tetris/input.c

   1 /*      $NetBSD: input.c,v 1.6 2002/09/19 21:12:10 mycroft 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. All advertising materials mentioning features or use of this software
  19  *    must display the following acknowledgement:
  20  *      This product includes software developed by the University of
  21  *      California, Berkeley and its contributors.
  22  * 4. Neither the name of the University nor the names of its contributors
  23  *    may be used to endorse or promote products derived from this software
  24  *    without specific prior written permission.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  36  * SUCH DAMAGE.
  37  *
  38  *      @(#)input.c     8.1 (Berkeley) 5/31/93
  39  */
  40
  41 /*
  42  * Tetris input.
  43  */
  44
  45 #include <sys/types.h>
  46 #include <sys/time.h>
  47 #include <sys/poll.h>
  48
  49 #include <errno.h>
  50 #include <unistd.h>
  51
  52 #include "input.h"
  53 #include "tetris.h"
  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': select 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 select is interrupted.
  75  *
  76  * Return 0 => no input, 1 => can read() from stdin
  77  */
  78 int
  79 rwait(tvp)
  80         struct timeval *tvp;
  81 {
  82         struct pollfd set[1];
  83         struct timeval starttv, endtv, *s;
  84 #define NILTZ ((struct timezone *)0)
  85
  86         /*
  87          * Someday, select() will do this for us.
  88          * Just in case that day is now, and no one has
  89          * changed this, we use a temporary.
  90          */
  91         if (tvp) {
  92                 (void) gettimeofday(&starttv, NILTZ);
  93                 endtv = *tvp;
  94                 s = &endtv;
  95         } else
  96                 s = 0;
  97 again:
  98         set[0].fd = STDIN_FILENO;
  99         set[0].events = POLLIN;
 100         switch (poll(set, 1, s->tv_sec * 1000 + s->tv_usec / 1000)) {
 101
 102         case -1:
 103                 if (tvp == 0)
 104                         return (-1);
 105                 if (errno == EINTR)
 106                         goto again;
 107                 stop("select failed, help");
 108                 /* NOTREACHED */
 109
 110         case 0: /* timed out */
 111                 tvp->tv_sec = 0;
 112                 tvp->tv_usec = 0;
 113                 return (0);
 114         }
 115         if (tvp) {
 116                 /* since there is input, we may not have timed out */
 117                 (void) gettimeofday(&endtv, NILTZ);
 118                 TV_SUB(&endtv, &starttv);
 119                 TV_SUB(tvp, &endtv);    /* adjust *tvp by elapsed time */
 120         }
 121         return (1);
 122 }
 123
 124 /*
 125  * `sleep' for the current turn time (using select).
 126  * Eat any input that might be available.
 127  */
 128 void
 129 tsleep()
 130 {
 131         struct timeval tv;
 132         char c;
 133
 134         tv.tv_sec = 0;
 135         tv.tv_usec = fallrate;
 136         while (TV_POS(&tv))
 137                 if (rwait(&tv) && read(0, &c, 1) != 1)
 138                         break;
 139 }
 140
 141 /*
 142  * getchar with timeout.
 143  */
 144 int
 145 tgetchar()
 146 {
 147         static struct timeval timeleft;
 148         char c;
 149
 150         /*
 151          * Reset timeleft to fallrate whenever it is not positive.
 152          * In any case, wait to see if there is any input.  If so,
 153          * take it, and update timeleft so that the next call to
 154          * tgetchar() will not wait as long.  If there is no input,
 155          * make timeleft zero or negative, and return -1.
 156          *
 157          * Most of the hard work is done by rwait().
 158          */
 159         if (!TV_POS(&timeleft)) {
 160                 faster();       /* go faster */
 161                 timeleft.tv_sec = 0;
 162                 timeleft.tv_usec = fallrate;
 163         }
 164         if (!rwait(&timeleft))
 165                 return (-1);
 166         if (read(0, &c, 1) != 1)
 167                 stop("end of file, help");
 168         return ((int)(unsigned char)c);
 169 }