libcurses/screen/wrefresh.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*	Copyright (c) 1988 AT&T	*/
/*	  All Rights Reserved	*/

/*
 * University Copyright- Copyright (c) 1982, 1986, 1988
 * The Regents of the University of California
 * All Rights Reserved
 *
 * University Acknowledgment- Portions of this document are derived from
 * software developed by the University of California, Berkeley, and its
 * contributors.
 */

/*LINTLIBRARY*/

#include	<sys/types.h>
#include	<stdlib.h>
#include	<string.h>
#include	"curses_inc.h"

/*
 * Make the screen look like "win" over the area covered by win.
 * This routine may use insert/delete char/line and scrolling-region.
 * win : the window being updated
 */

extern int	outchcount;

static void	_updateln(int), _turn_off_background(void),
		_setmark1(int, int, chtype *),
		_setmark2(int, int, chtype *), _rmargin(int),
		_useceod(int, int);
static int	_useidch(chtype *, chtype *, int, int, int *),
		_prefix(chtype *, chtype *, int, int, int *),
		_getceod(int, int);

static	short	cy, cx,		/* current cursor coord */
		scrli,		/* actual screen lines */
		scrco;		/* actual screen columns */
static	char	**marks;	/* the mark table for cookie terminals */
static	char	**color_marks;	/* color mark table for cookie terminals */

#define	_ISMARK1(y, x)	(marks[y][x / BITSPERBYTE] & (1 << (x % BITSPERBYTE)))
#define	_ISMARK2(y, x)	(color_marks ? (color_marks[y][x / BITSPERBYTE] & \
			(1 << (x % BITSPERBYTE))) : FALSE)

#define	_VIDEO(c)	((c) & A_ATTRIBUTES & ~A_COLOR)
#define	_COLOR(c)	((c) & A_COLOR)

#ifdef	_VR2_COMPAT_CODE
extern	char	_endwin;
#endif	/* _VR2_COMPAT_CODE */

int
wrefresh(WINDOW *win)
{

	short	*bnsch, *ensch;
	SLK_MAP	*slk;
	int	wx, wy, nc, boty, clby, idby, *hs, curwin;

	curwin = (win == curscr);

	/* don't allow curscr refresh if the screen was just created */

	if (curwin && curscr->_sync)
		return (OK);

	/* go thru _stdbody */
	if (!curwin && (win != _virtscr))
		(void) wnoutrefresh(win);

	/* if there is typeahead */
	if ((_INPUTPENDING = _chkinput()) == TRUE) {
		if (curwin)
			curscr->_clear = TRUE;
		return (OK);
	}

	if (curwin || curscr->_clear)
		_virtscr->_clear = TRUE;

	/* save curscr cursor coordinates */
	cy = curscr->_cury;
	cx = curscr->_curx;

	/* to simplify code in some cases */
	marks = _MARKS;
	color_marks = _COLOR_MARKS;
	scrli = curscr->_maxy;
	scrco = curscr->_maxx;
	slk = SP->slk;

	outchcount = 0;

	/* make sure we're in program mode */
	if (SP->fl_endwin) {
		/* If endwin is equal to 2 it means we just did a newscreen. */
		if (SP->fl_endwin == TRUE) {
			(void) reset_prog_mode();
			if (SP->kp_state)
				(void) tputs(keypad_xmit, 1, _outch);
			if (slk)
				(*_do_slk_tch)();
			if (SP->fl_meta)
				(void) tputs(meta_on, 1, _outch);
			if (cur_term->_cursorstate != 1)
				_PUTS(cur_term->cursor_seq[cur_term->
				    _cursorstate], 0);
		}
		_PUTS(enter_ca_mode, 1);
		(void) tputs(ena_acs, 1, _outch);

		if (exit_attribute_mode)
			_PUTS(tparm_p0(exit_attribute_mode), 1);
		else
			/*
			 * If there is no exit_attribute mode, then vidupdate
			 * could only possibly turn off one of the below three
			 * so that's all we ask it turn off.
			 */
			vidupdate(A_NORMAL, (A_ALTCHARSET | A_STANDOUT |
			    A_UNDERLINE), _outch);

		SP->fl_endwin = FALSE;

#ifdef	_VR2_COMPAT_CODE
		_endwin = (char)FALSE;
#endif	/* _VR2_COMPAT_CODE */
	}

	/* clear the screen if required */
	if (_virtscr->_clear) {
/* SS: colors */
		if (back_color_erase)
			_turn_off_background();

		_PUTS(clear_screen, scrli);
		cy = cx = curscr->_curx = curscr->_cury = 0;

