time.c revision 64187 
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 64187 2000-08-03 09:14:02Z jhb $
27 */
28
29#include <stand.h>
30#include <btxv86.h>
31#include "bootstrap.h"
32#include "libi386.h"
33
34/*
35 * Return the time in seconds since the beginning of the day.
36 *
37 * If we pass midnight, don't wrap back to 0.
38 *
39 * XXX uses undocumented BCD support from libstand.
40 */
41
42time_t
43time(time_t *t)
44{
45    static time_t	lasttime, now;
46    int			hr, minute, sec;
47
48    v86.ctl = 0;
49    v86.addr = 0x1a;		/* int 0x1a, function 2 */
50    v86.eax = 0x0200;
51    v86int();
52
53    hr = bcd2bin((v86.ecx & 0xff00) >> 8);	/* hour in %ch */
54    minute = bcd2bin(v86.ecx & 0xff);		/* minute in %cl */
55    sec = bcd2bin((v86.edx & 0xff00) >> 8);	/* second in %dh */
56
57    now = hr * 3600 + minute * 60 + sec;
58    if (now < lasttime)
59	now += 24 * 3600;
60    lasttime = now;
61
62    if (t != NULL)
63	*t = now;
64    return(now);
65}
66
67/*
68 * Use the BIOS Wait function to pause for (period) microseconds.
69 *
70 * Resolution of this function is variable, but typically around
71 * 1ms.
72 */
73void
74delay(int period)
75{
76    v86.ctl = 0;
77    v86.addr = 0x15;		/* int 0x15, function 0x86 */
78    v86.eax = 0x8600;
79    v86.ecx = period >> 16;
80    v86.edx = period & 0xffff;
81    v86int();
82}
83