/*-
 * Copyright (c) 1982, 1986, 1989, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)kern_time.c 8.1 (Berkeley) 6/10/93
 */
#include <sys/kernel.h>
#include <sys/time.h>

/*
 * ratecheck(): simple time-based rate-limit checking.
 */
int
ratecheck(struct timeval *lasttime, const struct timeval *mininterval)
{
        struct timeval tv, delta;
        int rv = 0;

        getmicrouptime(&tv);            /* NB: 10ms precision */
        delta = tv;
        timevalsub(&delta, lasttime);

        /*
         * check for 0,0 is so that the message will be seen at least once,
         * even if interval is huge.
         */
        if (timevalcmp(&delta, mininterval, >=) ||
                (lasttime->tv_sec == 0 && lasttime->tv_usec == 0)) {
                *lasttime = tv;
                rv = 1;
        }

        return (rv);
}

/*
 * ppsratecheck(): packets (or events) per second limitation.
 *
 * Return 0 if the limit is to be enforced (e.g. the caller
 * should drop a packet because of the rate limitation).
 *
 * maxpps of 0 always causes zero to be returned.  maxpps of -1
 * always causes 1 to be returned; this effectively defeats rate
 * limiting.
 *
 * Note that we maintain the struct timeval for compatibility
 * with other bsd systems.  We reuse the storage and just monitor
 * clock ticks for minimal overhead.
 */
int
ppsratecheck(struct timeval *lasttime, int *curpps, int maxpps)
{
        int now;

        /*
         * Reset the last time and counter if this is the first call
         * or more than a second has passed since the last update of
         * lasttime.
         */
        now = ticks;
        if (lasttime->tv_sec == 0 || (u_int)(now - lasttime->tv_sec) >= hz) {
                lasttime->tv_sec = now;
                *curpps = 1;
                return (maxpps != 0);
        } else {
                (*curpps)++;            /* NB: ignore potential overflow */
                return (maxpps < 0 || *curpps <= maxpps);
        }
}

static void
timevalfix(struct timeval *t1)
{

        if (t1->tv_usec < 0) {
                t1->tv_sec--;
                t1->tv_usec += 1000000;
        }
        if (t1->tv_usec >= 1000000) {
                t1->tv_sec++;
                t1->tv_usec -= 1000000;
        }
}

/*
 * Add and subtract routines for timevals.
 * N.B.: subtract routine doesn't deal with
 * results which are before the beginning,
 * it just gets very confused in this case.
 * Caveat emptor.
 */
void
timevaladd(struct timeval *t1, const struct timeval *t2)
{

        t1->tv_sec += t2->tv_sec;
        t1->tv_usec += t2->tv_usec;
        timevalfix(t1);
}

void
timevalsub(struct timeval *t1, const struct timeval *t2)
{

        t1->tv_sec -= t2->tv_sec;
        t1->tv_usec -= t2->tv_usec;
        timevalfix(t1);
}