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/**
* @file timer.c
* @author Gertjan van den Burg
* @date January, 2014
* @brief Utility functions relating to time
*
* @details
* This file contains a simple function for calculating the time in seconds
* elapsed between two clock() calls. It also contains a function for
* generating a string of the current time, used in writing output files.
*/
#include <time.h>
#include "timer.h"
/**
* @brief Calculate the time between two clocks
*
* @param[in] s_time starting time
* @param[in] e_time end time
* @returns time elapsed in seconds
*/
double elapsed_time(clock_t s_time, clock_t e_time)
{
return ((double) (e_time - s_time))/((double) CLOCKS_PER_SEC);
}
/**
* @brief Get time string with UTC offset
*
* @details
* Create a string for the current system time. Include an offset of UTC for
* consistency. The format of the generated string is "DDD MMM D HH:MM:SS
* YYYY (UTC +HH:MM)", e.g. "Fri Aug 9, 12:34:56 2013 (UTC +02:00)".
*
* @param[in,out] buffer allocated string buffer, on exit contains
* formatted string
*
*/
void get_time_string(char *buffer)
{
int diff, hours, minutes;
char timestr[MAX_LINE_LENGTH];
time_t current_time, lt, gt;
struct tm *lclt;
// get current time (in epoch)
current_time = time(NULL);
if (current_time == ((time_t)-1)) {
fprintf(stderr, "Failed to compute the current time.\n");
return;
}
// convert time to local time and create a string
lclt = localtime(¤t_time);
strftime(timestr, MAX_LINE_LENGTH, "%c", lclt);
if (timestr == NULL) {
fprintf(stderr, "Failed to convert time to string.\n");
return;
}
// calculate the UTC offset including DST
lt = mktime(localtime(¤t_time));
gt = mktime(gmtime(¤t_time));
diff = -difftime(gt, lt);
hours = (diff/3600);
minutes = (diff%3600)/60;
if (lclt->tm_isdst == 1)
hours++;
sprintf(buffer, "%s (UTC %+03i:%02i)", timestr, hours, minutes);
}
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