freebsd_amp_hwpstate/usr.bin/vi/svi/svi_refresh.c

/*-
 * Copyright (c) 1992, 1993, 1994
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
static char sccsid[] = "@(#)svi_refresh.c	8.62 (Berkeley) 8/17/94";
#endif /* not lint */

#include <sys/types.h>
#include <sys/queue.h>
#include <sys/time.h>

#include <bitstring.h>
#include <ctype.h>
#include <limits.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>

#include "compat.h"
#include <curses.h>
#include <db.h>
#include <regex.h>

#include "vi.h"
#include "svi_screen.h"
#include "../sex/sex_screen.h"

static int	svi_modeline __P((SCR *, EXF *));

int
svi_refresh(sp, ep)
	SCR *sp;
	EXF *ep;
{
	SCR *tsp;
	u_int paintbits;

	/*
	 * 1: Resize the screen.
	 *
	 * Notice that a resize is requested, and set up everything so that
	 * the file gets reinitialized.  Done here, instead of in the vi loop
	 * because there may be other initialization that other screens need
	 * to do.  The actual changing of the row/column values was done by
	 * calling the ex options code which put them into the environment,
	 * which is used by curses.  Stupid, but ugly.
	 */
	if (F_ISSET(sp, S_RESIZE)) {
		/* Reinitialize curses. */
		if (svi_curses_end(sp) || svi_curses_init(sp))
			return (1);

		/* Invalidate the line size cache. */
		SVI_SCR_CFLUSH(SVP(sp));

		/*
		 * Fill the map, incidentally losing any svi_line()
		 * cached information.
		 */
		if (svi_sm_fill(sp, ep, sp->lno, P_FILL))
			return (1);
		F_CLR(sp, S_RESIZE | S_REFORMAT);
		F_SET(sp, S_REDRAW);
	}

	/*
	 * 2: S_REFRESH
	 *
	 * If S_REFRESH is set in the current screen, repaint everything
	 * that we can find.
	 */
	if (F_ISSET(sp, S_REFRESH))
		for (tsp = sp->gp->dq.cqh_first;
		    tsp != (void *)&sp->gp->dq; tsp = tsp->q.cqe_next)
			if (tsp != sp)
				F_SET(tsp, S_REDRAW);
	/*
	 * 3: Related or dirtied screens, or screens with messages.
	 *
	 * If related screens share a view into a file, they may have been
	 * modified as well.  Refresh any screens with paint or dirty bits
	 * set, or where messages are waiting.  Finally, if we refresh any
	 * screens other than the current one, the cursor will be trashed.
	 */
	paintbits = S_REDRAW | S_REFORMAT | S_REFRESH;
	if (O_ISSET(sp, O_NUMBER))
		paintbits |= S_RENUMBER;
	for (tsp = sp->gp->dq.cqh_first;
	    tsp != (void *)&sp->gp->dq; tsp = tsp->q.cqe_next)
		if (tsp != sp &&
		    (F_ISSET(tsp, paintbits) ||
		    F_ISSET(SVP(tsp), SVI_SCREENDIRTY) ||
		    tsp->msgq.lh_first != NULL &&
		    !F_ISSET(tsp->msgq.lh_first, M_EMPTY))) {
			(void)svi_paint(tsp, tsp->ep);
			F_CLR(SVP(tsp), SVI_SCREENDIRTY);
			F_SET(SVP(sp), SVI_CUR_INVALID);
		}

	/*
	 * 4: Refresh the current screen.
	 *
	 * Always refresh the current screen, it may be a cursor movement.
	 * Also, always do it last -- that way, S_REFRESH can be set in
	 * the current screen only, and the screen won't flash.
	 */
	F_CLR(sp, SVI_SCREENDIRTY);
	return (svi_paint(sp, ep));
}

