tetris/input.c

   1 /*      $NetBSD: input.c,v 1.3 1996/02/06 22:47:33 jtc 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
  48 #include <errno.h>
  49 #include <unistd.h>
  50
  51 #include "input.h"
  52 #include "tetris.h"
  53
  54 /* return true iff the given timeval is positive */
  55 #define TV_POS(tv) \
  56         ((tv)->tv_sec > 0 || ((tv)->tv_sec == 0 && (tv)->tv_usec > 0))
  57
  58 /* subtract timeval `sub' from `res' */
  59 #define TV_SUB(res, sub) \
  60         (res)->tv_sec -= (sub)->tv_sec; \
  61         (res)->tv_usec -= (sub)->tv_usec; \
  62         if ((res)->tv_usec < 0) { \
  63                 (res)->tv_usec += 1000000; \
  64                 (res)->tv_sec--; \
  65         }
  66
  67 /*
  68  * Do a `read wait': select for reading from stdin, with timeout *tvp.
  69  * On return, modify *tvp to reflect the amount of time spent waiting.
  70  * It will be positive only if input appeared before the time ran out;
  71  * otherwise it will be zero or perhaps negative.
  72  *
  73  * If tvp is nil, wait forever, but return if select is interrupted.
  74  *
  75  * Return 0 => no input, 1 => can read() from stdin
  76  */
  77 int
  78 rwait(tvp)
  79         register struct timeval *tvp;
  80 {
  81         int i;
  82         struct timeval starttv, endtv, *s;
  83 #define NILTZ ((struct timezone *)0)
  84
  85         /*
  86          * Someday, select() will do this for us.
  87          * Just in case that day is now, and no one has
  88          * changed this, we use a temporary.
  89          */
  90         if (tvp) {
  91                 (void) gettimeofday(&starttv, NILTZ);
  92                 endtv = *tvp;
  93                 s = &endtv;
  94         } else
  95                 s = 0;
  96 again:
  97         i = 1;
  98         switch (select(1, (fd_set *)&i, (fd_set *)0, (fd_set *)0, s)) {
  99
 100         case -1:
 101                 if (tvp == 0)
 102                         return (-1);
 103                 if (errno == EINTR)
 104                         goto again;
 105                 stop("select failed, help");
 106                 /* NOTREACHED */
 107
 108         case 0: /* timed out */
 109                 tvp->tv_sec = 0;
 110                 tvp->tv_usec = 0;
 111                 return (0);
 112         }
 113         if (tvp) {
 114                 /* since there is input, we may not have timed out */
 115                 (void) gettimeofday(&endtv, NILTZ);
 116                 TV_SUB(&endtv, &starttv);
 117                 TV_SUB(tvp, &endtv);    /* adjust *tvp by elapsed time */
 118         }
 119         return (1);
 120 }
 121
 122 /*
 123  * `sleep' for the current turn time (using select).
 124  * Eat any input that might be available.
 125  */
 126 void
 127 tsleep()
 128 {
 129         struct timeval tv;
 130         char c;
 131
 132         tv.tv_sec = 0;
 133         tv.tv_usec = fallrate;
 134         while (TV_POS(&tv))
 135                 if (rwait(&tv) && read(0, &c, 1) != 1)
 136                         break;
 137 }
 138
 139 /*
 140  * Eat up any input (used at end of game).
 141  */
 142 void
 143 eat_input()
 144 {
 145         struct timeval tv;
 146         char c;
 147
 148         do {
 149                 tv.tv_sec = tv.tv_usec = 0;
 150         } while (rwait(&tv) && read(0, &c, 1) == 1);
 151 }
 152
 153 /*
 154  * getchar with timeout.
 155  */
 156 int
 157 tgetchar()
 158 {
 159         static struct timeval timeleft;
 160         char c;
 161
 162         /*
 163          * Reset timeleft to fallrate whenever it is not positive.
 164          * In any case, wait to see if there is any input.  If so,
 165          * take it, and update timeleft so that the next call to
 166          * tgetchar() will not wait as long.  If there is no input,
 167          * make timeleft zero or negative, and return -1.
 168          *
 169          * Most of the hard work is done by rwait().
 170          */
 171         if (!TV_POS(&timeleft)) {
 172                 faster();       /* go faster */
 173                 timeleft.tv_sec = 0;
 174                 timeleft.tv_usec = fallrate;
 175         }
 176         if (!rwait(&timeleft))
 177                 return (-1);
 178         if (read(0, &c, 1) != 1)
 179                 stop("end of file, help");
 180         return ((int)(unsigned char)c);
 181 }