		/* _sync indicates that this a new screen */
		if (!curscr->_sync)
			(void) werase(curscr);
		else {
			nc = scrco / BITSPERBYTE - (scrco %
			    BITSPERBYTE ? 0 : 1);
			wy = scrli - 1;
			bnsch = _BEGNS; ensch = _ENDNS;
			hs = _CURHASH;
			for (; wy >= 0; --wy) {
				*bnsch++ = scrco;
				*ensch++ = -1;
				*hs++ = 0;
				if (marks)
					for (wx = nc; wx >= 0; --wx)
						marks[wy][wx] = 0;
			}
		}

		_virtscr->_clear = curscr->_sync = curscr->_clear = FALSE;
		if (slk)
			(*_do_slk_tch)();

		/* pretend _virtscr has been totally changed */
		(void) wtouchln(_virtscr, 0, scrli, -1);
		_VIRTTOP = 0;
		_VIRTBOT = scrli - 1;

		/* will not do clear-eod or ins/del lines */
		clby = idby = scrli;
	} else
		clby = idby = -1;

	/* Software soft labels; if _changed == 2, slk's are in clear mode. */
	if (slk && slk->_win && (slk->_changed == TRUE))
		(*_do_slk_noref)();

	/* do line updating */
	_virtscr->_clear = FALSE;
	wy = _VIRTTOP;
	boty = _VIRTBOT + 1;
	bnsch = _virtscr->_firstch + wy;
	ensch = _virtscr->_lastch + wy;

	for (; wy < boty; ++wy, ++bnsch, ++ensch) {
		/* this line is up-to-date */
		if (*bnsch >= scrco)
			goto next;

		/* there is type-ahead */
		if (!curwin && (_INPUTPENDING = _chkinput()) == TRUE) {
			/* LINTED */
			_VIRTTOP = (short)wy;
			goto done;
		}

		if (clby < 0) {
			/* now we have to work, check for ceod */
			clby = _getceod(wy, boty);

			/* check for insert/delete lines */
			if (_virtscr->_use_idl)
				idby = (*_setidln)();
		}

		/* try clear-to-eod */
		if (wy == clby)
			_useceod(wy, boty);

		/* try ins/del lines */
		if (wy == idby) {
			curscr->_cury = cy;
			curscr->_curx = cx;
			(*_useidln)();
			cy = curscr->_cury;
			cx = curscr->_curx;
		}

		if (*bnsch < scrco)
			_updateln(wy);

next:
		*bnsch = _INFINITY;
		*ensch = -1;
	}

	/* do hardware soft labels; if _changed == 2, */
	/* slk's are in clear mode. */
	if (slk && (slk->_changed == TRUE) && !(slk->_win))
		(*_do_slk_ref)();

	/* move cursor */
	wy = _virtscr->_cury;
	wx = _virtscr->_curx;
	if (wy != cy || wx != cx) {
		(void) mvcur(cy, cx, wy, wx);
		/* LINTED */
		cy = (short)wy;
		/* LINTED */
		cx = (short)wx;
	}

	/* reset the flags */
	curscr->_clear = FALSE;
	_virtscr->_use_idl = FALSE;
	_virtscr->_use_idc = TRUE;
	_INPUTPENDING = FALSE;

	/* virtual image is now up-to-date */
	_VIRTTOP = scrli;
	_VIRTBOT = -1;

done :
	curscr->_cury = cy;
	curscr->_curx = cx;
	(void) fflush(SP->term_file);
	return (outchcount);
}

/* Shift appropriate portions of a line to leave space for cookies. */

static	chtype	*
_shove(int wy)
{
	chtype		*wcp, *cp, prev;
	short		curx;
	int		x, cury, didshift;
	static	chtype	*line;
	static	int	length;

	/* allocate space for shifted line */
	if (length < scrco) {
		free(line);
		line = (chtype *) malloc(scrco * sizeof (chtype));
		length = line ? scrco : 0;
	}

	/* no space to do it */
	if (!line)
		return (_virtscr->_y[wy]);

	prev = A_NORMAL;
	cp = line;
	wcp = _virtscr->_y[wy];
	curx = _virtscr->_curx;
	cury = _virtscr->_cury;
	didshift = FALSE;

	for (x = 0; x < scrco; ++x, ++wcp, ++cp) {
		if (_ATTR(*wcp) != prev) {
			/* use existing blank */
			if (_CHAR(*wcp) == ' ')
				*cp = ' ' | _ATTR(*(wcp + 1));
				/* use previous blank */
			else
				if ((x > 0) && _CHAR(*(cp - 1)) == ' ') {
					*(cp - 1) = ' ' | _ATTR(*wcp);
					*cp = *wcp;
				} else {
					if ((curx >= x) && (cury == wy))
						++curx;
					*cp = ' ' | _ATTR(*wcp);
					--wcp;
					didshift = TRUE;
				}
			prev = _ATTR(*cp);
		} else
			*cp = *wcp;
	}

