lib_ungetch.c

ncurses-5.4

/****************************************************************************
 * Copyright (c) 1998-2001,2002 Free Software Foundation, Inc.              *
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/****************************************************************************
 *  Author: Zeyd M. Ben-Halim <[e-mail]> 1992,1995               *
 *     and: Eric S. Raymond <[e-mail]>                         *
 ****************************************************************************/

/*
**	lib_ungetch.c
**
**	The routine ungetch().
**
*/

#include <curses.priv.h>

MODULE_ID("$Id: lib_ungetch.c,v 1.8 2002/08/24 22:08:48 tom Exp $")

#include <fifo_defs.h>

#ifdef TRACE
NCURSES_EXPORT(void)
_nc_fifo_dump(void)
{
    int i;
    T(("head = %d, tail = %d, peek = %d", head, tail, peek));
    for (i = 0; i < 10; i++)
	T(("char %d = %s", i, _tracechar(SP->_fifo[i])));
}
#endif /* TRACE */

NCURSES_EXPORT(int)
ungetch(int ch)
{
    T((T_CALLED("ungetch(%s)"), _tracechar(ch)));

    if (tail == -1)
	returnCode(ERR);
    if (head == -1) {
	head = 0;
	t_inc()
	    peek = tail;	/* no raw keys */
    } else
	h_dec();

    SP->_fifo[head] = ch;
    T(("ungetch %s ok", _tracechar(ch)));
#ifdef TRACE
    if (_nc_tracing & TRACE_IEVENT)
	_nc_fifo_dump();
#endif
    returnCode(OK);
}