/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 1997 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*      Copyright (c) 1988 AT&T */
/*        All Rights Reserved   */

/*
 * University Copyright- Copyright (c) 1982, 1986, 1988
 * The Regents of the University of California
 * All Rights Reserved
 *
 * University Acknowledgment- Portions of this document are derived from
 * software developed by the University of California, Berkeley, and its
 * contributors.
 */

/*LINTLIBRARY*/

/*
 * chkinput()
 *
 * Routine to check to see if any input is waiting.
 * It returns a 1 if there is input waiting, and a zero if
 * no input is waiting.
 *
 * This function replaces system calls to ioctl() with the FIONREAD
 * parameter. It enables curses to stop a screen refresh whenever
 * a character is input.
 * Standard BTL UNIX 4.0 or 5.0 does not handle FIONREAD.
 * Changes have been made to 'wrefresh.c' to
 * call this routine as "_inputpending = chkinput()".
 * (delay.c and getch.c also use FIONREAD for nodelay, select and fast peek,
 * but these routines have not been changed).
 *
 * Philip N. Crusius - July 20, 1983
 * Modified to handle various systems March 9, 1984 by Mark Horton.
 */

#include        <unistd.h>
#include        <sys/types.h>
#include        "curses_inc.h"

#ifdef  FIONREAD
#define HAVE_CHK

int
_chkinput(void)
{
        int     i;

        ioctl(SP->check_fd, FIONREAD, &i);
        return (i > 0);
}
#endif  /* FIONREAD */

#ifdef  SELECT
#ifndef HAVE_CHK
#define HAVE_CHK

int
_chkinput(void)
{
        int ifds, ofds, efds, n;
        struct timeval tv;

        ifds = 1 << SP->check_fd;
        ofds = efds = 0;
        tv.tv_sec = tv.t_usec = 0;
        n = select(20, &ifds, &ofds, &efds, &tv);
        return (n > 0);
}
#endif  /* HAVE_CHK */
#endif  /* SELECT */

#ifndef HAVE_CHK
#ifdef  SYSV

int
_chkinput(void)
{
        unsigned        char    c;      /* character input */

        /*
         * Only check typeahead if the user is using our input
         * routines. This is because the read below will put
         * stuff into the inputQ that will never be read and the
         * screen will never get updated from now on.
         * This code should GO AWAY when a poll() or FIONREAD can
         * be done on the file descriptor as then the check
         * will be non-destructive.
         */

        if (!cur_term->fl_typeahdok ||
            (cur_term->_chars_on_queue == INP_QSIZE) ||
            (cur_term->_check_fd < 0)) {
                goto bad;
        }

        /* If input is waiting in curses queue, return (TRUE). */

        if ((int)cur_term->_chars_on_queue > 0) {
#ifdef  DEBUG
                if (outf) {
                        (void) fprintf(outf, "Found a character on the input "
                            "queue\n");
                        _print_queue();
                }
#endif  /* DEBUG */
                goto good;
        }

        if (read(cur_term->_check_fd, (char *)&c, 1) > 0) {
#ifdef  DEBUG
                if (outf) {
                        (void) fprintf(outf, "Reading ahead\n");
                }
#endif  /* DEBUG */
                /*
                 * A character was waiting.  Put it at the end
                 * of the curses queue and return 1 to show that
                 * input is waiting.
                 */
#ifdef  DEBUG
                if (outf)
                        _print_queue();
#endif  /* DEBUG */
                cur_term->_input_queue[cur_term->_chars_on_queue++] = c;
good:
                return (TRUE);
        } else {
                /* No input was waiting so return 0. */
#ifdef  DEBUG
                if (outf)
                        (void) fprintf(outf, "No input waiting\n");
#endif  /* DEBUG */
bad:
                return (FALSE);
        }
}
#else   /* SYSV */
int
_chkinput()
{
        return (FALSE);
}
#endif  /* SYSV */
#endif  /* HAVE_CHK */

#ifdef  DEBUG
void
_print_queue()  /* FOR DEBUG ONLY */
{
        int             i, j = cur_term->_chars_on_queue;
        chtype          *inputQ = cur_term->_input_queue;

        if (outf)
                for (i = 0; i < j; i++)
                        (void) fprintf(outf, "inputQ[%d] = %c\n", i, inputQ[i]);
}
#endif  /* DEBUG */