	/* make sure that the end of the line is normal */
	cp = line + scrco - 1;
	if (didshift || (_ATTR(*cp) != A_NORMAL) ||
	    ((wy == scrli - 1) && (_ATTR(*(cp - 1)) != A_NORMAL))) {
		*cp = didshift ? ' ' : _CHAR(*cp);
		if (wy == scrli - 1)
			*(cp - 1) = didshift ? ' ' : _CHAR(*(cp - 1));
	}

	if (wy == cury)
		_virtscr->_curx = curx >= scrco ? scrco - 1 : curx;

	return (line);
}

/*
 * Update a line.
 * Three schemes of coloring are allowed. The first is the usual
 * pen-up/pen-down model. The second is the HP26*-like model.
 * In this case, colorings are specified by intervals, the left
 * side of the interval has the coloring mark, the right side
 * has the end-coloring mark. We assume that clear sequences will
 * clear ALL marks in the affected regions. The second case is
 * signified by the boolean flag ceol_standout_glitch.
 * The third case is for terminals that leave visible cookies on
 * the screen. This last case is at most an approximation of what
 * can be done right.
 */

static	void
_updateln(int wy)
{
	chtype	*wcp, *scp, *wp, *sp, wc, sc;
	int	wx, lastx, x, mtch, idch, blnkx, idcx, video_attrx,
	    color_attrx, maxi, endns, begns, wx_sav, multi_col;
	bool	redraw, changed, didcolor, didvideo;

	redraw = (_virtscr->_firstch[wy] == _REDRAW);
	endns = _ENDNS[wy];
	begns = _BEGNS[wy];

	/* easy case */
	if (!redraw && (_virtscr->_lastch[wy] == _BLANK) && (begns >= scrco))
		return;

	/* line images */
	wcp = magic_cookie_glitch <= 0 ? _virtscr->_y[wy] : _shove(wy);
	scp = curscr->_y[wy];

	/* the interval to be updated */
	if (redraw || magic_cookie_glitch >= 0) {
		wx = 0;
		lastx = scrco;
	} else {
		wx = _virtscr->_firstch[wy];
		lastx = _virtscr->_lastch[wy] == _BLANK ? scrco :
		    _virtscr->_lastch[wy] + 1;
	}

	/* skip equal parts */
	if (!redraw) {
		/* skip the starting equal part */
		wp = wcp + wx;
		sp = scp + wx;
		for (; wx < lastx; ++wx)
			if (*wp++ != *sp++)
				break;
		if (wx >= lastx)
			return;

		/* start update at an entire character */
		for (sp = scp+wx, wp = wcp+wx; wp > wcp; --wp, --sp, --wx)
			if (!ISCBIT(*wp) && !ISCBIT(*sp))
				break;

		/* skip the ending equal part */
		wp = wcp + lastx - 1;
		sp = scp + lastx - 1;
		for (; lastx > wx; --lastx)
			if (*wp-- != *sp--)
				break;
		++wp;
		++wp;
		++sp;
		++sp;
		for (; lastx < scrco; ++wp, ++sp, ++lastx)
			if (!ISCBIT(*wp) && !ISCBIT(*sp))
				break;
	}

	/* place to do clear-eol */
	if (!clr_eol || endns >= lastx)
		blnkx = scrco;
	else
		if (_virtscr->_lastch[wy] == _BLANK)
			blnkx = -1;
		else {
			for (blnkx = lastx - 1, wp = wcp + blnkx;
			    blnkx >= wx; --blnkx, --wp)
				if (_DARKCHAR(*wp))
					break;
			for (sp = scp + blnkx + 1; blnkx < scrco - 1;
			    ++sp, ++blnkx)
				if (!ISCBIT(*sp))
					break;
			if (blnkx + _COST(Clr_eol) >= lastx)
				blnkx = scrco;
		}

	/* on cookie terminals, we may need to do more work */
	if (marks) {
		/* video_attrx = color_attrx = scrco; */
		video_attrx = color_attrx = (lastx >= scrco) ? lastx - 1 :
		    lastx;

		/* find the last video attribute on the line	*/

		wp = wcp + video_attrx;
		for (; video_attrx >= wx; --video_attrx, --wp)
			if (_VIDEO(*wp) != A_NORMAL)
				break;

