xref: /illumos-gate/usr/src/lib/libcurses/screen/napms.c (revision 9b9d39d2a32ff806d2431dbcc50968ef1e6d46b2)
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 1997 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 /*	Copyright (c) 1988 AT&T	*/
28 /*	  All Rights Reserved	*/
29 
30 /*
31  * University Copyright- Copyright (c) 1982, 1986, 1988
32  * The Regents of the University of California
33  * All Rights Reserved
34  *
35  * University Acknowledgment- Portions of this document are derived from
36  * software developed by the University of California, Berkeley, and its
37  * contributors.
38  */
39 
40 /*LINTLIBRARY*/
41 
42 #include	"curses_inc.h"
43 #include	<stdio.h>
44 #include	<sys/types.h>
45 #include	<poll.h>
46 
47 /*
48  * napms.  Sleep for ms milliseconds.  We don't expect a particularly good
49  * resolution - 60ths of a second is normal, 10ths might even be good enough,
50  * but the rest of the program thinks in ms because the unit of resolution
51  * varies from system to system.  (In some countries, it's 50ths, for example.)
52  * Vaxen running 4.2BSD and 3B's use 100ths.
53  *
54  * Here are some reasonable ways to get a good nap.
55  *
56  * (1) Use the poll() or select() system calls in SVr3 or Berkeley 4.2BSD.
57  *
58  * (2) Use the 1/10th second resolution wait in the System V tty driver.
59  *     It turns out this is hard to do - you need a tty line that is
60  *     always unused that you have read permission on to sleep on.
61  *
62  * (3) Install the ft (fast timer) device in your kernel.
63  *     This is a psuedo-device to which an ioctl will wait n ticks
64  *     and then send you an alarm.
65  *
66  * (4) Install the nap system call in your kernel.
67  *     This system call does a timeout for the requested number of ticks.
68  *
69  * (5) Write a routine that busy waits checking the time with ftime.
70  *     Ftime is not present on SYSV systems, and since this busy waits,
71  *     it will drag down response on your system.  But it works.
72  */
73 
74 int
75 napms(int ms)
76 {
77 	struct pollfd pollfd;
78 
79 	if (poll(&pollfd, 0L, ms) == -1)
80 		perror("poll");
81 	return (OK);
82 }
83