/*

    mtr  --  a network diagnostic tool

    Copyright (C) 2016  Matt Kimball

    This program is free software; you can redistribute it and/or modify

    it under the terms of the GNU General Public License version 2 as

    published by the Free Software Foundation.

    This program is distributed in the hope that it will be useful,

    but WITHOUT ANY WARRANTY; without even the implied warranty of

    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License

    along with this program; if not, write to the Free Software

    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

#include "timeval.h"

/*

    Ensure that a timevalue has a microsecond value in the range

    [0.0, 1.0e6) microseconds by converting microseconds to full seconds.

*/

void normalize_timeval(

    struct timeval *timeval)

{

    int full_sec;

    /*

       If tv_usec has overflowed a full second, convert the overflow

       to tv_sec.

     */

    full_sec = timeval->tv_usec / 1000000;

    timeval->tv_sec += full_sec;

    timeval->tv_usec -= 1000000 * full_sec;

    /*  If tv_usec is negative, make it positive by rolling tv_sec back  */

    if (timeval->tv_usec < 0) {

        timeval->tv_sec--;

        timeval->tv_usec += 1000000;

    }

    /*  If the entire time value is negative, clamp to zero  */

    if (timeval->tv_sec < 0) {

        timeval->tv_sec = 0;

        timeval->tv_usec = 0;

    }

}

/*

    Compare two time values.  Return:

        -1 if a < b

         0 if a == b

         1 if a > b

*/

int compare_timeval(

    struct timeval a,

    struct timeval b)

{

    if (a.tv_sec > b.tv_sec) {

        return 1;

    }

    if (a.tv_sec < b.tv_sec) {

        return -1;

    }

    if (a.tv_usec > b.tv_usec) {

        return 1;

    }

    if (a.tv_usec < b.tv_usec) {

        return -1;

    }

    return 0;

}