		/* find the last color attribute on the line	*/

		if (color_marks) {
			wp = wcp + color_attrx;
			for (; color_attrx >= wx; --color_attrx, --wp)
				if (_COLOR(*wp) != A_NORMAL)
					break;
			if (color_attrx < lastx)
				color_attrx++;
		}
		if (video_attrx < lastx)
			video_attrx++;

		if (video_attrx >= scrco)
			--video_attrx;
		if (color_marks && color_attrx >= scrco)
			--color_attrx;
		if (magic_cookie_glitch > 0 && wy == scrli - 1 &&
		    video_attrx == scrco - 1)
			--video_attrx;
		if (color_marks && magic_cookie_glitch > 0 &&
		    wy == scrli - 1 && color_attrx == scrco - 1)
			--color_attrx;
		for (wp = wcp+video_attrx; wp >= wcp+wx; --wp)
			if (!ISCBIT(*wp))
				break;
	}

	/* place for insert/delete chars */
#define	SLACK	4
	if (redraw || (!SP->dchok && !SP->ichok) || !(_virtscr->_use_idc) ||
	    endns < wx || (endns >= lastx && (scrco - lastx) > SLACK)) {
		idcx = scrco;
	} else
		if (!marks)
			idcx = -1;
		else {
			/* on cookie term, only do idch where no attrs */
			/* are used */
			for (idcx = scrco - 1, wp = wcp + idcx; idcx >= wx;
			    --idcx, --wp)
				if (_ATTR(*wp) || _ISMARK1(wy, idcx) ||
				    _ISMARK2(wy, idcx))
					break;
			if (idcx >= scrco - SLACK)
				idcx = scrco;
		}

	if (idcx < lastx && endns >= lastx)
		lastx = scrco;

	/* max amount of insert allow */
	if (idcx == scrco || !SP->ichok)
		maxi = 0;
	else
		if (lastx == scrco)
			maxi = scrco;
		else
			maxi = lastx - (endns + 1);

	/* go */
	wcp += wx;
	scp += wx;
	didvideo = changed = FALSE;
	didcolor = (color_marks) ? FALSE : TRUE;

	while (wx < lastx) {
		/* skip things that are already right */
		if (!redraw) {
			multi_col = 0;
			wx_sav = wx;
			for (; wx < lastx; ++wx, ++wcp, ++scp)
				if (*wcp != *scp)
					break;
			if (wx >= lastx)
				goto done;
			for (; wx > wx_sav; --wx, --wcp, --scp) {
				if (!ISCBIT(*wcp) && !ISCBIT(*scp))
					break;
				multi_col = 1;
			}
		}

		/* try clear-bol, we'll assume exclusive clr_bol */
		if (!changed && !marks && clr_bol && blnkx > wx &&
		    begns >= wx) {
			for (x = wx, wp = wcp; x < lastx; ++x, ++wp)
				if (_DARKCHAR(*wp))
					break;
			/* clearing only whole screen characters */
			for (sp = scp+(x-wx); x >= wx; --x, --sp)
				if (!ISCBIT(*sp))
					break;
			x -= 1;

			if ((x - (redraw ? 0 : begns)) > _COST(Clr_bol)) {
				(void) mvcur(cy, cx, wy, x);
				/* MORE?: colors - mvcur will shuts of */
				/* colors when msgr is not defined */

/* SS: colors */
				if (back_color_erase)
					_turn_off_background();

				_PUTS(clr_bol, 1);
				/* LINTED */
				cy = (short)wy;
				/* LINTED */
				cx = (short)x;

				mtch = x - wx;
				(void) memcpy(scp, wcp,
				    (mtch * sizeof (chtype)));
				wcp += mtch;
				scp += mtch;
				wx = x;
			}
		}

		/* screen image is changing */
		changed = TRUE;

		/* move to the point to start refresh */
		if (cy != wy || cx != wx)
			(void) mvcur(cy, cx, wy, wx);
		/* LINTED */
		cy = (short)wy;
		/* LINTED */
		cx = (short)wx;

		/* update screen image */
		while (wx < lastx) {
			wc = *wcp;
			sc = *scp;

			if (!redraw && !multi_col && wc == sc)
				break;

			/* real video attributes */
			if (marks)
				curscr->_attrs = _ATTR(sc);

			/* blanks only */
			if (wx > blnkx) {
/* SS: colors */
				if (back_color_erase)
					_turn_off_background();

				_PUTS(clr_eol, 1);
				/* LINTED */
				curscr->_curx = (short)wx;
				/* LINTED */
				curscr->_cury = (short)wy;
				(void) wclrtoeol(curscr);

				if (marks && wx > 0 && _ATTR(*(scp - 1)) !=
				    A_NORMAL) {
					_VIDS(A_NORMAL, _ATTR(*(scp - 1)));
					if (_VIDEO(*scp - 1))
						_setmark1(wy, wx, NULL);
					if (_COLOR(*scp - 1))
						_setmark2(wy, wx, NULL);
				}
				goto done;
			}

