input.c revision 1.2 
1/*    $NetBSD: input.c,v 1.3 1996/02/06 22:47:33 jtc Exp $    */
2
3/*-
4 * Copyright (c) 1992, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Chris Torek and Darren F. Provine.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 *    must display the following acknowledgement:
20 *	This product includes software developed by the University of
21 *	California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 *    may be used to endorse or promote products derived from this software
24 *    without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 *	@(#)input.c	8.1 (Berkeley) 5/31/93
39 */
40
41/*
42 * Tetris input.
43 */
44
45#include <sys/types.h>
46#include <sys/time.h>
47
48#include <errno.h>
49#include <unistd.h>
50
51#include "input.h"
52#include "tetris.h"
53
54/* return true iff the given timeval is positive */
55#define	TV_POS(tv) \
56	((tv)->tv_sec > 0 || ((tv)->tv_sec == 0 && (tv)->tv_usec > 0))
57
58/* subtract timeval `sub' from `res' */
59#define	TV_SUB(res, sub) \
60	(res)->tv_sec -= (sub)->tv_sec; \
61	(res)->tv_usec -= (sub)->tv_usec; \
62	if ((res)->tv_usec < 0) { \
63		(res)->tv_usec += 1000000; \
64		(res)->tv_sec--; \
65	}
66
67/*
68 * Do a `read wait': select for reading from stdin, with timeout *tvp.
69 * On return, modify *tvp to reflect the amount of time spent waiting.
70 * It will be positive only if input appeared before the time ran out;
71 * otherwise it will be zero or perhaps negative.
72 *
73 * If tvp is nil, wait forever, but return if select is interrupted.
74 *
75 * Return 0 => no input, 1 => can read() from stdin
76 */
77int
78rwait(tvp)
79	register struct timeval *tvp;
80{
81	int i;
82	struct timeval starttv, endtv, *s;
83#define	NILTZ ((struct timezone *)0)
84
85	/*
86	 * Someday, select() will do this for us.
87	 * Just in case that day is now, and no one has
88	 * changed this, we use a temporary.
89	 */
90	if (tvp) {
91		(void) gettimeofday(&starttv, NILTZ);
92		endtv = *tvp;
93		s = &endtv;
94	} else
95		s = 0;
96again:
97	i = 1;
98	switch (select(1, (fd_set *)&i, (fd_set *)0, (fd_set *)0, s)) {
99
100	case -1:
101		if (tvp == 0)
102			return (-1);
103		if (errno == EINTR)
104			goto again;
105		stop("select failed, help");
106		/* NOTREACHED */
107
108	case 0:	/* timed out */
109		tvp->tv_sec = 0;
110		tvp->tv_usec = 0;
111		return (0);
112	}
113	if (tvp) {
114		/* since there is input, we may not have timed out */
115		(void) gettimeofday(&endtv, NILTZ);
116		TV_SUB(&endtv, &starttv);
117		TV_SUB(tvp, &endtv);	/* adjust *tvp by elapsed time */
118	}
119	return (1);
120}
121
122/*
123 * `sleep' for the current turn time (using select).
124 * Eat any input that might be available.
125 */
126void
127tsleep()
128{
129	struct timeval tv;
130	char c;
131
132	tv.tv_sec = 0;
133	tv.tv_usec = fallrate;
134	while (TV_POS(&tv))
135		if (rwait(&tv) && read(0, &c, 1) != 1)
136			break;
137}
138
139/*
140 * Eat up any input (used at end of game).
141 */
142void
143eat_input()
144{
145	struct timeval tv;
146	char c;
147
148	do {
149		tv.tv_sec = tv.tv_usec = 0;
150	} while (rwait(&tv) && read(0, &c, 1) == 1);
151}
152
153/*
154 * getchar with timeout.
155 */
156int
157tgetchar()
158{
159	static struct timeval timeleft;
160	char c;
161
162	/*
163	 * Reset timeleft to fallrate whenever it is not positive.
164	 * In any case, wait to see if there is any input.  If so,
165	 * take it, and update timeleft so that the next call to
166	 * tgetchar() will not wait as long.  If there is no input,
167	 * make timeleft zero or negative, and return -1.
168	 *
169	 * Most of the hard work is done by rwait().
170	 */
171	if (!TV_POS(&timeleft)) {
172		faster();	/* go faster */
173		timeleft.tv_sec = 0;
174		timeleft.tv_usec = fallrate;
175	}
176	if (!rwait(&timeleft))
177		return (-1);
178	if (read(0, &c, 1) != 1)
179		stop("end of file, help");
180	return ((int)(unsigned char)c);
181}
182