1/****************************************************************************
2 * Copyright 2020 Thomas E. Dickey                                          *
3 * Copyright 1998-2011,2012 Free Software Foundation, Inc.                  *
4 *                                                                          *
5 * Permission is hereby granted, free of charge, to any person obtaining a  *
6 * copy of this software and associated documentation files (the            *
7 * "Software"), to deal in the Software without restriction, including      *
8 * without limitation the rights to use, copy, modify, merge, publish,      *
9 * distribute, distribute with modifications, sublicense, and/or sell       *
10 * copies of the Software, and to permit persons to whom the Software is    *
11 * furnished to do so, subject to the following conditions:                 *
12 *                                                                          *
13 * The above copyright notice and this permission notice shall be included  *
14 * in all copies or substantial portions of the Software.                   *
15 *                                                                          *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS  *
17 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF               *
18 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.   *
19 * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,   *
20 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR    *
21 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR    *
22 * THE USE OR OTHER DEALINGS IN THE SOFTWARE.                               *
23 *                                                                          *
24 * Except as contained in this notice, the name(s) of the above copyright   *
25 * holders shall not be used in advertising or otherwise to promote the     *
26 * sale, use or other dealings in this Software without prior written       *
27 * authorization.                                                           *
28 ****************************************************************************/
29
30/****************************************************************************
31 *  Author: Zeyd M. Ben-Halim <zmbenhal@netcom.com> 1992,1995               *
32 *     and: Eric S. Raymond <esr@snark.thyrsus.com>                         *
33 *     and: Thomas E. Dickey                        1996-on                 *
34 *     and: Juergen Pfeifer                         2009                    *
35 ****************************************************************************/
36
37/*
38**	lib_ungetch.c
39**
40**	The routine ungetch().
41**
42*/
43
44#include <curses.priv.h>
45
46MODULE_ID("$Id: lib_ungetch.c,v 1.17 2020/02/02 23:34:34 tom Exp $")
47
48#include <fifo_defs.h>
49
50#ifdef TRACE
51NCURSES_EXPORT(void)
52_nc_fifo_dump(SCREEN *sp)
53{
54    int i;
55    T(("head = %d, tail = %d, peek = %d", head, tail, peek));
56    for (i = 0; i < 10; i++)
57	T(("char %d = %s", i, _nc_tracechar(sp, sp->_fifo[i])));
58}
59#endif /* TRACE */
60
61NCURSES_EXPORT(int)
62safe_ungetch(SCREEN *sp, int ch)
63{
64    int rc = ERR;
65
66    T((T_CALLED("ungetch(%p,%s)"), (void *) sp, _nc_tracechar(sp, ch)));
67
68    if (sp != 0 && tail >= 0) {
69	if (head < 0) {
70	    head = 0;
71	    t_inc();
72	    peek = tail;	/* no raw keys */
73	} else {
74	    h_dec();
75	}
76
77	sp->_fifo[head] = ch;
78	T(("ungetch %s ok", _nc_tracechar(sp, ch)));
79#ifdef TRACE
80	if (USE_TRACEF(TRACE_IEVENT)) {
81	    _nc_fifo_dump(sp);
82	    _nc_unlock_global(tracef);
83	}
84#endif
85	rc = OK;
86    }
87    returnCode(rc);
88}
89
90NCURSES_EXPORT(int)
91ungetch(int ch)
92{
93    return safe_ungetch(CURRENT_SCREEN, ch);
94}
95