/*
 * svi_paint --
 *	This is the guts of the vi curses screen code.  The idea is that
 *	the SCR structure passed in contains the new coordinates of the
 *	screen.  What makes this hard is that we don't know how big
 *	characters are, doing input can put the cursor in illegal places,
 *	and we're frantically trying to avoid repainting unless it's
 *	absolutely necessary.  If you change this code, you'd better know
 *	what you're doing.  It's subtle and quick to anger.
 */
int
svi_paint(sp, ep)
	SCR *sp;
	EXF *ep;
{
	SMAP *smp, tmp;
	SVI_PRIVATE *svp;
	recno_t lastline, lcnt;
	size_t cwtotal, cnt, len, x, y;
	int ch, didpaint, leftright_warp;
	char *p;

#define	 LNO	sp->lno
#define	OLNO	svp->olno
#define	 CNO	sp->cno
#define	OCNO	svp->ocno
#define	SCNO	svp->sc_col

	didpaint = leftright_warp = 0;
	svp = SVP(sp);

	/*
	 * 1: Reformat the lines.
	 *
	 * If the lines themselves have changed (:set list, for example),
	 * fill in the map from scratch.  Adjust the screen that's being
	 * displayed if the leftright flag is set.
	 */
	if (F_ISSET(sp, S_REFORMAT)) {
		/* Invalidate the line size cache. */
		SVI_SCR_CFLUSH(SVP(sp));

		/* Toss svi_line() cached information. */
		if (svi_sm_fill(sp, ep, HMAP->lno, P_TOP))
			return (1);
		if (O_ISSET(sp, O_LEFTRIGHT) &&
		    (cnt = svi_opt_screens(sp, ep, LNO, &CNO)) != 1)
			for (smp = HMAP; smp <= TMAP; ++smp)
				smp->off = cnt;
		F_CLR(sp, S_REFORMAT);
		F_SET(sp, S_REDRAW);
	}

	/*
	 * 2: Line movement.
	 *
	 * Line changes can cause the top line to change as well.  As
	 * before, if the movement is large, the screen is repainted.
	 *
	 * 2a: Tiny screens.
	 *
	 * Tiny screens cannot be permitted into the "scrolling" parts of
	 * the smap code for two reasons.  If the screen size is 1 line,
	 * HMAP == TMAP and the code will quickly drop core.  If the screen
	 * size is 2, none of the divisions by 2 will work, and scrolling
	 * won't work.  In fact, because no line change will be less than
	 * HALFTEXT(sp), we always ending up "filling" the map, with a
	 * P_MIDDLE flag, which isn't what the user wanted.  Tiny screens
	 * can go into the "fill" portions of the smap code, however.
	 */
	if (sp->t_rows <= 2) {
		if (LNO < HMAP->lno) {
			if (svi_sm_fill(sp, ep, LNO, P_TOP))
				return (1);
		} else if (LNO > TMAP->lno)
			if (svi_sm_fill(sp, ep, LNO, P_BOTTOM))
				return (1);
		if (sp->t_rows == 1) {
			HMAP->off = svi_opt_screens(sp, ep, LNO, &CNO);
			goto paint;
		}
		F_SET(sp, S_REDRAW);
		goto adjust;
	}

