time.c revision 40209 
1/*
2 * mjs copyright
3 */
4
5#include <stand.h>
6#include <btxv86.h>
7
8/*
9 * Return the time in seconds since the beginning of the day.
10 *
11 * If we pass midnight, don't wrap back to 0.
12 *
13 * XXX uses undocumented BCD support from libstand.
14 */
15
16time_t
17time(time_t *t)
18{
19    static time_t	lasttime, now;
20    int			hr, min, sec;
21
22    v86.ctl = 0;
23    v86.addr = 0x1a;		/* int 0x1a, function 2 */
24    v86.eax = 0x0200;
25    v86int();
26
27    hr = bcd2bin((v86.ecx & 0xff00) >> 8);	/* hour in %ch */
28    min = bcd2bin(v86.ecx & 0xff);		/* minute in %cl */
29    sec = bcd2bin((v86.edx & 0xff00) >> 8);	/* second in %dh */
30
31    now = hr * 3600 + min * 60 + sec;
32    if (now < lasttime)
33	now += 24 * 3600;
34    lasttime = now;
35
36    if (t != NULL)
37	*t = now;
38    return(now);
39}
40
41/*
42 * Use the BIOS Wait function to pause for (period) microseconds.
43 *
44 * Resolution of this function is variable, but typically around
45 * 1ms.
46 */
47void
48delay(int period)
49{
50    v86.ctl = 0;
51    v86.addr = 0x15;		/* int 0x15, function 0x86 */
52    v86.eax = 0x8600;
53    v86.ecx = period >> 16;
54    v86.edx = period & 0xffff;
55    v86int();
56}
57