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 timebase_ratio;
  31
  32 const char timer_name[] = "Darwin accurate";
  33
  34
  35
  36 /* the core sleep function, uses floats and is used in MPlayer G2 */
  37 static float sleep_accurate(float time_frame)
  38 {
  39         uint64_t deadline = time_frame / timebase_ratio + mach_absolute_time();
  40
  41         mach_wait_until(deadline);
  42
  43         return (mach_absolute_time() - deadline) * timebase_ratio;
  44 }
  45
  46 /* wrapper for MPlayer G1 */
  47 int usec_sleep(int usec_delay)
  48 {
  49   return sleep_accurate(usec_delay / 1e6) * 1e6;
  50 }
  51
  52
  53 /* current time in microseconds */
  54 unsigned int GetTimer(void)
  55 {
  56   return (unsigned int)(uint64_t)(mach_absolute_time() * timebase_ratio * 1e6);
  57 }
  58
  59 /* current time in milliseconds */
  60 unsigned int GetTimerMS(void)
  61 {
  62   return (unsigned int)(uint64_t)(mach_absolute_time() * timebase_ratio * 1e3);
  63 }
  64
  65 /* initialize timer, must be called at least once at start */
  66 void InitTimer(void)
  67 {
  68   struct mach_timebase_info timebase;
  69
  70   mach_timebase_info(&timebase);
  71   timebase_ratio = (double)timebase.numer / (double)timebase.denom
  72     * (double)1e-9;
  73 }
  74
  75 #if 0
  76 #include <stdio.h>
  77
  78 int main(void) {
  79   int i,j, r, c = 200;
  80   long long t = 0;
  81
  82   InitTimer();
  83
  84   for (i = 0; i < c; i++) {
  85     const int delay = rand() / (RAND_MAX / 1e5);
  86     j = GetTimer();
  87 #if 1
  88     r = usec_sleep(delay);
  89 #else
  90     r = sleep_accurate(delay / 1e6) * 1e6;
  91 #endif
  92     j = (GetTimer() - j) - delay;
  93     printf("sleep time:%8i %5i (%i)\n", delay, j, j - r);
  94     t += j - r;
  95   }
  96   fprintf(stderr, "average error:\t%lli\n", t / c);
  97
  98   return 0;
  99 }
 100 #endif