time.c revision 199767f8919635c4928607450d9e0abb932109ce
/*-
* Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
* 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
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*/
__FBSDID("$FreeBSD$");
#include <stand.h>
#include <btxv86.h>
#include "bootstrap.h"
#include "libi386.h"
static int bios_seconds(void);
/*
* Return the BIOS time-of-day value.
*
* XXX uses undocumented BCD support from libstand.
*/
static int
bios_seconds(void)
{
v86int();
}
/*
* Return the time in seconds since the beginning of the day.
*
* Some BIOSes (notably qemu) don't correctly read the RTC
* registers in an atomic way, sometimes returning bogus values.
* Therefore we "debounce" the reading by accepting it only when
* we got 8 identical values in succession.
*
* If we pass midnight, don't wrap back to 0.
*/
{
check = bios_seconds();
do {
check = bios_seconds();
same = 0;
if (t != NULL)
*t = now;
return(now);
}
/*
* Use the BIOS Wait function to pause for (period) microseconds.
*
* Resolution of this function is variable, but typically around
* 1ms.
*/
void
{
v86int();
}