			/* try insert/delete chars */
			if (wx > idcx && !ISCBIT(*scp) &&
			    (mtch = _useidch(wcp, scp, lastx - wx,
			    maxi, &idch))) {
				maxi -= idch;
				wx += mtch;
				scp += mtch;
				wcp += mtch;
				break;
			}

			/* about to output chars, make sure insert */
			/* mode is off */
			if (SP->phys_irm)
				_OFFINSERT();

			/* color and video attributes */
			if (_ATTR(wc) != curscr->_attrs) {
				bool  color_change = FALSE;
				bool  video_change = FALSE;

				if (marks) {
					if (_VIDEO(wc) !=
					    _VIDEO(curscr->_attrs)) {
						video_change = TRUE;
					}
				}
				if (color_marks) {
					if (_COLOR(wc) !=
					    _COLOR(curscr->_attrs)) {
						color_change = TRUE;
					}
				}

				/* the following may occurs when, for */
				/* example the application */
				/* is written for color terminal and then */
				/* run on a monocrome  */

				if (marks && !video_change && !color_change)
					goto no_change;

				/* prevent spilling out of line */
				if (marks && !(didcolor && didvideo)) {
				    if ((video_change && !_ISMARK1(wy,
					video_attrx)) || (color_change &&
					!_ISMARK2(wy, color_attrx))) {
					    int    tempx;
					    chtype sa = curscr->_attrs;
					    bool   first  = FALSE;
					    bool   second = FALSE;

					    if (!didvideo && video_change &&
						!_ISMARK1(wy, video_attrx)) {
						didvideo = TRUE;
						(void) mvcur(wy, wx,
						    wy, video_attrx);
						_VIDS(_VIDEO(_virtscr->_y[wy]
						    [video_attrx]),
						    _VIDEO(_virtscr->_y[wy]
						    [video_attrx-1]));
						_setmark1(wy, video_attrx,
						    NULL);
						first = TRUE;
					    }

				if (!didcolor && color_change &&
				    !_ISMARK2(wy, color_attrx)) {
					didcolor = TRUE;
					tempx = first ? video_attrx : wx;
					if (tempx != color_attrx)
						(void) mvcur(wy, tempx, wy,
						    color_attrx);
				/*
				 * sc = _COLOR(curscr->_y[wy][color_attrx]);
				 * _VIDS(sc, (~sc & A_COLOR));
				 */
					_VIDS(_COLOR(_virtscr->_y[wy]
					    [color_attrx]),
					    _COLOR(_virtscr->_y[wy]
					    [color_attrx-1]));
					_setmark2(wy, color_attrx, NULL);
					second = TRUE;
				}
				(void) mvcur(wy, (second ? color_attrx :
				    video_attrx), wy, wx);
				curscr->_attrs = sa;
			    }
			}

			_VIDS(_ATTR(wc), curscr->_attrs);

			/* on cookie terminals mark the interval */
			if (video_change)
				_setmark1(wy, wx, scp);
			if (color_change)
				_setmark2(wy, wx, scp);
		}

		/* end-of-line */
no_change:
		x = 1;
		if (_scrmax > 1)
			x = _curs_scrwidth[TYPE(RBYTE(wc))];
		if (wx == scrco - x) {
			_rmargin(wx);
			goto done;
		}

		if (transparent_underline && erase_overstrike &&
		    _CHAR(wc) == '_') {
			(void) _outch(' ');
			(void) mvcur(wy, wx + 1, wy, wx);
		}

		/* put out the character */
		(void) _outwch(tilde_glitch && _CHAR(wc) == '~' ? '`' : wc);

		*scp++ = wc;
		wcp++;
		wx++;
		cx++;
		/* output entire multi-byte chars */
		while (wx < lastx && ISCBIT(*wcp)) {
			(void) _outwch(*wcp);
			*scp++ = *wcp++;
			wx++;
			cx++;


		}
		}
	}

done:
	if (changed) {
		/* update the blank structure */
		for (wx = 0, scp = curscr->_y[wy]; wx < scrco; ++wx, ++scp)
			if (_DARKCHAR(*scp))
				break;
		/* LINTED */
		_BEGNS[wy] = (short)wx;
		if (wx == scrco)
			_ENDNS[wy] = -1;
		else {
			wx = scrco - 1;
			scp = curscr->_y[wy] + wx;
			for (; wx >= 0; --wx, --scp)
				if (_DARKCHAR(*scp))
					break;
			/* LINTED */
			_ENDNS[wy] = (short)wx;
		}

