input.c revision 1.13 
1/*	$OpenBSD: input.c,v 1.13 2014/11/03 22:14:54 deraadt 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 <poll.h>
48#include <string.h>
49
50#include "input.h"
51#include "tetris.h"
52
53/* return true iff the given timeval is positive */
54#define	TV_POS(tv) \
55	((tv)->tv_sec > 0 || ((tv)->tv_sec == 0 && (tv)->tv_usec > 0))
56
57/* subtract timeval `sub' from `res' */
58#define	TV_SUB(res, sub) \
59	(res)->tv_sec -= (sub)->tv_sec; \
60	(res)->tv_usec -= (sub)->tv_usec; \
61	if ((res)->tv_usec < 0) { \
62		(res)->tv_usec += 1000000; \
63		(res)->tv_sec--; \
64	}
65
66/*
67 * Do a `read wait': select for reading from stdin, with timeout *tvp.
68 * On return, modify *tvp to reflect the amount of time spent waiting.
69 * It will be positive only if input appeared before the time ran out;
70 * otherwise it will be zero or perhaps negative.
71 *
72 * If tvp is nil, wait forever, but return if select is interrupted.
73 *
74 * Return 0 => no input, 1 => can read() from stdin
75 */
76int
77rwait(struct timeval *tvp)
78{
79	struct timeval starttv, endtv, *s;
80	struct pollfd pfd[1];
81
82#define	NILTZ ((struct timezone *)0)
83
84	if (tvp) {
85		(void) gettimeofday(&starttv, NILTZ);
86		endtv = *tvp;
87		s = &endtv;
88	} else
89		s = NULL;
90again:
91	pfd[0].fd = STDIN_FILENO;
92	pfd[0].events = POLLIN;
93	switch (poll(pfd, 1, s->tv_sec * 1000 + s->tv_usec / 1000)) {
94
95	case -1:
96		if (tvp == 0)
97			return (-1);
98		if (errno == EINTR)
99			goto again;
100		stop("select failed, help");
101		/* NOTREACHED */
102
103	case 0:	/* timed out */
104		tvp->tv_sec = 0;
105		tvp->tv_usec = 0;
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 (using select).
119 * Eat any input that might be available.
120 */
121void
122tsleep(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(STDIN_FILENO, &c, 1) != 1)
131			break;
132}
133
134/*
135 * getchar with timeout.
136 */
137int
138tgetchar(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(STDIN_FILENO, &c, 1) != 1)
160		stop("end of file, help");
161	return ((int)(unsigned char)c);
162}
163