2 * Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
32 #include <machine/cpufunc.h>
33 #include "bootstrap.h"
36 static int bios_seconds(void);
39 * Return the BIOS time-of-day value.
41 * XXX uses undocumented BCD support from libstand.
47 unsigned char bios_time[6];
50 v86.addr = 0x1c; /* int 0x1c, function 0 */
52 v86.es = VTOPSEG(bios_time);
53 v86.ebx = VTOPOFF(bios_time);
56 hr = bcd2bin(bios_time[3]);
57 minute = bcd2bin(bios_time[4]);
58 sec = bcd2bin(bios_time[5]);
60 return (hr * 3600 + minute * 60 + sec);
64 * Return the time in seconds since the beginning of the day.
69 static time_t lasttime;
84 * Use the BIOS Wait function to pause for (period) microseconds.
86 * Resolution of this function is variable, but typically around
94 period = (period + 500) / 1000;
95 for( ; period != 0 ; period--)
96 for(i=800;i != 0; i--)
97 outb(0x5f,0); /* wait 600ns */