1 /* $OpenBSD: input.c,v 1.10 2003/06/03 03:01:41 millert 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. Neither the name of the University nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 *
35 * @(#)input.c 8.1 (Berkeley) 5/31/93
36 */
37
38 /*
39 * Tetris input.
40 */
41
42 #include <sys/types.h>
43 #include <sys/time.h>
44
45 #include <errno.h>
46 #include <unistd.h>
47 #include <string.h>
48
49 #include "input.h"
50 #include "tetris.h"
51
52 /* return true iff the given timeval is positive */
53 #define TV_POS(tv) \
54 ((tv)->tv_sec > 0 || ((tv)->tv_sec == 0 && (tv)->tv_usec > 0))
55
56 /* subtract timeval `sub' from `res' */
57 #define TV_SUB(res, sub) \
58 (res)->tv_sec -= (sub)->tv_sec; \
59 (res)->tv_usec -= (sub)->tv_usec; \
60 if ((res)->tv_usec < 0) { \
61 (res)->tv_usec += 1000000; \
62 (res)->tv_sec--; \
63 }
64
65 /*
66 * Do a `read wait': select for reading from stdin, with timeout *tvp.
67 * On return, modify *tvp to reflect the amount of time spent waiting.
68 * It will be positive only if input appeared before the time ran out;
69 * otherwise it will be zero or perhaps negative.
70 *
71 * If tvp is nil, wait forever, but return if select is interrupted.
72 *
73 * Return 0 => no input, 1 => can read() from stdin
74 */
75 int
rwait(tvp)76 rwait(tvp)
77 struct timeval *tvp;
78 {
79 struct timeval starttv, endtv, *s;
80 fd_set fds;
81
82 #define NILTZ ((struct timezone *)0)
83
84 /*
85 * Someday, select() will do this for us.
86 * Just in case that day is now, and no one has
87 * changed this, we use a temporary.
88 */
89 if (tvp) {
90 (void) gettimeofday(&starttv, NILTZ);
91 endtv = *tvp;
92 s = &endtv;
93 } else
94 s = NULL;
95 again:
96 FD_ZERO(&fds);
97 FD_SET(STDIN_FILENO, &fds);
98 switch (select(STDIN_FILENO + 1, &fds, (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 */
126 void
tsleep()127 tsleep()
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 * getchar with timeout.
141 */
142 int
tgetchar()143 tgetchar()
144 {
145 static struct timeval timeleft;
146 char c;
147
148 /*
149 * Reset timeleft to fallrate whenever it is not positive.
150 * In any case, wait to see if there is any input. If so,
151 * take it, and update timeleft so that the next call to
152 * tgetchar() will not wait as long. If there is no input,
153 * make timeleft zero or negative, and return -1.
154 *
155 * Most of the hard work is done by rwait().
156 */
157 if (!TV_POS(&timeleft)) {
158 faster(); /* go faster */
159 timeleft.tv_sec = 0;
160 timeleft.tv_usec = fallrate;
161 }
162 if (!rwait(&timeleft))
163 return (-1);
164 if (read(0, &c, 1) != 1)
165 stop("end of file, help");
166 return ((int)(unsigned char)c);
167 }
168