/*
 * Precise timer routines using CoreFoundation
 *
 * (C) 2003 Dan Christiansen
 *
 * Released into the public domain.
 *
 * Changelog:
 *  07/05/2003  sleep_accurate() merged from timer-lx.c
 *              updated to mplayer-g2
 *  11/05/2003  rewritten using mach timing
 *
 *
 * TODO:
 *  - figure out how to get a mach port w/o CoreFoundation
 *  - use the run loop for long intervals
 */

/* About CFRunLoop:
 *
 * Being a run loop, it can be up to several seconds (or more) late if
 * another task runs. CFRunLoop offers interruptable sleep, but does not
 * deploy busy waiting; it uses the system even manager. It does seem to 
 * use more CPU than blocking sleep, and is less accurate.
 *
 * About mach timing:
 *
 * These are kernel space timers, and appear to be the most accurate timers
 * available on Darwin. clock_sleep() is always a bit late, but never early.
 */

#include <CoreFoundation/CFMachPort.h>
#include <mach/mach_time.h>

#include "../config.h"
#include "timer.h"

/* global variables */
static uint64_t relative_time, startup_time;
static struct mach_timebase_info timebase;
static mach_port_t mach_port;


/* inaccurate timing with CFRunLoop */
int usec_sleep(int usec_delay)
{
  float start, end;

  start = CFAbsoluteTimeGetCurrent();
  CFRunLoopRunInMode(kCFRunLoopDefaultMode, usec_delay/1000000.0, false);
  end = CFAbsoluteTimeGetCurrent();

  return (usec_delay-(end-start))*1000000;
}


/* accurate kernel-based timing */
float sleep_accurate(float time_frame)
{
  mach_timespec_t ts;

  /* clock_sleep is always a little late */
  ts.tv_sec  = (long)time_frame;
  ts.tv_nsec = (long)((time_frame - 0.010) * 1000000000.0);

  GetRelativeTime();
  clock_sleep(NULL, TIME_RELATIVE, ts, NULL);
  time_frame -= GetRelativeTime();

  if (time_frame < -0.005 || time_frame > 0.010)
    mp_msg(MSGT_AVSYNC,MSGL_V, "time_frame=%f out of bounds! \n",
	   time_frame);
  }

  return time_frame;
}


/* Returns current time in microseconds */
unsigned int GetTimer()
{
  return (unsigned int)((double)(mach_absolute_time() - startup_time) / 
			timebase.denom * timebase.numer / 1000);
}  


/* Returns current time in milliseconds */
unsigned int GetTimerMS()
{
  return (unsigned int)(GetTimer() / 1000);
}


/* Returns time spent between now and last call in seconds */
float GetRelativeTime()
{
  uint64_t last_time = relative_time;
  
  if (!relative_time)
    InitTimer();
  
  relative_time = mach_absolute_time();

  return (float)(relative_time-last_time) / timebase.denom * 
    timebase.numer / 1000000000;
}


/* dummy callback function */
static void mach_callback(CFMachPortRef port,  
			  void *msg, CFIndex size,  
			  void *info)
{

}


/* Initialize timer, must be called at least once at start */
void InitTimer()
{
  mach_port =
    CFMachPortGetPort(CFMachPortCreate(NULL, mach_callback, NULL, NULL));
    mach_timebase_info(&timebase);
  
  relative_time = startup_time = mach_absolute_time();
}


#if 0
int main()
{
  int i;
  
  InitTimer();
  
  for (i = 1; i < 20; i++) {
    printf("Time: %u  sleep_accurate(): %lf\n", GetTimerMS(), sleep_accurate(0.1));
  }
}
#endif