usr/src/lib/libcurses/screen/ungetch.c

   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 #pragma ident   "%Z%%M% %I%     %E% SMI"
  41
  42 /*LINTLIBRARY*/
  43
  44 #include <sys/types.h>
  45 #include "curses_inc.h"
  46
  47 /* Place a char onto the beginning of the input queue. */
  48
  49 int
  50 ungetch(int ch)
  51 {
  52         int     i = cur_term->_chars_on_queue, j = i - 1;
  53         chtype  *inputQ = cur_term->_input_queue;
  54
  55         /* Place the character at the beg of the Q */
  56         /*
  57          * Here is commented out because 'ch' should deal with a single byte
  58          * character only. So ISCBIT(ch) is 0 every time.
  59          *
  60          * register chtype      r;
  61          *
  62          * if (ISCBIT(ch)) {
  63          *      r = RBYTE(ch);
  64          *      ch = LBYTE(ch);
  65          *      -* do the right half first to maintain the byte order *-
  66          *      if (r != MBIT && ungetch(r) == ERR)
  67          *              return (ERR);
  68          * }
  69          */
  70
  71         while (i > 0)
  72                 inputQ[i--] = inputQ[j--];
  73         cur_term->_ungotten++;
  74         inputQ[0] = -ch;
  75         cur_term->_chars_on_queue++;
  76         return (0);
  77 }