NetBSD/sys/kern/subr_time.c

162 lines
4.8 KiB
C

/* $NetBSD: subr_time.c,v 1.3 2007/12/22 00:35:32 yamt Exp $ */
/*
* 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.
* 3. 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_clock.c 8.5 (Berkeley) 1/21/94
* @(#)kern_time.c 8.4 (Berkeley) 5/26/95
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: subr_time.c,v 1.3 2007/12/22 00:35:32 yamt Exp $");
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/timex.h>
#include <sys/time.h>
#include <sys/timetc.h>
#include <sys/intr.h>
/*
* Compute number of hz until specified time. Used to compute second
* argument to callout_reset() from an absolute time.
*/
int
hzto(struct timeval *tvp)
{
struct timeval now, tv;
tv = *tvp; /* Don't modify original tvp. */
getmicrotime(&now);
timersub(&tv, &now, &tv);
return tvtohz(&tv);
}
/*
* Compute number of ticks in the specified amount of time.
*/
int
tvtohz(struct timeval *tv)
{
unsigned long ticks;
long sec, usec;
/*
* If the number of usecs in the whole seconds part of the time
* difference fits in a long, then the total number of usecs will
* fit in an unsigned long. Compute the total and convert it to
* ticks, rounding up and adding 1 to allow for the current tick
* to expire. Rounding also depends on unsigned long arithmetic
* to avoid overflow.
*
* Otherwise, if the number of ticks in the whole seconds part of
* the time difference fits in a long, then convert the parts to
* ticks separately and add, using similar rounding methods and
* overflow avoidance. This method would work in the previous
* case, but it is slightly slower and assumes that hz is integral.
*
* Otherwise, round the time difference down to the maximum
* representable value.
*
* If ints are 32-bit, then the maximum value for any timeout in
* 10ms ticks is 248 days.
*/
sec = tv->tv_sec;
usec = tv->tv_usec;
if (usec < 0) {
sec--;
usec += 1000000;
}
if (sec < 0 || (sec == 0 && usec <= 0)) {
/*
* Would expire now or in the past. Return 0 ticks.
* This is different from the legacy hzto() interface,
* and callers need to check for it.
*/
ticks = 0;
} else if (sec <= (LONG_MAX / 1000000))
ticks = (((sec * 1000000) + (unsigned long)usec + (tick - 1))
/ tick) + 1;
else if (sec <= (LONG_MAX / hz))
ticks = (sec * hz) +
(((unsigned long)usec + (tick - 1)) / tick) + 1;
else
ticks = LONG_MAX;
if (ticks > INT_MAX)
ticks = INT_MAX;
return ((int)ticks);
}
/*
* Compute number of ticks in the specified amount of time.
*/
int
tstohz(struct timespec *ts)
{
struct timeval tv;
/*
* usec has great enough resolution for hz, so convert to a
* timeval and use tvtohz() above.
*/
TIMESPEC_TO_TIMEVAL(&tv, ts);
return tvtohz(&tv);
}
/*
* Check that a proposed value to load into the .it_value or
* .it_interval part of an interval timer is acceptable, and
* fix it to have at least minimal value (i.e. if it is less
* than the resolution of the clock, round it up.)
*/
int
itimerfix(struct timeval *tv)
{
if (tv->tv_sec < 0 || tv->tv_usec < 0 || tv->tv_usec >= 1000000)
return (EINVAL);
if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick)
tv->tv_usec = tick;
return (0);
}
int
itimespecfix(struct timespec *ts)
{
if (ts->tv_sec < 0 || ts->tv_nsec < 0 || ts->tv_nsec >= 1000000000)
return (EINVAL);
if (ts->tv_sec == 0 && ts->tv_nsec != 0 && ts->tv_nsec < tick * 1000)
ts->tv_nsec = tick * 1000;
return (0);
}