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      1 /*
      2  * util/timeval_func.c - helpers to work with struct timeval values.
      3  *
      4  * Copyright (c) 2023, NLnet Labs. All rights reserved.
      5  *
      6  * This software is open source.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  *
     12  * Redistributions of source code must retain the above copyright notice,
     13  * this list of conditions and the following disclaimer.
     14  *
     15  * Redistributions in binary form must reproduce the above copyright notice,
     16  * this list of conditions and the following disclaimer in the documentation
     17  * and/or other materials provided with the distribution.
     18  *
     19  * Neither the name of the NLNET LABS nor the names of its contributors may
     20  * be used to endorse or promote products derived from this software without
     21  * specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     24  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     25  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     26  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     27  * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     28  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
     29  * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     30  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
     31  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
     32  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
     33  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     34  */
     35 
     36 /**
     37  * \file
     38  *
     39  * This file contains helpers to manipulate struct timeval values.
     40  */
     41 
     42 #include "config.h"
     43 #include "timeval_func.h"
     44 
     45 /** subtract timers and the values do not overflow or become negative */
     46 void
     47 timeval_subtract(struct timeval* d, const struct timeval* end, const struct timeval* start)
     48 {
     49 #ifndef S_SPLINT_S
     50 	time_t end_usec = end->tv_usec;
     51 	d->tv_sec = end->tv_sec - start->tv_sec;
     52 	if(end_usec < start->tv_usec) {
     53 		end_usec += 1000000;
     54 		d->tv_sec--;
     55 	}
     56 	d->tv_usec = end_usec - start->tv_usec;
     57 #endif
     58 }
     59 
     60 /** add timers and the values do not overflow or become negative */
     61 void
     62 timeval_add(struct timeval* d, const struct timeval* add)
     63 {
     64 #ifndef S_SPLINT_S
     65 	d->tv_sec += add->tv_sec;
     66 	d->tv_usec += add->tv_usec;
     67 	if(d->tv_usec >= 1000000 ) {
     68 		d->tv_usec -= 1000000;
     69 		d->tv_sec++;
     70 	}
     71 #endif
     72 }
     73 
     74 /** divide sum of timers to get average */
     75 void
     76 timeval_divide(struct timeval* avg, const struct timeval* sum, long long d)
     77 {
     78 #ifndef S_SPLINT_S
     79 	long long leftover;
     80 	if(d <= 0) {
     81 		avg->tv_sec = 0;
     82 		avg->tv_usec = 0;
     83 		return;
     84 	}
     85 	avg->tv_sec = sum->tv_sec / d;
     86 	avg->tv_usec = sum->tv_usec / d;
     87 	/* handle fraction from seconds divide */
     88 	leftover = sum->tv_sec - avg->tv_sec*d;
     89 	if(leftover <= 0)
     90 		leftover = 0;
     91 	avg->tv_usec += (((long long)leftover)*((long long)1000000))/d;
     92 	if(avg->tv_sec < 0)
     93 		avg->tv_sec = 0;
     94 	if(avg->tv_usec < 0)
     95 		avg->tv_usec = 0;
     96 #endif
     97 }
     98 
     99 /** histogram compare of time values */
    100 int
    101 timeval_smaller(const struct timeval* x, const struct timeval* y)
    102 {
    103 #ifndef S_SPLINT_S
    104 	if(x->tv_sec < y->tv_sec)
    105 		return 1;
    106 	else if(x->tv_sec == y->tv_sec) {
    107 		if(x->tv_usec <= y->tv_usec)
    108 			return 1;
    109 		else	return 0;
    110 	}
    111 	else	return 0;
    112 #endif
    113 }
    114