input.c revision 1.17 
1/*	$OpenBSD: input.c,v 1.17 2016/01/10 13:35:10 mestre 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 <errno.h>
43#include <poll.h>
44#include <unistd.h>
45
46#include "input.h"
47#include "tetris.h"
48
49/* return true iff the given timeval is positive */
50#define	TV_POS(tv) \
51	((tv)->tv_sec > 0 || ((tv)->tv_sec == 0 && (tv)->tv_usec > 0))
52
53/* subtract timeval `sub' from `res' */
54#define	TV_SUB(res, sub) \
55	(res)->tv_sec -= (sub)->tv_sec; \
56	(res)->tv_usec -= (sub)->tv_usec; \
57	if ((res)->tv_usec < 0) { \
58		(res)->tv_usec += 1000000; \
59		(res)->tv_sec--; \
60	}
61
62/*
63 * Do a `read wait': poll for reading from stdin, with timeout *tvp.
64 * On return, modify *tvp to reflect the amount of time spent waiting.
65 * It will be positive only if input appeared before the time ran out;
66 * otherwise it will be zero or perhaps negative.
67 *
68 * If tvp is nil, wait forever, but return if poll is interrupted.
69 *
70 * Return 0 => no input, 1 => can read() from stdin
71 */
72int
73rwait(struct timeval *tvp)
74{
75	int	timo = INFTIM;
76	struct timeval starttv, endtv;
77	struct pollfd pfd[1];
78
79#define	NILTZ ((struct timezone *)0)
80
81	if (tvp) {
82		(void) gettimeofday(&starttv, NILTZ);
83		endtv = *tvp;
84		timo = endtv.tv_sec * 1000 + endtv.tv_usec / 1000;
85	}
86again:
87	pfd[0].fd = STDIN_FILENO;
88	pfd[0].events = POLLIN;
89	switch (poll(pfd, 1, timo)) {
90	case -1:
91		if (tvp == 0)
92			return (-1);
93		if (errno == EINTR)
94			goto again;
95		stop("poll failed, help");
96
97	case 0:	/* timed out */
98		tvp->tv_sec = 0;
99		tvp->tv_usec = 0;
100		return (0);
101	}
102	if (tvp) {
103		/* since there is input, we may not have timed out */
104		(void) gettimeofday(&endtv, NILTZ);
105		TV_SUB(&endtv, &starttv);
106		TV_SUB(tvp, &endtv);	/* adjust *tvp by elapsed time */
107	}
108	return (1);
109}
110
111/*
112 * `sleep' for the current turn time (using poll).
113 * Eat any input that might be available.
114 */
115void
116tsleep(void)
117{
118	struct timeval tv;
119	char c;
120
121	tv.tv_sec = 0;
122	tv.tv_usec = fallrate;
123	while (TV_POS(&tv))
124		if (rwait(&tv) && read(STDIN_FILENO, &c, 1) != 1)
125			break;
126}
127
128/*
129 * getchar with timeout.
130 */
131int
132tgetchar(void)
133{
134	static struct timeval timeleft;
135	char c;
136
137	/*
138	 * Reset timeleft to fallrate whenever it is not positive.
139	 * In any case, wait to see if there is any input.  If so,
140	 * take it, and update timeleft so that the next call to
141	 * tgetchar() will not wait as long.  If there is no input,
142	 * make timeleft zero or negative, and return -1.
143	 *
144	 * Most of the hard work is done by rwait().
145	 */
146	if (!TV_POS(&timeleft)) {
147		faster();	/* go faster */
148		timeleft.tv_sec = 0;
149		timeleft.tv_usec = fallrate;
150	}
151	if (!rwait(&timeleft))
152		return (-1);
153	if (read(STDIN_FILENO, &c, 1) != 1)
154		stop("end of file, help");
155	return ((int)(unsigned char)c);
156}
157