1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License").  You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22/*
23 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
24 * Use is subject to license terms.
25 */
26
27#pragma ident	"%Z%%M%	%I%	%E% SMI"
28
29#include <sys/types.h>
30#include <time.h>
31#include <errno.h>
32
33/*
34 * This function is blatently stolen from the kernel.
35 * See the dissertation in the comments preceding the
36 * hrt2ts() function in:
37 *	uts/common/os/timers.c
38 */
39void
40hrt2ts(hrtime_t hrt, timespec_t *tsp)
41{
42	uint32_t sec, nsec, tmp;
43
44	tmp = (uint32_t)(hrt >> 30);
45	sec = tmp - (tmp >> 2);
46	sec = tmp - (sec >> 5);
47	sec = tmp + (sec >> 1);
48	sec = tmp - (sec >> 6) + 7;
49	sec = tmp - (sec >> 3);
50	sec = tmp + (sec >> 1);
51	sec = tmp + (sec >> 3);
52	sec = tmp + (sec >> 4);
53	tmp = (sec << 7) - sec - sec - sec;
54	tmp = (tmp << 7) - tmp - tmp - tmp;
55	tmp = (tmp << 7) - tmp - tmp - tmp;
56	nsec = (uint32_t)hrt - (tmp << 9);
57	while (nsec >= NANOSEC) {
58		nsec -= NANOSEC;
59		sec++;
60	}
61	tsp->tv_sec = (time_t)sec;
62	tsp->tv_nsec = nsec;
63}
64
65/*
66 * Convert absolute time to relative time.
67 * All *timedwait() system call traps expect relative time.
68 */
69void
70abstime_to_reltime(clockid_t clock_id,
71	const timespec_t *abstime, timespec_t *reltime)
72{
73	extern int __clock_gettime(clockid_t, timespec_t *);
74	timespec_t now;
75
76	if (clock_id == CLOCK_HIGHRES)
77		hrt2ts(gethrtime(), &now);
78	else
79		(void) __clock_gettime(clock_id, &now);
80	if (abstime->tv_nsec >= now.tv_nsec) {
81		reltime->tv_sec = abstime->tv_sec - now.tv_sec;
82		reltime->tv_nsec = abstime->tv_nsec - now.tv_nsec;
83	} else {
84		reltime->tv_sec = abstime->tv_sec - now.tv_sec - 1;
85		reltime->tv_nsec = abstime->tv_nsec - now.tv_nsec + NANOSEC;
86	}
87	/*
88	 * If the absolute time has already passed,
89	 * just set the relative time to zero.
90	 */
91	if (reltime->tv_sec < 0) {
92		reltime->tv_sec = 0;
93		reltime->tv_nsec = 0;
94	}
95	/*
96	 * If the specified absolute time has a bad nanoseconds value,
97	 * assign it to the relative time value.  If the interface
98	 * attempts to sleep, the bad value will be detected then.
99	 * The SUSV3 Posix spec is very clear that such detection
100	 * should not happen until an attempt to sleep is made.
101	 */
102	if ((ulong_t)abstime->tv_nsec >= NANOSEC)
103		reltime->tv_nsec = abstime->tv_nsec;
104}
105