	/*
	 * 2b: Small screens.
	 *
	 * Users can use the window, w300, w1200 and w9600 options to make
	 * the screen artificially small.  The behavior of these options
	 * in the historic vi wasn't all that consistent, and, in fact, it
	 * was never documented how various screen movements affected the
	 * screen size.  Generally, one of three things would happen:
	 *	1: The screen would expand in size, showing the line
	 *	2: The screen would scroll, showing the line
	 *	3: The screen would compress to its smallest size and
	 *		repaint.
	 * In general, scrolling didn't cause compression (200^D was handled
	 * the same as ^D), movement to a specific line would (:N where N
	 * was 1 line below the screen caused a screen compress), and cursor
	 * movement would scroll if it was 11 lines or less, and compress if
	 * it was more than 11 lines.  (And, no, I have no idea where the 11
	 * comes from.)
	 *
	 * What we do is try and figure out if the line is less than half of
	 * a full screen away.  If it is, we expand the screen if there's
	 * room, and then scroll as necessary.  The alternative is to compress
	 * and repaint.
	 *
	 * !!!
	 * This code is a special case from beginning to end.  Unfortunately,
	 * home modems are still slow enough that it's worth having.
	 *
	 * XXX
	 * If the line a really long one, i.e. part of the line is on the
	 * screen but the column offset is not, we'll end up in the adjust
	 * code, when we should probably have compressed the screen.
	 */
	if (ISSMALLSCREEN(sp))
		if (LNO < HMAP->lno) {
			lcnt = svi_sm_nlines(sp, ep, HMAP, LNO, sp->t_maxrows);
			if (lcnt <= HALFSCREEN(sp))
				for (; lcnt && sp->t_rows != sp->t_maxrows;
				     --lcnt, ++sp->t_rows) {
					++TMAP;
					if (svi_sm_1down(sp, ep))
						return (1);
				}
			else
				goto small_fill;
		} else if (LNO > TMAP->lno) {
			lcnt = svi_sm_nlines(sp, ep, TMAP, LNO, sp->t_maxrows);
			if (lcnt <= HALFSCREEN(sp))
				for (; lcnt && sp->t_rows != sp->t_maxrows;
				     --lcnt, ++sp->t_rows) {
					if (svi_sm_next(sp, ep, TMAP, TMAP + 1))
						return (1);
					++TMAP;
					if (svi_line(sp, ep, TMAP, NULL, NULL))
						return (1);
				}
			else {
small_fill:			MOVE(sp, INFOLINE(sp), 0);
				clrtoeol();
				for (; sp->t_rows > sp->t_minrows;
				    --sp->t_rows, --TMAP) {
					MOVE(sp, TMAP - HMAP, 0);
					clrtoeol();
				}
				if (svi_sm_fill(sp, ep, LNO, P_FILL))
					return (1);
				F_SET(sp, S_REDRAW);
				goto adjust;
			}
		}

	/*
	 * 3a: Line down, or current screen.
	 */
	if (LNO >= HMAP->lno) {
		/* Current screen. */
		if (LNO <= TMAP->lno)
			goto adjust;

		/*
		 * If less than half a screen above the line, scroll down
		 * until the line is on the screen.
		 */
		lcnt = svi_sm_nlines(sp, ep, TMAP, LNO, HALFTEXT(sp));
		if (lcnt < HALFTEXT(sp)) {
			while (lcnt--)
				if (svi_sm_1up(sp, ep))
					return (1);
			goto adjust;
		}
		goto bottom;
	}

	/*
	 * 3b: Line up.
	 */
	lcnt = svi_sm_nlines(sp, ep, HMAP, LNO, HALFTEXT(sp));
	if (lcnt < HALFTEXT(sp)) {
		/*
		 * If less than half a screen below the line, scroll up until
		 * the line is the first line on the screen.  Special check so
		 * that if the screen has been emptied, we refill it.
		 */
		if (file_gline(sp, ep, HMAP->lno, &len) != NULL) {
			while (lcnt--)
				if (svi_sm_1down(sp, ep))
					return (1);
			goto adjust;
		}

		/*
		 * If less than a full screen from the bottom of the file,
		 * put the last line of the file on the bottom of the screen.
		 */
bottom:		if (file_lline(sp, ep, &lastline))
			return (1);
		tmp.lno = LNO;
		tmp.off = 1;
		lcnt = svi_sm_nlines(sp, ep, &tmp, lastline, sp->t_rows);
		if (lcnt < sp->t_rows) {
			if (svi_sm_fill(sp, ep, lastline, P_BOTTOM))
				return (1);
			F_SET(sp, S_REDRAW);
			goto adjust;
		}
		/* It's not close, just put the line in the middle. */
		goto middle;
	}

