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Make microtime properly monotonic, with code derived from the /alpha

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implementation.
This commit is contained in:
bjh21 2001-05-14 23:45:39 +00:00
parent bdb6ea6ecc
commit f44b12db52
1 changed files with 41 additions and 10 deletions
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51
sys/arch/arm26/iobus/ioc.c
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@ -1,4 +1,4 @@
/* $NetBSD: ioc.c,v 1.10 2001/04/16 14:12:38 bjh21 Exp $ */
/* $NetBSD: ioc.c,v 1.11 2001/05/14 23:45:39 bjh21 Exp $ */
/*-
* Copyright (c) 1998, 1999, 2000 Ben Harris
@ -33,7 +33,7 @@
#include <sys/param.h>
__RCSID("$NetBSD: ioc.c,v 1.10 2001/04/16 14:12:38 bjh21 Exp $");
__RCSID("$NetBSD: ioc.c,v 1.11 2001/05/14 23:45:39 bjh21 Exp $");
#include <sys/device.h>
#include <sys/kernel.h>
@ -444,12 +444,15 @@ setstatclockrate(int hzrate)
}
void
microtime(struct timeval *tv)
microtime(struct timeval *tvp)
{
static struct timeval lasttime;
struct timeval t;
struct device *self;
struct ioc_softc *sc;
bus_space_tag_t bst;
bus_space_handle_t bsh;
long sec, usec;
int t0, s, intbefore, intafter;
KASSERT(the_ioc != NULL);
@ -461,7 +464,7 @@ microtime(struct timeval *tv)
s = splclock();
*tv = time;
t = time;
intbefore = ioc_irq_status(IOC_IRQ_TM0);
bus_space_write_1(bst, bsh, IOC_T0LATCH, 0);
@ -477,17 +480,45 @@ microtime(struct timeval *tv)
* Things are complicated by the fact that this could happen
* while we're trying to work out the time. We include some
* heuristics to spot this.
*
* NB: t0 counts down from t0_count to 0.
*/
if (intbefore || (intafter && t0 < t0_count / 2))
t0 -= t0_count;
tv->tv_usec += (t0_count - t0) / (IOC_TIMER_RATE / 1000000);
while (tv->tv_usec > 1000000) {
tv->tv_sec += 1;
tv->tv_usec -= 1000000;
t.tv_usec += (t0_count - t0) / (IOC_TIMER_RATE / 1000000);
while (t.tv_usec > 1000000) {
t.tv_usec -= 1000000;
t.tv_sec++;
}
/*
* Ordinarily, the current clock time is guaranteed to be later
* by at least one microsecond than the last time the clock was
* read. However, this rule applies only if the current time is
* within one second of the last time. Otherwise, the clock will
* (shudder) be set backward. The clock adjustment daemon or
* human equivalent is presumed to be correctly implemented and
* to set the clock backward only upon unavoidable crisis.
*/
sec = lasttime.tv_sec - t.tv_sec;
usec = lasttime.tv_usec - t.tv_usec;
if (usec < 0) {
usec += 1000000;
sec--;
}
if (sec == 0) {
t.tv_usec += usec + 1;
if (t.tv_usec >= 1000000) {
t.tv_usec -= 1000000;
t.tv_sec++;
}
}
lasttime = t;
*tvp = t;
}
void