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1419 jermar 1
/*  $OpenBSD: input.c,v 1.12 2005/04/13 02:33:08 deraadt Exp $  */
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/*    $NetBSD: input.c,v 1.3 1996/02/06 22:47:33 jtc Exp $    */
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/*-
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 * Copyright (c) 1992, 1993
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 *  The Regents of the University of California.  All rights reserved.
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 *
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 * This code is derived from software contributed to Berkeley by
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 * Chris Torek and Darren F. Provine.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 * 1. Redistributions of source code must retain the above copyright
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 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    notice, this list of conditions and the following disclaimer in the
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 *    documentation and/or other materials provided with the distribution.
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 * 3. Neither the name of the University nor the names of its contributors
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 *    may be used to endorse or promote products derived from this software
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 *    without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 * SUCH DAMAGE.
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 *
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 *  @(#)input.c 8.1 (Berkeley) 5/31/93
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 */
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/*
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 * Tetris input.
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 */
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#include <sys/types.h>
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#include <sys/time.h>
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#include <errno.h>
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#include <unistd.h>
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#include <string.h>
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#include "input.h"
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#include "tetris.h"
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/* return true iff the given timeval is positive */
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#define TV_POS(tv) \
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    ((tv)->tv_sec > 0 || ((tv)->tv_sec == 0 && (tv)->tv_usec > 0))
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/* subtract timeval `sub' from `res' */
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#define TV_SUB(res, sub) \
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    (res)->tv_sec -= (sub)->tv_sec; \
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    (res)->tv_usec -= (sub)->tv_usec; \
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    if ((res)->tv_usec < 0) { \
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        (res)->tv_usec += 1000000; \
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        (res)->tv_sec--; \
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    }
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/*
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 * Do a `read wait': select for reading from stdin, with timeout *tvp.
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 * On return, modify *tvp to reflect the amount of time spent waiting.
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 * It will be positive only if input appeared before the time ran out;
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 * otherwise it will be zero or perhaps negative.
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 *
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 * If tvp is nil, wait forever, but return if select is interrupted.
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 *
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 * Return 0 => no input, 1 => can read() from stdin
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 */
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int
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rwait(struct timeval *tvp)
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{
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    struct timeval starttv, endtv, *s;
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    fd_set fds;
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#define NILTZ ((struct timezone *)0)
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    /*
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     * Someday, select() will do this for us.
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     * Just in case that day is now, and no one has
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     * changed this, we use a temporary.
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     */
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    if (tvp) {
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        (void) gettimeofday(&starttv, NILTZ);
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        endtv = *tvp;
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        s = &endtv;
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    } else
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        s = NULL;
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again:
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    FD_ZERO(&fds);
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    FD_SET(STDIN_FILENO, &fds);
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    switch (select(STDIN_FILENO + 1, &fds, (fd_set *)0, (fd_set *)0, s)) {
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    case -1:
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        if (tvp == 0)
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            return (-1);
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        if (errno == EINTR)
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            goto again;
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        stop("select failed, help");
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        /* NOTREACHED */
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    case 0: /* timed out */
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        tvp->tv_sec = 0;
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        tvp->tv_usec = 0;
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        return (0);
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    }
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    if (tvp) {
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        /* since there is input, we may not have timed out */
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        (void) gettimeofday(&endtv, NILTZ);
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        TV_SUB(&endtv, &starttv);
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        TV_SUB(tvp, &endtv);    /* adjust *tvp by elapsed time */
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    }
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    return (1);
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}
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/*
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 * `sleep' for the current turn time (using select).
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 * Eat any input that might be available.
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 */
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void
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tsleep(void)
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{
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    struct timeval tv;
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    char c;
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    tv.tv_sec = 0;
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    tv.tv_usec = fallrate;
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    while (TV_POS(&tv))
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        if (rwait(&tv) && read(STDIN_FILENO, &c, 1) != 1)
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            break;
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}
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/*
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 * getchar with timeout.
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 */
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int
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tgetchar(void)
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{
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    static struct timeval timeleft;
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    char c;
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    /*
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     * Reset timeleft to fallrate whenever it is not positive.
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     * In any case, wait to see if there is any input.  If so,
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     * take it, and update timeleft so that the next call to
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     * tgetchar() will not wait as long.  If there is no input,
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     * make timeleft zero or negative, and return -1.
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     *
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     * Most of the hard work is done by rwait().
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     */
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    if (!TV_POS(&timeleft)) {
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        faster();   /* go faster */
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        timeleft.tv_sec = 0;
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        timeleft.tv_usec = fallrate;
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    }
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    if (!rwait(&timeleft))
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        return (-1);
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    if (read(STDIN_FILENO, &c, 1) != 1)
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        stop("end of file, help");
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    return ((int)(unsigned char)c);
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}