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/* $OpenBSD: input.c,v 1.19 2017/08/13 02:12:16 tedu Exp $ */
/* $NetBSD: input.c,v 1.3 1996/02/06 22:47:33 jtc Exp $ */
/*-
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Chris Torek and Darren F. Provine.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)input.c 8.1 (Berkeley) 5/31/93
*/
/*
* Tetris input.
*/
#include <sys/time.h>
#include <errno.h>
#include <poll.h>
#include <time.h>
#include <unistd.h>
#include "input.h"
#include "tetris.h"
/* return true iff the given timespec is positive */
#define TS_POS(ts) \
((ts)->tv_sec > 0 || ((ts)->tv_sec == 0 && (ts)->tv_nsec > 0))
/*
* Do a `read wait': poll for reading from stdin, with timeout *limit.
* On return, subtract the time spent waiting from *limit.
* It will be positive only if input appeared before the time ran out;
* otherwise it will be zero or perhaps negative.
*
* If limit is NULL, wait forever, but return if poll is interrupted.
*
* Return 0 => no input, 1 => can read() from stdin, -1 => interrupted
*/
int
rwait(struct timespec *limit)
{
struct timespec start, end, elapsed;
struct pollfd pfd[1];
pfd[0].fd = STDIN_FILENO;
pfd[0].events = POLLIN;
if (limit != NULL)
clock_gettime(CLOCK_MONOTONIC, &start);
again:
switch (ppoll(pfd, 1, limit, NULL)) {
case -1:
if (limit == NULL)
return (-1);
if (errno == EINTR)
goto again;
stop("poll failed, help");
case 0: /* timed out */
timespecclear(limit);
return (0);
}
if (limit != NULL) {
/* we have input, so subtract the elapsed time from *limit */
clock_gettime(CLOCK_MONOTONIC, &end);
timespecsub(&end, &start, &elapsed);
timespecsub(limit, &elapsed, limit);
}
return (1);
}
/*
* `sleep' for the current turn time and eat any
* input that becomes available.
*/
void
tsleep(void)
{
struct timespec ts;
char c;
ts.tv_sec = 0;
ts.tv_nsec = fallrate;
while (TS_POS(&ts))
if (rwait(&ts) && read(STDIN_FILENO, &c, 1) != 1)
break;
}
/*
* getchar with timeout.
*/
int
tgetchar(void)
{
static struct timespec timeleft;
char c;
/*
* Reset timeleft to fallrate whenever it is not positive.
* In any case, wait to see if there is any input. If so,
* take it, and update timeleft so that the next call to
* tgetchar() will not wait as long. If there is no input,
* make timeleft zero or negative, and return -1.
*
* Most of the hard work is done by rwait().
*/
if (!TS_POS(&timeleft)) {
faster(); /* go faster */
timeleft.tv_sec = 0;
timeleft.tv_nsec = fallrate;
}
if (!rwait(&timeleft))
return (-1);
if (read(STDIN_FILENO, &c, 1) != 1)
stop("end of file, help");
return ((int)(unsigned char)c);
}
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