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  1. /*  $OpenBSD: input.c,v 1.12 2005/04/13 02:33:08 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 <string.h>
  48.  
  49. #include "input.h"
  50. #include "tetris.h"
  51.  
  52. #include <async.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. static aid_t getchar_inprog = 0;
  68.  
  69. /*
  70.  * Do a `read wait': select for reading from stdin, with timeout *tvp.
  71.  * On return, modify *tvp to reflect the amount of time spent waiting.
  72.  * It will be positive only if input appeared before the time ran out;
  73.  * otherwise it will be zero or perhaps negative.
  74.  *
  75.  * If tvp is nil, wait forever, but return if select is interrupted.
  76.  *
  77.  * Return 0 => no input, 1 => can read() from stdin
  78.  */
  79. int
  80. rwait(struct timeval *tvp)
  81. {
  82.     struct timeval starttv, endtv, *s;
  83.     fd_set fds;
  84.  
  85. #define NILTZ ((struct timezone *)0)
  86.  
  87.     /*
  88.      * Someday, select() will do this for us.
  89.      * Just in case that day is now, and no one has
  90.      * changed this, we use a temporary.
  91.      */
  92.     if (tvp) {
  93.         (void) gettimeofday(&starttv, NILTZ);
  94.         endtv = *tvp;
  95.         s = &endtv;
  96.     } else
  97.         s = NULL;
  98. again:
  99.     FD_ZERO(&fds);
  100.     FD_SET(STDIN_FILENO, &fds);
  101.     switch (select(STDIN_FILENO + 1, &fds, (fd_set *)0, (fd_set *)0, s)) {
  102.  
  103.     case -1:
  104.         if (tvp == 0)
  105.             return (-1);
  106.         if (errno == EINTR)
  107.             goto again;
  108.         stop("select failed, help");
  109.         /* NOTREACHED */
  110.  
  111.     case 0: /* timed out */
  112.         tvp->tv_sec = 0;
  113.         tvp->tv_usec = 0;
  114.         return (0);
  115.     }
  116.     if (tvp) {
  117.         /* since there is input, we may not have timed out */
  118.         (void) gettimeofday(&endtv, NILTZ);
  119.         TV_SUB(&endtv, &starttv);
  120.         TV_SUB(tvp, &endtv);    /* adjust *tvp by elapsed time */
  121.     }
  122.     return (1);
  123. }
  124.  
  125. /*
  126.  * `sleep' for the current turn time (using select).
  127.  * Eat any input that might be available.
  128.  */
  129. void
  130. tsleep(void)
  131. {
  132.     struct timeval tv;
  133.     char c;
  134.  
  135.     tv.tv_sec = 0;
  136.     tv.tv_usec = fallrate;
  137.     while (TV_POS(&tv))
  138.         if (rwait(&tv) && read(STDIN_FILENO, &c, 1) != 1)
  139.             break;
  140. }
  141.  
  142. /*
  143.  * getchar with timeout.
  144.  */
  145. int
  146. tgetchar(void)
  147. {
  148.     static struct timeval timeleft;
  149.     char c;
  150.  
  151.     /*
  152.      * Reset timeleft to fallrate whenever it is not positive.
  153.      * In any case, wait to see if there is any input.  If so,
  154.      * take it, and update timeleft so that the next call to
  155.      * tgetchar() will not wait as long.  If there is no input,
  156.      * make timeleft zero or negative, and return -1.
  157.      *
  158.      * Most of the hard work is done by rwait().
  159.      */
  160.     if (!TV_POS(&timeleft)) {
  161.         faster();   /* go faster */
  162.         timeleft.tv_sec = 0;
  163.         timeleft.tv_usec = fallrate;
  164.     }
  165.     if (!rwait(&timeleft))
  166.         return (-1);
  167.     if (read(STDIN_FILENO, &c, 1) != 1)
  168.         stop("end of file, help");
  169.     return ((int)(unsigned char)c);
  170. }
  171.