		/* update the hash structure */
		_CURHASH[wy] = _BEGNS[wy] < scrco ? _NOHASH : 0;
	}
}

/*
 * See if a left or right shift is apppropriate
 * This routine is called only if !cookie_glitch or no video attributes
 * are used in the affected part.
 * The main idea is to find a longest common substring which is a
 * prefix of one of 'wcp' or 'scp', then either delete or
 * insert depending on where the prefix is.
 *
 * wcp : what we want the screen to look like
 * scp : what the screen looks like now
 * length: the length to be updated
 * maxi: maximum possible insert amount
 * id; *id returns the amount of insert/delete
 *
 * Return the number of chars matched after the shift.
 */

static int
_useidch(chtype *wcp, chtype *scp, int length, int maxi, int *id)
{
	int	x1, x2, blnk, idch, cost, cost_ich1, match;
	chtype	wc;

	/* try deletion */
	if (SP->dchok && _CHAR(*wcp) != ' ') {
		if ((match = _prefix(wcp, scp, length, length / 2, &idch)) > 0)
			cost = _COST(dcfixed) + (parm_dch ? _COST(Parm_dch) :
			    _COST(Delete_character) * idch);
		else
			cost = _INFINITY;

		if (match >= cost) {
/* SS: colors */
			if (back_color_erase)
				_turn_off_background();

			if (SP->dmode) {
				if (SP->sid_equal) {
					if (!(SP->phys_irm))
						_ONINSERT();
				} else {
					if (SP->phys_irm)
						_OFFINSERT();
					_PUTS(enter_delete_mode, 1);
				}
			}

			if (parm_dch)
				_PUTS(tparm_p1(parm_dch, idch), 1);
			else
				for (x1 = 0; x1 < idch; ++x1)
					_PUTS(delete_character, 1);

			if (SP->dmode) {
				if (SP->eid_equal)
					SP->phys_irm = FALSE;
				_PUTS(exit_delete_mode, 1);
			}

			/* update screen image */
			for (x1 = 0, x2 = idch; x2 < length; ++x1, ++x2)
				scp[x1] = scp[x2];
			for (; x1 < length; ++x1)
				scp[x1] = ' ';

			*id = -idch;
			return (match);
		}
	}

	/* no insertion wanted or possible */
	if (!(SP->ichok) || _CHAR(*scp) == ' ')
		return (0);

	/* see if insertion is worth it */
	maxi = (idch = length / 2) < maxi ? idch : maxi;
	if ((match = _prefix(scp, wcp, length, maxi, &idch)) <= 0)
		return (0);

	/* see if inserting blanks only */
	for (blnk = 0; blnk < idch; ++blnk)
		if (wcp[blnk] != ' ') {
			blnk = 0;
			break;
		}

	/* see if doing insertion is worth it */
	cost_ich1 = idch * _COST(Insert_character);
	if (SP->imode) {
		cost = SP->phys_irm ? 0 : _COST(icfixed);
		if (blnk > _COST(Parm_ich) && _COST(Parm_ich) < cost_ich1)
			cost += _COST(Parm_ich);
		else
			if (insert_character)
				cost += cost_ich1;
	} else {
		if (parm_ich && _COST(Parm_ich) < cost_ich1)
			cost = _COST(Parm_ich);
		else
			cost = cost_ich1;
	}
	if ((cost - blnk) > match)
		return (0);

	/* perform the insertions */

	/* SS: colors */
	if (back_color_erase)
		_turn_off_background();

	if (SP->imode) {
		if (!SP->phys_irm)
			_ONINSERT();
		if (blnk > _COST(Parm_ich) && _COST(Parm_ich) < cost_ich1)
			_PUTS(tparm_p1(parm_ich, idch), 1);
		else
			if (insert_character)
				goto do_insert_char;
			else
				/* so that we'll do real char insertions */
				blnk = 0;
	} else {
		if (parm_ich && _COST(Parm_ich) < cost_ich1)
			_PUTS(tparm_p1(parm_ich, idch), 1);
		else {
do_insert_char:
			for (x1 = 0; x1 < idch; ++x1)
				_PUTS(insert_character, 1);
		}
	}

	/* inserting desired characters */
	if (!blnk)
		for (x1 = 0; x1 < idch; ++x1) {
			wc = wcp[x1];
			if (_ATTR(wc) != curscr->_attrs)
				_VIDS(_ATTR(wc), curscr->_attrs);
			(void) _outwch(_CHAR(wc) == '~' &&
			    tilde_glitch ? '`' : wc);
			++cx;
		}

