games/tetris/input.c

   1 /*      $NetBSD: input.c,v 1.10 2006/03/19 00:50:28 christos 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(struct timeval *tvp)
  76 {
  77         struct pollfd set[1];
  78         struct timeval starttv, endtv;
  79         int timeout;
  80 #define NILTZ ((struct timezone *)0)
  81
  82         if (tvp) {
  83                 (void) gettimeofday(&starttv, NILTZ);
  84                 endtv = *tvp;
  85                 timeout = tvp->tv_sec * 1000 + tvp->tv_usec / 1000;
  86         } else
  87                 timeout = INFTIM;
  88 again:
  89         set[0].fd = STDIN_FILENO;
  90         set[0].events = POLLIN;
  91         switch (poll(set, 1, timeout)) {
  92
  93         case -1:
  94                 if (tvp == 0)
  95                         return (-1);
  96                 if (errno == EINTR)
  97                         goto again;
  98                 stop("poll failed, help");
  99                 /* NOTREACHED */
 100
 101         case 0: /* timed out */
 102                 if (tvp) {
 103                         tvp->tv_sec = 0;
 104                         tvp->tv_usec = 0;
 105                 }
 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.
 119  * Eat any input that might be available.
 120  */
 121 void
 122 tsleep(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(0, &c, 1) != 1)
 131                         break;
 132 }
 133
 134 /*
 135  * getchar with timeout.
 136  */
 137 int
 138 tgetchar(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(0, &c, 1) != 1)
 160                 stop("end of file, help");
 161         return ((int)(unsigned char)c);
 162 }