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