	/* update the screen image */
	for (x1 = length - 1, x2 = length - idch - 1; x2 >= 0; --x1, --x2)
		scp[x1] = scp[x2];
	(void) memcpy(scp, wcp, idch * sizeof (chtype));

	*id = idch;
	return (match + idch);
}

/*
 * Find a substring of s2 that match a prefix of s1.
 * The substring is such that:
 * 	1. it does not start with an element
 *	   that is in perfect alignment with one in s1 and
 * 	2: it is at least as long as the displacement.
 *
 * length: the length of s1, s2.
 * maxs: only search for match in [1,maxs]  of s2.
 * begm: *begm returns where the match begins.
 *
 * Return the number of matches.
 */

static int
_prefix(chtype *s1, chtype *s2, int length, int maxs, int *begm)
{
	int	m, n, k;

	n = 0;
	for (m = 1; m <= maxs; ++m)
		/* testing for s1[m] != s2[m] is condition 1 */
		if (s1[0] == s2[m] && s1[m] != s2[m]) {
			/* see if it's long enough (condition 2) */
			for (k = 2 * m - 1; k > m; --k)
				if (s1[k - m] != s2[k])
					break;
			/* found a match with a good length */
			if (k == m) {
				*begm = m;

				/* count the # of matches */
				s2 += m;
				length -= m;
				for (n = m; n < length; ++n)
					if (s1[n] != s2[n])
						break;
				goto done;
			}
		}

done:
	return (n);
}

/* Set video markers for cookie terminal. */

static void
_setmark1(int y, int x, chtype *s)
{
	long	a;

	/* set the mark map */
	marks[y][x / BITSPERBYTE] |= (1 << (x % BITSPERBYTE));

	if (s) {
		a  = _VIDEO(curscr->_attrs);

		/* set the video attr of the first char here */
		/* LINTED */
		*s = _CHAR(*s) | _COLOR(*s) | a;

		/* now the video attr of the rest of the affected interval */
		for (x += 1, s += 1; x < scrco; ++x, ++s)
			if (_ISMARK1(y, x))
				break;
			else
				/* LINTED */
				*s = _CHAR(*s) | _COLOR(*s) | a;
	}
}

/* Set color markers for cookie terminal. */

static void
_setmark2(int y, int x, chtype *s)
{
	long	a;

	/* set the mark map */
	color_marks[y][x / BITSPERBYTE] |= (1 << (x % BITSPERBYTE));

	if (s) {
		a  = _COLOR(curscr->_attrs);

		/* set the video attr of the first char here */
		/* LINTED */
		*s = _CHAR(*s) | _VIDEO(*s) | a;

		/* now the video attr of the rest of the affected interval */
		for (x += 1, s += 1; x < scrco; ++x, ++s)
			if (_ISMARK2(y, x))
				break;
			else
				/* LINTED */
				*s = _CHAR(*s) | _VIDEO(*s) | a;
	}
}


/* At the right margin various weird things can happen.  We treat them here. */

/* At the right margin various weird things can happen.  We treat them here. */

static void
_rmargin(int wx)
{
	int	x, w, ix;
	chtype	sc;
	chtype	*wcp =	_virtscr->_y[cy];

	/* screen may scroll */
	if (cy == scrli - 1) {
		/* can't do anything */
		if (!SP->ichok)
			return;

		/* the width of the new character */
		w = _curs_scrwidth[TYPE(RBYTE(wcp[wx]))];
		/* the place to put it without causing scrolling */
		for (x = wx - 1; x > 0; --x)
			if (!ISCBIT(wcp[x]))
				break;
		sc = curscr->_y[cy][x];

		(void) mvcur(cy, cx, cy, x);
		if (_ATTR(wcp[wx]) != curscr->_attrs)
			_VIDS(_ATTR(wcp[wx]), curscr->_attrs);
		(void) _outwch(tilde_glitch &&
		    _CHAR(wcp[wx]) == '~' ? '`' : wcp[wx]);

		for (ix = wx + 1; ix < scrco; ++ix) {
			(void) _outwch(wcp[ix]);
		}

		/* insert sc back in and push wcp[wx] right */
		(void) mvcur(cy, x+w, cy, x);

		/* SS: colors */
		if (back_color_erase)
			_turn_off_background();

		if (SP->imode && !SP->phys_irm)
			_ONINSERT();
		/* width of the old character that was overwritten */
		w = _curs_scrwidth[TYPE(RBYTE(curscr->_y[cy][x]))];

		if (insert_character)
			for (ix = 0; ix < w; ++ix)
				_PUTS(insert_character, 1);
		else
			if (parm_ich && !SP->imode)
				_PUTS(tparm_p1(parm_ich, w), 1);

		if (_ATTR(sc) != curscr->_attrs)
			_VIDS(_ATTR(sc), curscr->_attrs);
		for (ix = x; w > 0; --w, ++ix)
			(void) _outwch(curscr->_y[cy][ix]);

