1 /* $OpenBSD: input.c,v 1.19 2017/08/13 02:12:16 tedu 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/time.h>
43
44 #include <errno.h>
45 #include <poll.h>
46 #include <time.h>
47 #include <unistd.h>
48
49 #include "input.h"
50 #include "tetris.h"
51
52 /* return true iff the given timespec is positive */
53 #define TS_POS(ts) \
54 ((ts)->tv_sec > 0 || ((ts)->tv_sec == 0 && (ts)->tv_nsec > 0))
55
56 /*
57 * Do a `read wait': poll for reading from stdin, with timeout *limit.
58 * On return, subtract the time spent waiting from *limit.
59 * It will be positive only if input appeared before the time ran out;
60 * otherwise it will be zero or perhaps negative.
61 *
62 * If limit is NULL, wait forever, but return if poll is interrupted.
63 *
64 * Return 0 => no input, 1 => can read() from stdin, -1 => interrupted
65 */
66 int
rwait(struct timespec * limit)67 rwait(struct timespec *limit)
68 {
69 struct timespec start, end, elapsed;
70 struct pollfd pfd[1];
71
72 pfd[0].fd = STDIN_FILENO;
73 pfd[0].events = POLLIN;
74
75 if (limit != NULL)
76 clock_gettime(CLOCK_MONOTONIC, &start);
77 again:
78 switch (ppoll(pfd, 1, limit, NULL)) {
79 case -1:
80 if (limit == NULL)
81 return (-1);
82 if (errno == EINTR)
83 goto again;
84 stop("poll failed, help");
85 case 0: /* timed out */
86 timespecclear(limit);
87 return (0);
88 }
89 if (limit != NULL) {
90 /* we have input, so subtract the elapsed time from *limit */
91 clock_gettime(CLOCK_MONOTONIC, &end);
92 timespecsub(&end, &start, &elapsed);
93 timespecsub(limit, &elapsed, limit);
94 }
95 return (1);
96 }
97
98 /*
99 * `sleep' for the current turn time and eat any
100 * input that becomes available.
101 */
102 void
tsleep(void)103 tsleep(void)
104 {
105 struct timespec ts;
106 char c;
107
108 ts.tv_sec = 0;
109 ts.tv_nsec = fallrate;
110 while (TS_POS(&ts))
111 if (rwait(&ts) && read(STDIN_FILENO, &c, 1) != 1)
112 break;
113 }
114
115 /*
116 * getchar with timeout.
117 */
118 int
tgetchar(void)119 tgetchar(void)
120 {
121 static struct timespec timeleft;
122 char c;
123
124 /*
125 * Reset timeleft to fallrate whenever it is not positive.
126 * In any case, wait to see if there is any input. If so,
127 * take it, and update timeleft so that the next call to
128 * tgetchar() will not wait as long. If there is no input,
129 * make timeleft zero or negative, and return -1.
130 *
131 * Most of the hard work is done by rwait().
132 */
133 if (!TS_POS(&timeleft)) {
134 faster(); /* go faster */
135 timeleft.tv_sec = 0;
136 timeleft.tv_nsec = fallrate;
137 }
138 if (!rwait(&timeleft))
139 return (-1);
140 if (read(STDIN_FILENO, &c, 1) != 1)
141 stop("end of file, help");
142 return ((int)(unsigned char)c);
143 }
144