xref: /illumos-gate/usr/src/lib/libc/port/sys/time_util.c (revision 88b8d962)
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  * Copyright 2016 Joyent, Inc.
26  */
27 
28 #include <sys/types.h>
29 #include <time.h>
30 #include <errno.h>
31 
32 /*
33  * This function is blatently stolen from the kernel.
34  * See the dissertation in the comments preceding the
35  * hrt2ts() function in:
36  *	uts/common/os/timers.c
37  */
38 void
hrt2ts(hrtime_t hrt,timespec_t * tsp)39 hrt2ts(hrtime_t hrt, timespec_t *tsp)
40 {
41 #if defined(__amd64)
42 	tsp->tv_sec = hrt / NANOSEC;
43 	tsp->tv_nsec = hrt % NANOSEC;
44 #else
45 	uint32_t sec, nsec, tmp;
46 
47 	tmp = (uint32_t)(hrt >> 30);
48 	sec = tmp - (tmp >> 2);
49 	sec = tmp - (sec >> 5);
50 	sec = tmp + (sec >> 1);
51 	sec = tmp - (sec >> 6) + 7;
52 	sec = tmp - (sec >> 3);
53 	sec = tmp + (sec >> 1);
54 	sec = tmp + (sec >> 3);
55 	sec = tmp + (sec >> 4);
56 	tmp = (sec << 7) - sec - sec - sec;
57 	tmp = (tmp << 7) - tmp - tmp - tmp;
58 	tmp = (tmp << 7) - tmp - tmp - tmp;
59 	nsec = (uint32_t)hrt - (tmp << 9);
60 	while (nsec >= NANOSEC) {
61 		nsec -= NANOSEC;
62 		sec++;
63 	}
64 	tsp->tv_sec = (time_t)sec;
65 	tsp->tv_nsec = nsec;
66 #endif /* defined(__amd64) */
67 }
68 
69 /*
70  * Convert absolute time to relative time.
71  * All *timedwait() system call traps expect relative time.
72  */
73 void
abstime_to_reltime(clockid_t clock_id,const timespec_t * abstime,timespec_t * reltime)74 abstime_to_reltime(clockid_t clock_id, const timespec_t *abstime,
75     timespec_t *reltime)
76 {
77 	extern int __clock_gettime(clockid_t, timespec_t *);
78 	timespec_t now;
79 
80 	if (clock_id == CLOCK_HIGHRES)
81 		hrt2ts(gethrtime(), &now);
82 	else
83 		(void) __clock_gettime(clock_id, &now);
84 	if (abstime->tv_nsec >= now.tv_nsec) {
85 		reltime->tv_sec = abstime->tv_sec - now.tv_sec;
86 		reltime->tv_nsec = abstime->tv_nsec - now.tv_nsec;
87 	} else {
88 		reltime->tv_sec = abstime->tv_sec - now.tv_sec - 1;
89 		reltime->tv_nsec = abstime->tv_nsec - now.tv_nsec + NANOSEC;
90 	}
91 	/*
92 	 * If the absolute time has already passed,
93 	 * just set the relative time to zero.
94 	 */
95 	if (reltime->tv_sec < 0) {
96 		reltime->tv_sec = 0;
97 		reltime->tv_nsec = 0;
98 	}
99 	/*
100 	 * If the specified absolute time has a bad nanoseconds value,
101 	 * assign it to the relative time value.  If the interface
102 	 * attempts to sleep, the bad value will be detected then.
103 	 * The SUSV3 Posix spec is very clear that such detection
104 	 * should not happen until an attempt to sleep is made.
105 	 */
106 	if ((ulong_t)abstime->tv_nsec >= NANOSEC)
107 		reltime->tv_nsec = abstime->tv_nsec;
108 }
109