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/* nstime.c
* Routines for manipulating nstime_t structures
*
* Copyright (c) 2005 MX Telecom Ltd. <richardv@mxtelecom.com>
*
* $Id$
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@ethereal.com>
* Copyright 1998 Gerald Combs
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
*/
#include "nstime.h"
/* this is #defined so that we can clearly see that we have the right number of
zeros, rather than as a guard against the number of nanoseconds in a second
changing ;) */
#define NS_PER_S 1000000000
/*
* function: get_timedelta
* delta = b - a
*/
void get_timedelta(nstime_t *delta, const nstime_t *b, const nstime_t *a )
{
if (b->secs == a->secs) {
/* The seconds part of b is the same as the seconds part of a, so if
the nanoseconds part of the first time is less than the nanoseconds
part of a, b is before a. The nanoseconds part of the delta should
just be the difference between the nanoseconds part of b and the
nanoseconds part of a; don't adjust the seconds part of the delta,
as it's OK if the nanoseconds part is negative, and an overflow
can never result. */
delta->secs = 0;
delta->nsecs = b->nsecs - a->nsecs;
} else if (b->secs <= a->secs) {
/* The seconds part of b is less than the seconds part of a, so b is
before a.
Both the "seconds" and "nanoseconds" value of the delta
should have the same sign, so if the difference between the
nanoseconds values would be *positive*, subtract 1,000,000,000
from it, and add one to the seconds value. */
delta->secs = b->secs - a->secs;
delta->nsecs = b->nsecs - a->nsecs;
if(delta->nsecs > 0) {
delta->nsecs -= NS_PER_S;
delta->secs ++;
}
} else {
delta->secs = b->secs - a->secs;
delta->nsecs = b->nsecs - a->nsecs;
if(delta->nsecs < 0) {
delta->nsecs += NS_PER_S;
delta->secs --;
}
}
}
/*
* function: get_timesum
* sum = a + b
*/
void get_timesum(nstime_t *sum, const nstime_t *a, const nstime_t *b)
{
sum->secs = a->secs + b->secs;
sum->nsecs = a->nsecs + b->nsecs;
if(sum->nsecs>=NS_PER_S || (sum->nsecs>0 && sum->secs<0)){
sum->nsecs-=NS_PER_S;
sum->secs++;
} else if(sum->nsecs<=-NS_PER_S || (sum->nsecs<0 && sum->secs>0)) {
sum->nsecs+=NS_PER_S;
sum->secs--;
}
}
/*
* function: nstime_to_msec
* converts nstime to double, time base is milli seconds
*/
double nstime_to_msec(const nstime_t *time)
{
return ((double)time->secs*1000 + (double)time->nsecs/1000000);
}
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