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tetex-bin  3.0
lib_ungetch.c
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00001 /****************************************************************************
00002  * Copyright (c) 1998-2001,2002 Free Software Foundation, Inc.              *
00003  *                                                                          *
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00005  * copy of this software and associated documentation files (the            *
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00010  * furnished to do so, subject to the following conditions:                 *
00011  *                                                                          *
00012  * The above copyright notice and this permission notice shall be included  *
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00014  *                                                                          *
00015  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS  *
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00022  *                                                                          *
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00028 
00029 /****************************************************************************
00030  *  Author: Zeyd M. Ben-Halim <zmbenhal@netcom.com> 1992,1995               *
00031  *     and: Eric S. Raymond <esr@snark.thyrsus.com>                         *
00032  ****************************************************************************/
00033 
00034 /*
00035 **     lib_ungetch.c
00036 **
00037 **     The routine ungetch().
00038 **
00039 */
00040 
00041 #include <curses.priv.h>
00042 
00043 MODULE_ID("$Id: lib_ungetch.c,v 1.8 2002/08/24 22:08:48 tom Exp $")
00044 
00045 #include <fifo_defs.h>
00046 
00047 #ifdef TRACE
00048 NCURSES_EXPORT(void)
00049 _nc_fifo_dump(void)
00050 {
00051     int i;
00052     T(("head = %d, tail = %d, peek = %d", head, tail, peek));
00053     for (i = 0; i < 10; i++)
00054        T(("char %d = %s", i, _tracechar(SP->_fifo[i])));
00055 }
00056 #endif /* TRACE */
00057 
00058 NCURSES_EXPORT(int)
00059 ungetch(int ch)
00060 {
00061     T((T_CALLED("ungetch(%s)"), _tracechar(ch)));
00062 
00063     if (tail == -1)
00064        returnCode(ERR);
00065     if (head == -1) {
00066        head = 0;
00067        t_inc()
00068            peek = tail;     /* no raw keys */
00069     } else
00070        h_dec();
00071 
00072     SP->_fifo[head] = ch;
00073     T(("ungetch %s ok", _tracechar(ch)));
00074 #ifdef TRACE
00075     if (_nc_tracing & TRACE_IEVENT)
00076        _nc_fifo_dump();
00077 #endif
00078     returnCode(OK);
00079 }