1 /****************************************************************************
2  * Copyright (c) 1998-2011,2012 Free Software Foundation, Inc.              *
3  *                                                                          *
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22  *                                                                          *
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28 
29 /****************************************************************************
30  *  Author: Zeyd M. Ben-Halim <zmbenhal@netcom.com> 1992,1995               *
31  *     and: Eric S. Raymond <esr@snark.thyrsus.com>                         *
32  *     and: Thomas E. Dickey                        1996-on                 *
33  *     and: Juergen Pfeifer                         2009                    *
34  ****************************************************************************/
35 
36 /*
37 **	lib_ungetch.c
38 **
39 **	The routine ungetch().
40 **
41 */
42 
43 #include <curses.priv.h>
44 
45 MODULE_ID("$Id: lib_ungetch.c,v 1.16 2012/08/04 17:38:53 tom Exp $")
46 
47 #include <fifo_defs.h>
48 
49 #ifdef TRACE
50 NCURSES_EXPORT(void)
51 _nc_fifo_dump(SCREEN *sp)
52 {
53     int i;
54     T(("head = %d, tail = %d, peek = %d", head, tail, peek));
55     for (i = 0; i < 10; i++)
56 	T(("char %d = %s", i, _nc_tracechar(sp, sp->_fifo[i])));
57 }
58 #endif /* TRACE */
59 
60 NCURSES_EXPORT(int)
61 safe_ungetch(SCREEN *sp, int ch)
62 {
63     int rc = ERR;
64 
65     T((T_CALLED("ungetch(%p,%s)"), (void *) sp, _nc_tracechar(sp, ch)));
66 
67     if (sp != 0 && tail >= 0) {
68 	if (head < 0) {
69 	    head = 0;
70 	    t_inc();
71 	    peek = tail;	/* no raw keys */
72 	} else {
73 	    h_dec();
74 	}
75 
76 	sp->_fifo[head] = ch;
77 	T(("ungetch %s ok", _nc_tracechar(sp, ch)));
78 #ifdef TRACE
79 	if (USE_TRACEF(TRACE_IEVENT)) {
80 	    _nc_fifo_dump(sp);
81 	    _nc_unlock_global(tracef);
82 	}
83 #endif
84 	rc = OK;
85     }
86     returnCode(rc);
87 }
88 
89 NCURSES_EXPORT(int)
90 ungetch(int ch)
91 {
92     return safe_ungetch(CURRENT_SCREEN, ch);
93 }
94