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 /* return true iff the given timeval is positive */
52 #define	TV_POS(tv) \
53 	((tv)->tv_sec > 0 || ((tv)->tv_sec == 0 && (tv)->tv_usec > 0))
54 
55 /* subtract timeval `sub' from `res' */
56 #define	TV_SUB(res, sub) \
57 	(res)->tv_sec -= (sub)->tv_sec; \
58 	(res)->tv_usec -= (sub)->tv_usec; \
59 	if ((res)->tv_usec < 0) { \
60 		(res)->tv_usec += 1000000; \
61 		(res)->tv_sec--; \
62 	}
63 
64 /*
65  * Do a `read wait': poll for reading from stdin, with timeout *tvp.
66  * On return, modify *tvp to reflect the amount of time spent waiting.
67  * It will be positive only if input appeared before the time ran out;
68  * otherwise it will be zero or perhaps negative.
69  *
70  * If tvp is nil, wait forever, but return if poll is interrupted.
71  *
72  * Return 0 => no input, 1 => can read() from stdin
73  */
74 int
75 rwait(struct timeval *tvp)
76 {
77 	struct pollfd set[1];
78 	struct timeval starttv, endtv;
79 	int timeout;
80 #define	NILTZ ((struct timezone *)0)
81 
82 	if (tvp) {
83 		(void) gettimeofday(&starttv, NILTZ);
84 		endtv = *tvp;
85 		timeout = tvp->tv_sec * 1000 + tvp->tv_usec / 1000;
86 	} else
87 		timeout = INFTIM;
88 again:
89 	set[0].fd = STDIN_FILENO;
90 	set[0].events = POLLIN;
91 	switch (poll(set, 1, timeout)) {
92 
93 	case -1:
94 		if (tvp == 0)
95 			return (-1);
96 		if (errno == EINTR)
97 			goto again;
98 		stop("poll failed, help");
99 		/* NOTREACHED */
100 
101 	case 0:	/* timed out */
102 		if (tvp) {
103 			tvp->tv_sec = 0;
104 			tvp->tv_usec = 0;
105 		}
106 		return (0);
107 	}
108 	if (tvp) {
109 		/* since there is input, we may not have timed out */
110 		(void) gettimeofday(&endtv, NILTZ);
111 		TV_SUB(&endtv, &starttv);
112 		TV_SUB(tvp, &endtv);	/* adjust *tvp by elapsed time */
113 	}
114 	return (1);
115 }
116 
117 /*
118  * `sleep' for the current turn time.
119  * Eat any input that might be available.
120  */
121 void
122 tsleep(void)
123 {
124 	struct timeval tv;
125 	char c;
126 
127 	tv.tv_sec = 0;
128 	tv.tv_usec = fallrate;
129 	while (TV_POS(&tv))
130 		if (rwait(&tv) && read(0, &c, 1) != 1)
131 			break;
132 }
133 
134 /*
135  * getchar with timeout.
136  */
137 int
138 tgetchar(void)
139 {
140 	static struct timeval timeleft;
141 	char c;
142 
143 	/*
144 	 * Reset timeleft to fallrate whenever it is not positive.
145 	 * In any case, wait to see if there is any input.  If so,
146 	 * take it, and update timeleft so that the next call to
147 	 * tgetchar() will not wait as long.  If there is no input,
148 	 * make timeleft zero or negative, and return -1.
149 	 *
150 	 * Most of the hard work is done by rwait().
151 	 */
152 	if (!TV_POS(&timeleft)) {
153 		faster();	/* go faster */
154 		timeleft.tv_sec = 0;
155 		timeleft.tv_usec = fallrate;
156 	}
157 	if (!rwait(&timeleft))
158 		return (-1);
159 	if (read(0, &c, 1) != 1)
160 		stop("end of file, help");
161 	return ((int)(unsigned char)c);
162 }