	/*
	 * If less than half a screen from the top of the file, put the first
	 * line of the file at the top of the screen.  Otherwise, put the line
	 * in the middle of the screen.
	 */
	tmp.lno = 1;
	tmp.off = 1;
	lcnt = svi_sm_nlines(sp, ep, &tmp, LNO, HALFTEXT(sp));
	if (lcnt < HALFTEXT(sp)) {
		if (svi_sm_fill(sp, ep, 1, P_TOP))
			return (1);
	} else
middle:		if (svi_sm_fill(sp, ep, LNO, P_MIDDLE))
			return (1);
	F_SET(sp, S_REDRAW);

	/*
	 * At this point we know part of the line is on the screen.  Since
	 * scrolling is done using logical lines, not physical, all of the
	 * line may not be on the screen.  While that's not necessarily bad,
	 * if the part the cursor is on isn't there, we're going to lose.
	 * This can be tricky; if the line covers the entire screen, lno
	 * may be the same as both ends of the map, that's why we test BOTH
	 * the top and the bottom of the map.  This isn't a problem for
	 * left-right scrolling, the cursor movement code handles the problem.
	 *
	 * There's a performance issue here if editing *really* long lines.
	 * This gets to the right spot by scrolling, and, in a binary, by
	 * scrolling hundreds of lines.  If the adjustment looks like it's
	 * going to be a serious problem, refill the screen and repaint.
	 */
adjust:	if (!O_ISSET(sp, O_LEFTRIGHT) &&
	    (LNO == HMAP->lno || LNO == TMAP->lno)) {
		cnt = svi_opt_screens(sp, ep, LNO, &CNO);
		if (LNO == HMAP->lno && cnt < HMAP->off)
			if ((HMAP->off - cnt) > HALFTEXT(sp)) {
				HMAP->off = cnt;
				svi_sm_fill(sp, ep, OOBLNO, P_TOP);
				F_SET(sp, S_REDRAW);
			} else
				while (cnt < HMAP->off)
					if (svi_sm_1down(sp, ep))
						return (1);
		if (LNO == TMAP->lno && cnt > TMAP->off)
			if ((cnt - TMAP->off) > HALFTEXT(sp)) {
				TMAP->off = cnt;
				svi_sm_fill(sp, ep, OOBLNO, P_BOTTOM);
				F_SET(sp, S_REDRAW);
			} else
				while (cnt > TMAP->off)
					if (svi_sm_1up(sp, ep))
						return (1);
	}

	/*
	 * If the screen needs to be repainted, skip cursor optimization.
	 * However, in the code above we skipped leftright scrolling on
	 * the grounds that the cursor code would handle it.  Make sure
	 * the right screen is up.
	 */
	if (F_ISSET(sp, S_REDRAW)) {
		if (O_ISSET(sp, O_LEFTRIGHT)) {
			cnt = svi_opt_screens(sp, ep, LNO, &CNO);
			if (HMAP->off != cnt)
				for (smp = HMAP; smp <= TMAP; ++smp)
					smp->off = cnt;
		}
		goto paint;
	}

	/*
	 * 4: Cursor movements.
	 *
	 * Decide cursor position.  If the line has changed, the cursor has
	 * moved over a tab, or don't know where the cursor was, reparse the
	 * line.  Otherwise, we've just moved over fixed-width characters,
	 * and can calculate the left/right scrolling and cursor movement
	 * without reparsing the line.  Note that we don't know which (if any)
	 * of the characters between the old and new cursor positions changed.
	 *
	 * XXX
	 * With some work, it should be possible to handle tabs quickly, at
	 * least in obvious situations, like moving right and encountering
	 * a tab, without reparsing the whole line.
	 */

	/* If the line we're working with has changed, reparse. */
	if (F_ISSET(SVP(sp), SVI_CUR_INVALID) || LNO != OLNO) {
		F_CLR(SVP(sp), SVI_CUR_INVALID);
		goto slow;
	}

	/* Otherwise, if nothing's changed, go fast. */
	if (CNO == OCNO)
		goto fast;

