xref: /illumos-gate/usr/src/lib/libcurses/screen/ungetch.c (revision 1a2d662a91cee3bf82f41cd47c7ae6f3825d9db2)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 /*
23  * Copyright 1997 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 /*	Copyright (c) 1988 AT&T	*/
28 /*	  All Rights Reserved	*/
29 
30 /*
31  * University Copyright- Copyright (c) 1982, 1986, 1988
32  * The Regents of the University of California
33  * All Rights Reserved
34  *
35  * University Acknowledgment- Portions of this document are derived from
36  * software developed by the University of California, Berkeley, and its
37  * contributors.
38  */
39 
40 /*LINTLIBRARY*/
41 
42 #include <sys/types.h>
43 #include "curses_inc.h"
44 
45 /* Place a char onto the beginning of the input queue. */
46 
47 int
48 ungetch(int ch)
49 {
50 	int	i = cur_term->_chars_on_queue, j = i - 1;
51 	chtype	*inputQ = cur_term->_input_queue;
52 
53 	/* Place the character at the beg of the Q */
54 	/*
55 	 * Here is commented out because 'ch' should deal with a single byte
56 	 * character only. So ISCBIT(ch) is 0 every time.
57 	 *
58 	 * register chtype	r;
59 	 *
60 	 * if (ISCBIT(ch)) {
61 	 *	r = RBYTE(ch);
62 	 *	ch = LBYTE(ch);
63 	 *	-* do the right half first to maintain the byte order *-
64 	 *	if (r != MBIT && ungetch(r) == ERR)
65 	 *		return (ERR);
66 	 * }
67 	 */
68 
69 	while (i > 0)
70 		inputQ[i--] = inputQ[j--];
71 	cur_term->_ungotten++;
72 	inputQ[0] = -ch;
73 	cur_term->_chars_on_queue++;
74 	return (0);
75 }
76