time.c revision 55211 
1/*-
2 * Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
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.
13 *
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
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: head/sys/boot/i386/libi386/time.c 55211 1999-12-29 09:54:46Z msmith $
27 */
28
29#include <stand.h>
30#include <btxv86.h>
31
32/*
33 * Return the time in seconds since the beginning of the day.
34 *
35 * If we pass midnight, don't wrap back to 0.
36 *
37 * XXX uses undocumented BCD support from libstand.
38 */
39
40time_t
41time(time_t *t)
42{
43    static time_t	lasttime, now;
44    int			hr, min, sec;
45
46    v86.ctl = 0;
47    v86.addr = 0x1a;		/* int 0x1a, function 2 */
48    v86.eax = 0x0200;
49    v86int();
50
51    hr = bcd2bin((v86.ecx & 0xff00) >> 8);	/* hour in %ch */
52    min = bcd2bin(v86.ecx & 0xff);		/* minute in %cl */
53    sec = bcd2bin((v86.edx & 0xff00) >> 8);	/* second in %dh */
54
55    now = hr * 3600 + min * 60 + sec;
56    if (now < lasttime)
57	now += 24 * 3600;
58    lasttime = now;
59
60    if (t != NULL)
61	*t = now;
62    return(now);
63}
64
65/*
66 * Use the BIOS Wait function to pause for (period) microseconds.
67 *
68 * Resolution of this function is variable, but typically around
69 * 1ms.
70 */
71void
72delay(int period)
73{
74    v86.ctl = 0;
75    v86.addr = 0x15;		/* int 0x15, function 0x86 */
76    v86.eax = 0x8600;
77    v86.ecx = period >> 16;
78    v86.edx = period & 0xffff;
79    v86int();
80}
81