	/*
	 * Get the current line.  If this fails, we either have an empty
	 * file and can just repaint, or there's a real problem.  This
	 * isn't a performance issue because there aren't any ways to get
	 * here repeatedly.
	 */
	if ((p = file_gline(sp, ep, LNO, &len)) == NULL) {
		if (file_lline(sp, ep, &lastline))
			return (1);
		if (lastline == 0)
			goto slow;
		GETLINE_ERR(sp, LNO);
		return (1);
	}

#ifdef DEBUG
	/* This is just a test. */
	if (CNO >= len && len != 0) {
		msgq(sp, M_ERR, "Error: %s/%d: cno (%u) >= len (%u)",
		     tail(__FILE__), __LINE__, CNO, len);
		return (1);
	}
#endif
	/*
	 * The basic scheme here is to look at the characters in between
	 * the old and new positions and decide how big they are on the
	 * screen, and therefore, how many screen positions to move.
	 */
	if (CNO < OCNO) {
		/*
		 * 4a: Cursor moved left.
		 *
		 * Point to the old character.  The old cursor position can
		 * be past EOL if, for example, we just deleted the rest of
		 * the line.  In this case, since we don't know the width of
		 * the characters we traversed, we have to do it slowly.
		 */
		p += OCNO;
		cnt = (OCNO - CNO) + 1;
		if (OCNO >= len)
			goto slow;

		/*
		 * Quick sanity check -- it's hard to figure out exactly when
		 * we cross a screen boundary as we do in the cursor right
		 * movement.  If cnt is so large that we're going to cross the
		 * boundary no matter what, stop now.
		 */
		if (SCNO + 1 + MAX_CHARACTER_COLUMNS < cnt)
			goto lscreen;

		/*
		 * Count up the widths of the characters.  If it's a tab
		 * character, go do it the the slow way.
		 */
		for (cwtotal = 0; cnt--; cwtotal += KEY_LEN(sp, ch))
			if ((ch = *(u_char *)p--) == '\t')
				goto slow;

		/*
		 * Decrement the screen cursor by the total width of the
		 * characters minus 1.
		 */
		cwtotal -= 1;

		/*
		 * If we're moving left, and there's a wide character in the
		 * current position, go to the end of the character.
		 */
		if (KEY_LEN(sp, ch) > 1)
			cwtotal -= KEY_LEN(sp, ch) - 1;

		/*
		 * If the new column moved us off of the current logical line,
		 * calculate a new one.  If doing leftright scrolling, we've
		 * moved off of the current screen, as well.  Since most files
		 * don't have more than two screens, we optimize moving from
		 * screen 2 to screen 1.
		 */
		if (SCNO < cwtotal) {
lscreen:		if (O_ISSET(sp, O_LEFTRIGHT)) {
				cnt = HMAP->off == 2 ? 1 :
				    svi_opt_screens(sp, ep, LNO, &CNO);
				for (smp = HMAP; smp <= TMAP; ++smp)
					smp->off = cnt;
				leftright_warp = 1;
				goto paint;
			}
			goto slow;
		}
		SCNO -= cwtotal;
	} else {
		/*
		 * 4b: Cursor moved right.
		 *
		 * Point to the first character to the right.
		 */
		p += OCNO + 1;
		cnt = CNO - OCNO;

		/*
		 * Count up the widths of the characters.  If it's a tab
		 * character, go do it the the slow way.  If we cross a
		 * screen boundary, we can quit.
		 */
		for (cwtotal = SCNO; cnt--;) {
			if ((ch = *(u_char *)p++) == '\t')
				goto slow;
			if ((cwtotal += KEY_LEN(sp, ch)) >= SCREEN_COLS(sp))
				break;
		}

		/*
		 * Increment the screen cursor by the total width of the
		 * characters.
		 */
		SCNO = cwtotal;

		/* See screen change comment in section 4a. */
		if (SCNO >= SCREEN_COLS(sp)) {
			if (O_ISSET(sp, O_LEFTRIGHT)) {
				cnt = svi_opt_screens(sp, ep, LNO, &CNO);
				for (smp = HMAP; smp <= TMAP; ++smp)
					smp->off = cnt;
				leftright_warp = 1;
				goto paint;
			}
			goto slow;
		}
	}