		/* make sure the video attrs are ok */
		if (marks && (_ATTR(sc) || _ATTR(wcp[wx])))
			_VIDS(_ATTR(wcp[wx]), ~_ATTR(sc));

		/* update screen image */
		/* LINTED */
		cx = (short)wx;
		curscr->_y[cy][wx] = wcp[wx];
		for (x = wx + 1; x < scrco; ++x) {
			(void) _outwch(wcp[x]);
			curscr->_y[cy][x] = wcp[x];
		}
		return;
	}

	/* put char out and update screen image */
	(void) _outwch(tilde_glitch && _CHAR(wcp[wx]) == '~' ? '`' : wcp[wx]);


	curscr->_y[cy][wx] = wcp[wx];

	for (x = wx + 1; x < scrco; ++x) {
		(void) _outwch(wcp[x]);
		curscr->_y[cy][x] = wcp[x];
	}

	/* make sure that wrap-around happens */
	if (!auto_right_margin || eat_newline_glitch) {
		(void) _outch('\r');
		(void) _outch('\n');
	}
	cx = 0;
	++cy;
}

/*
 * Find the top-most line to do clear-to-eod.
 *
 * topy, boty: the region to consider
 */

static int
_getceod(int topy, int boty)
{
	chtype	*wcp, *ecp;
	int	wy;
	short	*begch, *endch, *begns;

	/* do nothing */
	if ((topy + 1) >= boty)
		return (boty);

	wy = boty - 1;
	begch = _virtscr->_firstch + wy;
	endch = _virtscr->_lastch + wy;
	begns = _BEGNS + wy;

	for (; wy >= topy; --wy, --begch, --endch, --begns) {
		if (*endch == _BLANK || (*begch >= scrco && *begns >= scrco))
			continue;

		wcp = _virtscr->_y[wy];
		ecp = wcp + scrco;
		for (; wcp < ecp; ++wcp)
			if (_DARKCHAR(*wcp))
			break;
		if (wcp != ecp)
			break;

		*endch = _BLANK;
	}

	return (wy + 1);
}

/* Use hardware clear-to-bottom. */

static void
_useceod(int topy, int boty)
{
	short	*begns, *begch;

	/* skip lines already blanked */
	begch = _virtscr->_firstch + topy;
	begns = _BEGNS + topy;
	for (; topy < boty; ++topy, ++begns, ++begch)
		if (*begns < scrco || *begch == _REDRAW)
			break;
		else
			*begch = _INFINITY;

	/* nothing to do */
	if (topy + 1 >= boty)
		return;

	/* see if bottom is clear */
	for (begns = _BEGNS + boty; boty < scrli; ++boty, ++begns)
		if (*begns < scrco)
			return;

	/* use clear-screen if appropriate */
	if (topy == 0) {
		/* SS: colors */
		if (back_color_erase)
			_turn_off_background();

		_PUTS(clear_screen, scrli);
		cy = 0; cx = 0;
		(void) werase(curscr);
	} else {

		/* use clear-to-end-of-display or delete lines */
		if (clr_eos || (parm_delete_line && !memory_below)) {
			(void) mvcur(cy, cx, topy, 0);
			/* LINTED */
			cy = (short)topy;
			cx = 0;
			/* SS: colors */
			if (back_color_erase)
				_turn_off_background();
			_PUTS(clr_eos ? clr_eos : tparm_p1(parm_delete_line,
			    scrli - topy), scrli - topy);

			/* update curscr */
			/* LINTED */
			curscr->_cury = (short)topy;
			curscr->_curx = 0;
			(void) wclrtobot(curscr);
		} else {
			/* no hardware support */
			return;
		}
	}

	/* correct the update structure */
	(void) wtouchln(_virtscr, topy, scrli, FALSE);
}


static void
_turn_off_background(void)
{
	/* this routine turn the background color to zero.  This need to be */
	/* done only in forllowing cases:				*/
	/*  1) We are using Tek type terminal (which has bce terminfo	*/
	/*	variable)  */
	/*  2) The current background is not already zero		*/

	if (set_background && cur_term->_cur_pair.background > 0) {
		_PUTS(orig_pair, 1);
		cur_term->_cur_pair.foreground = -1;
		cur_term->_cur_pair.background = -1;
		curscr->_attrs &= ~A_COLOR;
	}
}