/*! \file timer.c
 *  \brief various timer functions
 *  compile with -lrt -lm
 *  run from root
 */
/* (non-Doxygen)
 *       Revision:  none
 *       Compiler:  gcc
 *
 *         Author:  kuv (), ganqqwerty@bk.ru
 *        Company:  SIC ETU
 *
 * =====================================================================================
 */

#include  <stdio.h>
#include  <time.h>
#include  <stdlib.h>
#include  <math.h>

int main ()
{
  //===simple operations with time===
  //current real time:
  time_t seconds = time(0);
  struct tm* currentTime = gmtime(&seconds);
 
  printf("%s", "Current time: \n");
  //it's much easy and better that parsing by hands:
  printf("%s", asctime(currentTime));

  struct tm* futureTime = malloc(sizeof (struct tm));
  futureTime->tm_sec = 30;         /* seconds */
  futureTime->tm_min = 43;         /* minutes */
  futureTime->tm_hour = 22;        /* hours */
  futureTime->tm_mday = 20 ;        /* day of the month */
  futureTime->tm_mon = 1;         /* month */
  futureTime->tm_year = 112;        /* year */

  //let's try to change this pretty REAL time >:-]
  struct timespec futureTp;
  futureTp.tv_sec =   mktime(futureTime);
  if (clock_settime(CLOCK_REALTIME,&futureTp))
    printf("%s","Sorry, you are not root and you can't change calendar time.\n");

  //checking results: 
  struct timespec checkTp;
  clock_gettime(CLOCK_REALTIME, &checkTp);
  time_t newSeconds = checkTp.tv_sec;
  struct tm* newCurrentTime = gmtime(&newSeconds);
  printf("%s", "Changed time: \n");
  printf("%s", asctime (newCurrentTime));  

  //===how much time do functions take?===
  int howMuchTimes = 100500000;

  // in seconds, using time(): 
  time_t beginTime, endTime;
  time(&beginTime);
  int i;
  for (i=0; i!=howMuchTimes; i++)
    sin(i);
  time(&endTime);
  double diff = difftime(endTime, beginTime);
  printf("%d sin in seconds : %.2lf  \n", howMuchTimes ,  diff);

  //in mseconds using clock_gettime:
  struct timespec beginNanoTime, endNanoTime;
  clock_gettime(CLOCK_REALTIME, &beginNanoTime);
  for (i=0; i!=howMuchTimes; i++)
    sin(i);
  clock_gettime(CLOCK_REALTIME, &endNanoTime);
  double mSecDiff = (endNanoTime.tv_sec-beginNanoTime.tv_sec)*1000+fabs((endNanoTime.tv_nsec-beginNanoTime.tv_nsec)/1000000);
  printf("%.5lf \n ", mSecDiff);

 }