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Full Discussion: the problem of gettimeofday
Top Forums Programming the problem of gettimeofday Post 302220150 by dophine on Thursday 31st of July 2008 02:43:08 AM
Old 07-31-2008
the problem of gettimeofday
Hi all,

I just wrote a small problem to check gettimeofday in a multi-cores environment.

Code:
int timediff(double fTimeQvs, double fTimeTcp)
{
        int iTimeDiff;
        iTimeDiff = (((((int)fTimeQvs)/10000) - (((int)fTimeTcp)/10000)) * 3600) * 1000000;
        iTimeDiff += ((((((int)fTimeQvs)/100)%100) - ((((int)fTimeTcp)/100)%100)) * 60) * 1000000;
        iTimeDiff += ((((int)fTimeQvs)%100) - (((int)fTimeTcp)%100)) * 1000000;
        iTimeDiff += (((long long)(fTimeQvs*1000000))%1000000) - (((long long)(fTimeTcp*1000000))%1000000);

    return iTimeDiff;
}

int main()
{
        struct timeval cur;
        gettimeofday(&cur, 0);

        for(;;)
        {
                struct timeval new_time;
                gettimeofday(&new_time, 0);

                double diff = difftime(new_time.tv_sec,cur.tv_sec);
                if(diff > 1.0)
                        printf("Big:%ld.%ld,%ld.%ld,%lf\n",new_time.tv_sec,new_time.tv_sec, cur.tv_sec,cur.tv_usec,diff);
                else if(diff < 0.0)
                        printf("Small::%ld.%ld,%ld.%ld,%lf\n",new_time.tv_sec,new_time.tv_usec, cur.tv_sec,cur.tv_usec,diff);
                cur.tv_sec = new_time.tv_sec;
        }
        return 0;
}

Here is the result:
Small::1217485404.98014,1217489802.813903,-4398.000000
Big:1217489802.1217489802,1217485404.813903,4398.000000
Small::1217485404.99014,1217489802.813903,-4398.000000
Big:1217489802.1217489802,1217485404.813903,4398.000000
Small::1217485404.100014,1217489802.813903,-4398.000000
Big:1217489802.1217489802,1217485404.813903,4398.000000
Small::1217485404.101013,1217489802.813903,-4398.000000
Big:1217489802.1217489802,1217485404.813903,4398.000000
Small::1217485404.102014,1217489802.813903,-4398.000000
Big:1217489802.1217489802,1217485404.813903,4398.000000
Small::1217485404.103014,1217489802.813903,-4398.000000
Big:1217489802.1217489802,1217485404.813903,4398.000000
Small::1217485404.104014,1217489802.813903,-4398.000000
Big:1217489802.1217489802,1217485404.813903,4398.000000
Small::1217485404.105014,1217489802.813903,-4398.000000
Big:1217489802.1217489802,1217485404.813903,4398.000000
Small::1217485404.106014,1217489802.813903,-4398.000000
Big:1217489802.1217489802,1217485404.813903,4398.000000
Small::1217485404.107013,1217489802.813903,-4398.000000
Big:1217489802.1217489802,1217485404.813903,4398.000000
Small::1217485404.108013,1217489802.813903,-4398.000000
Big:1217489802.1217489802,1217485404.813903,4398.000000
Small::1217485404.109013,1217489802.813903,-4398.000000
Big:1217489802.1217489802,1217485404.813903,4398.000000
Small::1217485404.110014,1217489802.813903,-4398.000000
Big:1217489802.1217489802,1217485404.813903,4398.000000
Small::1217485404.111014,1217489802.813903,-4398.000000
Big:1217489802.1217489802,1217485404.813903,4398.000000
Small::1217485404.112014,1217489802.813903,-4398.000000
Big:1217489802.1217489802,1217485404.813903,4398.000000
Small::1217485404.113014,1217489802.813903,-4398.000000
Big:1217489802.1217489802,1217485404.813903,4398.000000
Small::1217485404.114014,1217489802.813903,-4398.000000

so is there any way to overcome it?
 

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LEARN ABOUT DEBIAN

input

INPUT(5)							File Formats Manual							  INPUT(5)

NAME

       input - input data file format

DESCRIPTION

       This  manual  page  describes  the  output format of the file created by the Yagi-Uda project input or first programs. The file is an ASCII
       file, so can be edited manually if required. It is read by yagi or optimise.  The program optimise also creates the same file format.

       NOTES
       FREQUENCY
       MIN_FREQUENCY
       MAX_FREQUENCY
       STEP_FREQUENCY
       ELEMENTS
       DRIVEN
       PARASITIC
       ANGULAR_STEP
       DATA_DRIVEN
       DATA_PARASITIC

       The
       #
       is used as a comment.

       A typical file, for an antenna designed for the 2m amateur band (144-146
       MHz) might be as shown below. Note:
       1) Reflector is at position 0.0
       2) All elements lengths/positions are in m.

       NOTES This line can be up to 400 characters.
       FREQUENCY 145.000000
       MIN_FREQUENCY 144.000000
       MAX_FREQUENCY 146.000000
       STEP_FREQUENCY 0.100000
       ELEMENTS 10
       DRIVEN 1
       PARASITIC 9
       ANGULAR_STEP   180.000000
       #DATA_DRIVEN x y length	diameter voltage phase
       DATA_DRIVEN  0.30993 0.000000 1.002492 0.0063000000000000 1.000000 0.000000
       # DATA_PARASITIC x y length  diameter
       DATA_PARASITIC
	  0.00000    0.00000	1.01902    0.00630
	  0.49859    0.00000	0.95551    0.00630
	  1.07338    0.00000	0.93595    0.00630
	  1.81020    0.00000	0.92050    0.00630
	  2.58152    0.00000	0.91322    0.00630
	  3.30390    0.00000	0.91243    0.00630
	  4.03692    0.00000	0.90423    0.00630
	  4.64108    0.00000	0.89081    0.00630
	  5.37418    0.00000	0.83912    0.00630

FILES

	    filename				ASCII description of antenna.	    filename.out			binary file

SEE ALSO

       yagi(1), output(1), input(1), optimise(1), first(1) and yagi(5).

AUTHORS

       Dr. David Kirkby G8WRB (david.kirkby@onetel.net), with help with converting to DOS from Dr. Joe Mack NA3T (mack@fcrfv2.ncifcrf.gov).

Yagi version 1.16						 24th October 2000							  INPUT(5)
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