() / (RAND_MAX / 1e5);
 105     j = GetTimer();
 106 #if 1
 107     r = usec_sleep(delay);
 108 #else
 109     r = sleep_accurate(delay / 1e6) * 1e6;
 110 #endif
 111     j = (GetTimer() - j) - delay;
 112     printf("sleep time:%8i %5i (%i)\n", delay, j, j - r);
 113     t += j - r;
 114   }
 115   fprintf(stderr, "average error:\t%lli\n", t / c);
 116
 117   return 0;
 118 }
 119 #endif