/*
 * Semi-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  simplification, description & cleanup
 *
 */

/* About CFRunLoop:
 *
 * - Minimum sleep interval seems to be 0.000025s
 * - The common accuracy is in the order 0.0003s
 * - Sometimes, maybe 1 in 10 runs, it is 0.001s-0.015s late.
 *
 * Being a run loop, it can be up to several seconds (or more) late if
 * another task runs. It appears to never be too early.
 *
 * CFRunLoop offers interruptable sleep, but does not deploy busy waiting;
 * it uses the system even manager.
 */

#include <CoreFoundation/CFRunLoop.h>
#include <time.h>

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


static CFAbsoluteTime relative_time;


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;
}

/* timing without rounding errors */
float sleep_accurate(float time_frame)
{
  const float min=0.01;
  float start, end;

  if (time_frame > min) {
    start = CFAbsoluteTimeGetCurrent();
    CFRunLoopRunInMode(kCFRunLoopDefaultMode, time_frame-min, false);
    end = CFAbsoluteTimeGetCurrent();

    time_frame -= end-start;
    end = start = 0;
  }

  if (time_frame > 0) {
    struct timespec ts;

    ts.tv_sec  = (long)time_frame;
    ts.tv_nsec = (long)(time_frame * 1000000000.0);

    start = CFAbsoluteTimeGetCurrent();
    nanosleep(&ts, NULL);
    end = CFAbsoluteTimeGetCurrent();
  }

  return time_frame-(end-start);
}


/* Returns current time in microseconds */
unsigned int GetTimer()
{
  return (unsigned int)(CFAbsoluteTimeGetCurrent() * 1000000);
}  

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

/* Returns time spent between now and last call in seconds */
float GetRelativeTime()
{
  CFAbsoluteTime last_time = relative_time;
  relative_time = CFAbsoluteTimeGetCurrent();
  return (float)(relative_time - last_time);
}

/* Initialize timer, must be called at least once at start */
void InitTimer()
{
  GetRelativeTime();
}