1 /*	$NetBSD: input.c,v 1.11 2009/05/25 04:33:53 dholland 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. Neither the name of the University nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  *
34  *	@(#)input.c	8.1 (Berkeley) 5/31/93
35  */
36 
37 /*
38  * Tetris input.
39  */
40 
41 #include <sys/types.h>
42 #include <sys/time.h>
43 #include <sys/poll.h>
44 
45 #include <errno.h>
46 #include <unistd.h>
47 
48 #include "input.h"
49 #include "tetris.h"
50 
51 #ifndef INFTIM
52 # define INFTIM (-1)
53 #endif
54 
55 /* return true iff the given timeval is positive */
56 #define	TV_POS(tv) \
57 	((tv)->tv_sec > 0 || ((tv)->tv_sec == 0 && (tv)->tv_usec > 0))
58 
59 /* subtract timeval `sub' from `res' */
60 #define	TV_SUB(res, sub) \
61 	(res)->tv_sec -= (sub)->tv_sec; \
62 	(res)->tv_usec -= (sub)->tv_usec; \
63 	if ((res)->tv_usec < 0) { \
64 		(res)->tv_usec += 1000000; \
65 		(res)->tv_sec--; \
66 	}
67 
68 /*
69  * Do a `read wait': poll for reading from stdin, with timeout *tvp.
70  * On return, modify *tvp to reflect the amount of time spent waiting.
71  * It will be positive only if input appeared before the time ran out;
72  * otherwise it will be zero or perhaps negative.
73  *
74  * If tvp is nil, wait forever, but return if poll is interrupted.
75  *
76  * Return 0 => no input, 1 => can read() from stdin
77  */
78 int
79 rwait(struct timeval *tvp)
80 {
81 	struct pollfd set[1];
82 	struct timeval starttv, endtv;
83 	int timeout;
84 #define	NILTZ ((struct timezone *)0)
85 
86 	if (tvp) {
87 		(void) gettimeofday(&starttv, NILTZ);
88 		endtv = *tvp;
89 		timeout = tvp->tv_sec * 1000 + tvp->tv_usec / 1000;
90 	} else
91 		timeout = INFTIM;
92 again:
93 	set[0].fd = STDIN_FILENO;
94 	set[0].events = POLLIN;
95 	switch (poll(set, 1, timeout)) {
96 
97 	case -1:
98 		if (tvp == 0)
99 			return (-1);
100 		if (errno == EINTR)
101 			goto again;
102 		stop("poll failed, help");
103 		/* NOTREACHED */
104 
105 	case 0:	/* timed out */
106 		if (tvp) {
107 			tvp->tv_sec = 0;
108 			tvp->tv_usec = 0;
109 		}
110 		return (0);
111 	}
112 	if (tvp) {
113 		/* since there is input, we may not have timed out */
114 		(void) gettimeofday(&endtv, NILTZ);
115 		TV_SUB(&endtv, &starttv);
116 		TV_SUB(tvp, &endtv);	/* adjust *tvp by elapsed time */
117 	}
118 	return (1);
119 }
120 
121 /*
122  * `sleep' for the current turn time.
123  * Eat any input that might be available.
124  */
125 void
126 tsleep(void)
127 {
128 	struct timeval tv;
129 	char c;
130 
131 	tv.tv_sec = 0;
132 	tv.tv_usec = fallrate;
133 	while (TV_POS(&tv))
134 		if (rwait(&tv) && read(0, &c, 1) != 1)
135 			break;
136 }
137 
138 /*
139  * getchar with timeout.
140  */
141 int
142 tgetchar(void)
143 {
144 	static struct timeval timeleft;
145 	char c;
146 
147 	/*
148 	 * Reset timeleft to fallrate whenever it is not positive.
149 	 * In any case, wait to see if there is any input.  If so,
150 	 * take it, and update timeleft so that the next call to
151 	 * tgetchar() will not wait as long.  If there is no input,
152 	 * make timeleft zero or negative, and return -1.
153 	 *
154 	 * Most of the hard work is done by rwait().
155 	 */
156 	if (!TV_POS(&timeleft)) {
157 		faster();	/* go faster */
158 		timeleft.tv_sec = 0;
159 		timeleft.tv_usec = fallrate;
160 	}
161 	if (!rwait(&timeleft))
162 		return (-1);
163 	if (read(0, &c, 1) != 1)
164 		stop("end of file, help");
165 	return ((int)(unsigned char)c);
166 }