tetris/input.c

   1 /*      $NetBSD: input.c,v 1.9 2003/08/07 09:37:47 agc 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(tvp)
  76         struct timeval *tvp;
  77 {
  78         struct pollfd set[1];
  79         struct timeval starttv, endtv;
  80         int timeout;
  81 #define NILTZ ((struct timezone *)0)
  82
  83         if (tvp) {
  84                 (void) gettimeofday(&starttv, NILTZ);
  85                 endtv = *tvp;
  86                 timeout = tvp->tv_sec * 1000 + tvp->tv_usec / 1000;
  87         } else
  88                 timeout = INFTIM;
  89 again:
  90         set[0].fd = STDIN_FILENO;
  91         set[0].events = POLLIN;
  92         switch (poll(set, 1, timeout)) {
  93
  94         case -1:
  95                 if (tvp == 0)
  96                         return (-1);
  97                 if (errno == EINTR)
  98                         goto again;
  99                 stop("poll failed, help");
 100                 /* NOTREACHED */
 101
 102         case 0: /* timed out */
 103                 tvp->tv_sec = 0;
 104                 tvp->tv_usec = 0;
 105                 return (0);
 106         }
 107         if (tvp) {
 108                 /* since there is input, we may not have timed out */
 109                 (void) gettimeofday(&endtv, NILTZ);
 110                 TV_SUB(&endtv, &starttv);
 111                 TV_SUB(tvp, &endtv);    /* adjust *tvp by elapsed time */
 112         }
 113         return (1);
 114 }
 115
 116 /*
 117  * `sleep' for the current turn time.
 118  * Eat any input that might be available.
 119  */
 120 void
 121 tsleep()
 122 {
 123         struct timeval tv;
 124         char c;
 125
 126         tv.tv_sec = 0;
 127         tv.tv_usec = fallrate;
 128         while (TV_POS(&tv))
 129                 if (rwait(&tv) && read(0, &c, 1) != 1)
 130                         break;
 131 }
 132
 133 /*
 134  * getchar with timeout.
 135  */
 136 int
 137 tgetchar()
 138 {
 139         static struct timeval timeleft;
 140         char c;
 141
 142         /*
 143          * Reset timeleft to fallrate whenever it is not positive.
 144          * In any case, wait to see if there is any input.  If so,
 145          * take it, and update timeleft so that the next call to
 146          * tgetchar() will not wait as long.  If there is no input,
 147          * make timeleft zero or negative, and return -1.
 148          *
 149          * Most of the hard work is done by rwait().
 150          */
 151         if (!TV_POS(&timeleft)) {
 152                 faster();       /* go faster */
 153                 timeleft.tv_sec = 0;
 154                 timeleft.tv_usec = fallrate;
 155         }
 156         if (!rwait(&timeleft))
 157                 return (-1);
 158         if (read(0, &c, 1) != 1)
 159                 stop("end of file, help");
 160         return ((int)(unsigned char)c);
 161 }