input.c revision 1.7 
1/*	$OpenBSD: input.c,v 1.7 2001/09/27 08:37:33 deraadt Exp $	*/
2/*    $NetBSD: input.c,v 1.3 1996/02/06 22:47:33 jtc Exp $    */
3
4/*-
5 * Copyright (c) 1992, 1993
6 *	The Regents of the University of California.  All rights reserved.
7 *
8 * This code is derived from software contributed to Berkeley by
9 * Chris Torek and Darren F. Provine.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 * 3. All advertising materials mentioning features or use of this software
20 *    must display the following acknowledgement:
21 *	This product includes software developed by the University of
22 *	California, Berkeley and its contributors.
23 * 4. Neither the name of the University nor the names of its contributors
24 *    may be used to endorse or promote products derived from this software
25 *    without specific prior written permission.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37 * SUCH DAMAGE.
38 *
39 *	@(#)input.c	8.1 (Berkeley) 5/31/93
40 */
41
42/*
43 * Tetris input.
44 */
45
46#include <sys/types.h>
47#include <sys/time.h>
48
49#include <errno.h>
50#include <unistd.h>
51#include <string.h>
52
53#include "input.h"
54#include "tetris.h"
55
56/* return true iff the given timeval is positive */
57#define	TV_POS(tv) \
58	((tv)->tv_sec > 0 || ((tv)->tv_sec == 0 && (tv)->tv_usec > 0))
59
60/* subtract timeval `sub' from `res' */
61#define	TV_SUB(res, sub) \
62	(res)->tv_sec -= (sub)->tv_sec; \
63	(res)->tv_usec -= (sub)->tv_usec; \
64	if ((res)->tv_usec < 0) { \
65		(res)->tv_usec += 1000000; \
66		(res)->tv_sec--; \
67	}
68
69/*
70 * Do a `read wait': select for reading from stdin, with timeout *tvp.
71 * On return, modify *tvp to reflect the amount of time spent waiting.
72 * It will be positive only if input appeared before the time ran out;
73 * otherwise it will be zero or perhaps negative.
74 *
75 * If tvp is nil, wait forever, but return if select is interrupted.
76 *
77 * Return 0 => no input, 1 => can read() from stdin
78 */
79int
80rwait(tvp)
81	register struct timeval *tvp;
82{
83	int i;
84	struct timeval starttv, endtv, *s;
85	fd_set fds;
86
87#define	NILTZ ((struct timezone *)0)
88
89	/*
90	 * Someday, select() will do this for us.
91	 * Just in case that day is now, and no one has
92	 * changed this, we use a temporary.
93	 */
94	if (tvp) {
95		(void) gettimeofday(&starttv, NILTZ);
96		endtv = *tvp;
97		s = &endtv;
98	} else
99		s = NULL;
100again:
101	FD_ZERO(&fds);
102	FD_SET(STDIN_FILENO, &fds);
103	switch (select(STDIN_FILENO + 1, &fds, (fd_set *)0, (fd_set *)0, s)) {
104
105	case -1:
106		if (tvp == 0)
107			return (-1);
108		if (errno == EINTR)
109			goto again;
110		stop("select failed, help");
111		/* NOTREACHED */
112
113	case 0:	/* timed out */
114		tvp->tv_sec = 0;
115		tvp->tv_usec = 0;
116		return (0);
117	}
118	if (tvp) {
119		/* since there is input, we may not have timed out */
120		(void) gettimeofday(&endtv, NILTZ);
121		TV_SUB(&endtv, &starttv);
122		TV_SUB(tvp, &endtv);	/* adjust *tvp by elapsed time */
123	}
124	return (1);
125}
126
127/*
128 * `sleep' for the current turn time (using select).
129 * Eat any input that might be available.
130 */
131void
132tsleep()
133{
134	struct timeval tv;
135	char c;
136
137	tv.tv_sec = 0;
138	tv.tv_usec = fallrate;
139	while (TV_POS(&tv))
140		if (rwait(&tv) && read(0, &c, 1) != 1)
141			break;
142}
143
144/*
145 * getchar with timeout.
146 */
147int
148tgetchar()
149{
150	static struct timeval timeleft;
151	char c;
152
153	/*
154	 * Reset timeleft to fallrate whenever it is not positive.
155	 * In any case, wait to see if there is any input.  If so,
156	 * take it, and update timeleft so that the next call to
157	 * tgetchar() will not wait as long.  If there is no input,
158	 * make timeleft zero or negative, and return -1.
159	 *
160	 * Most of the hard work is done by rwait().
161	 */
162	if (!TV_POS(&timeleft)) {
163		faster();	/* go faster */
164		timeleft.tv_sec = 0;
165		timeleft.tv_usec = fallrate;
166	}
167	if (!rwait(&timeleft))
168		return (-1);
169	if (read(0, &c, 1) != 1)
170		stop("end of file, help");
171	return ((int)(unsigned char)c);
172}
173