	/*
	 * 4c: Fast cursor update.
	 *
	 * Retrieve the current cursor position, and correct it
	 * for split screens.
	 */
fast:	getyx(stdscr, y, x);
	y -= sp->woff;
	goto number;

	/*
	 * 4d: Slow cursor update.
	 *
	 * Walk through the map and find the current line.  If doing left-right
	 * scrolling and the cursor movement has changed the screen displayed,
	 * scroll the screen left or right, unless we're updating the info line
	 * in which case we just scroll that one line.  Then update the screen
	 * lines for this file line until we have a new screen cursor position.
	 */
slow:	for (smp = HMAP; smp->lno != LNO; ++smp);
	if (O_ISSET(sp, O_LEFTRIGHT)) {
		cnt = svi_opt_screens(sp, ep, LNO, &CNO) % SCREEN_COLS(sp);
		if (cnt != HMAP->off) {
			if (ISINFOLINE(sp, smp))
				smp->off = cnt;
			else {
				for (smp = HMAP; smp <= TMAP; ++smp)
					smp->off = cnt;
				leftright_warp = 1;
			}
			goto paint;
		}
	}
	for (y = -1; smp <= TMAP && smp->lno == LNO; ++smp) {
		if (svi_line(sp, ep, smp, &y, &SCNO))
			return (1);
		if (y != -1)
			break;
	}
	goto number;

	/*
	 * 5: Repaint the entire screen.
	 *
	 * Lost big, do what you have to do.  We flush the cache as S_REDRAW
	 * gets set when the screen isn't worth fixing, and it's simpler to
	 * repaint.  So, don't trust anything that we think we know about it.
	 */
paint:	for (smp = HMAP; smp <= TMAP; ++smp)
		SMAP_FLUSH(smp);
	for (smp = HMAP; smp <= TMAP; ++smp)
		if (svi_line(sp, ep, smp, &y, &SCNO))
			return (1);
	/*
	 * If it's a small screen and we're redrawing, clear the unused lines,
	 * ex may have overwritten them.
	 */
	if (F_ISSET(sp, S_REDRAW)) {
		if (ISSMALLSCREEN(sp))
			for (cnt = sp->t_rows; cnt <= sp->t_maxrows; ++cnt) {
				MOVE(sp, cnt, 0);
				clrtoeol();
			}
		F_CLR(sp, S_REDRAW);
	}

	didpaint = 1;

	/*
	 * 6: Repaint the line numbers.
	 *
	 * If O_NUMBER is set and the S_RENUMBER bit is set, and we didn't
	 * repaint the screen, repaint all of the line numbers, they've
	 * changed.
	 */
number:	if (O_ISSET(sp, O_NUMBER) && F_ISSET(sp, S_RENUMBER) && !didpaint) {
		if (svi_number(sp, ep))
			return (1);
		F_CLR(sp, S_RENUMBER);
	}

	/*
	 * 7: Refresh the screen.
	 *
	 * If the screen was corrupted, refresh it.
	 */
	if (F_ISSET(sp, S_REFRESH)) {
		wrefresh(curscr);
		F_CLR(sp, S_REFRESH);
	}

	if (F_ISSET(sp, S_BELLSCHED))
		svi_bell(sp);
	/*
	 * If the bottom line isn't in use by the colon command, and
	 * we're not in the middle of a map:
	 *
	 *	Display any messages.  Don't test S_UPDATE_MODE.  The
	 *	message printing routine set it to avoid anyone else
	 *	destroying the message we're about to display.
	 *
	 *	If the bottom line isn't in use by anyone, put out the
	 *	standard status line.
	 */
	if (!F_ISSET(SVP(sp), SVI_INFOLINE) && !KEYS_WAITING(sp))
		if (sp->msgq.lh_first != NULL &&
		    !F_ISSET(sp->msgq.lh_first, M_EMPTY))
			svi_msgflush(sp);
		else if (!F_ISSET(sp, S_UPDATE_MODE))
			svi_modeline(sp, ep);

