Time Difference obtained in Linux, accurate to microseconds

 

The time required for calculating the FFT in software recently. The collected references are as follows:

# Include <stdio. h>
# Include <stdlib. h>/* contains the standard library header file */

# Include <sys/time. h>

Int main (INT argc, char ** argv)
{
Struct timeval start, stop, diff;
Gettimeofday (& START, 0 );
// Do what you want to do...
Gettimeofday (& stop, 0 );
Timeval_subtract (& diff, & START, & stop );
Printf ("Total time: % d microsecond \ n", diff. TV _usec );
}

/**
* Calculate the two time intervals to obtain the time difference.
* @ Param struct timeval * resule returns the calculated time.
* @ Param struct timeval * x the previous time to be calculated
* @ Param struct timeval * y the last time to be calculated
* Return-1 failure, 0 success
**/
Int timeval_subtract (struct timeval * result, struct timeval * X, struct timeval * Y)

{
Int nsec;

If (X-> TV _sec> Y-> TV _sec)
Return-1;

If (X-> TV _sec = Y-> TV _sec) & (X-> TV _usec> Y-> TV _usec ))
Return-1;

Result-> TV _sec = (Y-> TV _sec-x-> TV _sec );
Result-> TV _usec = (Y-> TV _usec-x-> TV _usec );

If (result-> TV _usec <0)
{
Result-> TV _sec --;
Result-> maid + = 1000000;
}

Return 0;
}

--------------------------------------------------
# Include <sys/time. h>
# Include <unistd. h>
Int gettimeofday (struct timeval * TV, struct timezone * tz );
Function: returns the current time in the structure specified by TV.
Struct timeval {
Long TV _sec; // second
Long TV _usec; // microseconds
};
Convert TV _usec to milliseconds.
Check the timezone structure.

Appendix:
-------------------------------------------------
How to Implement C language for obtaining system time in Linux
# Include <time. h> // header file of C Language
# Include <stdio. h> // I/O of C Language

Void main ()
{
Time_t now; // instantiate the time_t Structure
Struct TM * timenow; // instantiate the TM structure pointer
Time (& now );
// The time function reads the current time (International Standard Time is not Beijing time), and then transmits the value to now

Timenow = localtime (& now );
// The localtime function converts the time now obtained from time to the time in your computer (that is, the region you set)

Printf ("local time is % s \ n", asctime (timenow ));
// In the previous sentence, the asctime function converts the time into characters and outputs the time using the printf () function.
}

Note: time_t is a struct defined in time. h. The prototype of the TM struct is as follows:

Struct TM
{
Int tm_sec; // seconds 0-61
Int tm_min; // minutes 1-59
Int tm_hour; // hours 0-23
Int tm_mday; // day of the month 1-31
Int tm_mon; // months since Jan 0-11
Int tm_year; // years from 1900
Int tm_wday; // days since Sunday, 0-6
Int tm_yday; // days since Jan 1, 0-365
Int tm_isdst; // Daylight Saving Time indicator
};

 

 

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