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 <stdint.h>
  20 #include <stdlib.h>
  21 #include <time.h>
  22 #include <math.h>
  23 #include <sys/time.h>
  24 #include <mach/mach_time.h>
  25
  26 #include "config.h"
  27 #include "mp_msg.h"
  28 #include "timer.h"
  29
  30 /* global variables */
  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 static 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(void)
  56 {
  57   return (unsigned int)(uint64_t)(mach_absolute_time() * timebase_ratio * 1e6);
  58 }
  59
  60 /* current time in milliseconds */
  61 unsigned int GetTimerMS(void)
  62 {
  63   return (unsigned int)(uint64_t)(mach_absolute_time() * timebase_ratio * 1e3);
  64 }
  65
  66 /* initialize timer, must be called at least once at start */
  67 void InitTimer(void)
  68 {
  69   struct mach_timebase_info timebase;
  70
  71   mach_timebase_info(&timebase);
  72   timebase_ratio = (double)timebase.numer / (double)timebase.denom
  73     * (double)1e-9;
  74 }
  75
  76 #if 0
  77 #include <stdio.h>
  78
  79 int main(void) {
  80   int i,j, r, c = 200;
  81   long long t = 0;
  82
  83   InitTimer();
  84
  85   for (i = 0; i < c; i++) {
  86     const int delay = rand() / (RAND_MAX / 1e5);
  87     j = GetTimer();
  88 #if 1
  89     r = usec_sleep(delay);
  90 #else
  91     r = sleep_accurate(delay / 1e6) * 1e6;
  92 #endif
  93     j = (GetTimer() - j) - delay;
  94     printf("sleep time:%8i %5i (%i)\n", delay, j, j - r);
  95     t += j - r;
  96   }
  97   fprintf(stderr, "average error:\t%lli\n", t / c);
  98
  99   return 0;
 100 }
 101 #endif