	/* Update saved information. */
	OCNO = CNO;
	OLNO = LNO;

	/* Place the cursor. */
	MOVE(sp, y, SCNO);

	/* Flush it all out. */
	refresh();

	/*
	 * XXX
	 * Recalculate the "most favorite" cursor position.  Vi doesn't know
	 * that we've warped the screen and it's going to have a completely
	 * wrong idea about where the cursor should be.  This is vi's problem,
	 * and fixing it here is a gross violation of layering.
	 */
	if (leftright_warp)
		(void)svi_column(sp, ep, &sp->rcm);

	return (0);
}

/*
 * svi_modeline --
 *	Update the mode line.
 */
static int
svi_modeline(sp, ep)
	SCR *sp;
	EXF *ep;
{
	size_t cols, curlen, endpoint, len, midpoint;
	char *p, buf[20];

	/* Clear the mode line. */
	MOVE(sp, INFOLINE(sp), 0);
	clrtoeol();

	/*
	 * We put down the file name, the ruler, the mode and the dirty flag.
	 * If there's not enough room, there's not enough room, we don't play
	 * any special games.  We try to put the ruler in the middle and the
	 * mode and dirty flag at the end.
	 *
	 * !!!
	 * Leave the last character blank, in case it's a really dumb terminal
	 * with hardware scroll.  Second, don't paint the last character in the
	 * screen, SunOS 4.1.1 and Ultrix 4.2 curses won't let you.
	 */
	cols = sp->cols - 1;

	curlen = 0;
	if (sp->q.cqe_next != (void *)&sp->gp->dq) {
		for (p = sp->frp->name; *p != '\0'; ++p);
		while (--p > sp->frp->name) {
			if (*p == '/') {
				++p;
				break;
			}
			if ((curlen += KEY_LEN(sp, *p)) > cols) {
				curlen -= KEY_LEN(sp, *p);
				++p;
				break;
			}
		}

		MOVE(sp, INFOLINE(sp), 0);
		standout();
		for (; *p != '\0'; ++p)
			ADDCH(*p);
		standend();
	}

	/*
	 * Display the ruler.  If we're not at the midpoint yet, move there.
	 * Otherwise, just add in two extra spaces.
	 *
	 * XXX
	 * Assume that numbers, commas, and spaces only take up a single
	 * column on the screen.
	 */
	if (O_ISSET(sp, O_RULER)) {
		len = snprintf(buf,
		    sizeof(buf), "%lu,%lu", sp->lno, sp->cno + 1);
		midpoint = (cols - ((len + 1) / 2)) / 2;
		if (curlen < midpoint) {
			MOVE(sp, INFOLINE(sp), midpoint);
			ADDSTR(buf);
			curlen += len;
		} else if (curlen + 2 + len < cols) {
			ADDSTR("  ");
			ADDSTR(buf);
			curlen += 2 + len;
		}
	}

	/*
	 * Display the mode and the modified flag, as close to the end of the
	 * line as possible, but guaranteeing at least two spaces between the
	 * ruler and the modified flag.
	 *
	 * XXX
	 * Assume that mode name characters, asterisks, and spaces only take
	 * up a single column on the screen.
	 */
	endpoint = cols;
	if (O_ISSET(sp, O_SHOWDIRTY) && F_ISSET(ep, F_MODIFIED))
		--endpoint;

#define	MODESIZE	9
	if (O_ISSET(sp, O_SHOWMODE))
		endpoint -= MAX_MODE_NAME;

	if (endpoint < curlen + 2)
		return (0);

	MOVE(sp, INFOLINE(sp), endpoint);
	if (O_ISSET(sp, O_SHOWDIRTY) && F_ISSET(ep, F_MODIFIED))
		ADDSTR("*");
	if (O_ISSET(sp, O_SHOWMODE))
		ADDSTR(sp->showmode);
	return (0);
}