MFC:

[dragonfly.git] / contrib / nvi / vi / vs_refresh.c

/*-
 * Copyright (c) 1992, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 * Copyright (c) 1992, 1993, 1994, 1995, 1996
 *      Keith Bostic.  All rights reserved.
 *
 * See the LICENSE file for redistribution information.
 *
 * @(#)vs_refresh.c     10.44 (Berkeley) 10/13/96
 * $FreeBSD: src/contrib/nvi/vi/vs_refresh.c,v 1.2.6.1 2001/07/31 00:03:41 dd Exp $
 * $DragonFly: src/contrib/nvi/vi/vs_refresh.c,v 1.2 2003/06/17 04:24:04 dillon Exp $
 */

#include "config.h"

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

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

#include "../common/common.h"
#include "vi.h"

#define UPDATE_CURSOR   0x01                    /* Update the cursor. */
#define UPDATE_SCREEN   0x02                    /* Flush to screen. */

static void     vs_modeline __P((SCR *));
static int      vs_paint __P((SCR *, u_int));

/*
 * v_repaint --
 *      Repaint selected lines from the screen.
 *
 * PUBLIC: int vs_repaint __P((SCR *, EVENT *));
 */
int
vs_repaint(sp, evp)
        SCR *sp;
        EVENT *evp;
{
        SMAP *smp;

        for (; evp->e_flno <= evp->e_tlno; ++evp->e_flno) {
                smp = HMAP + evp->e_flno - 1;
                SMAP_FLUSH(smp);
                if (vs_line(sp, smp, NULL, NULL))
                        return (1);
        }
        return (0);
}

/*
 * vs_refresh --
 *      Refresh all screens.
 *
 * PUBLIC: int vs_refresh __P((SCR *, int));
 */
int
vs_refresh(sp, forcepaint)
        SCR *sp;
        int forcepaint;
{
        GS *gp;
        SCR *tsp;
        int need_refresh;
        u_int priv_paint, pub_paint;

        gp = sp->gp;

        /*
         * 1: Refresh the screen.
         *
         * If SC_SCR_REDRAW is set in the current screen, repaint everything
         * that we can find, including status lines.
         */
        if (F_ISSET(sp, SC_SCR_REDRAW))
                for (tsp = gp->dq.cqh_first;
                    tsp != (void *)&gp->dq; tsp = tsp->q.cqe_next)
                        if (tsp != sp)
                                F_SET(tsp, SC_SCR_REDRAW | SC_STATUS);

        /*
         * 2: 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 that aren't exiting that
         * have paint or dirty bits set.  Always update their screens, we
         * are not likely to get another chance.  Finally, if we refresh any
         * screens other than the current one, the cursor will be trashed.
         */
        pub_paint = SC_SCR_REFORMAT | SC_SCR_REDRAW;
        priv_paint = VIP_CUR_INVALID | VIP_N_REFRESH;
        if (O_ISSET(sp, O_NUMBER))
                priv_paint |= VIP_N_RENUMBER;
        for (tsp = gp->dq.cqh_first;
            tsp != (void *)&gp->dq; tsp = tsp->q.cqe_next)
                if (tsp != sp && !F_ISSET(tsp, SC_EXIT | SC_EXIT_FORCE) &&
                    (F_ISSET(tsp, pub_paint) ||
                    F_ISSET(VIP(tsp), priv_paint))) {
                        (void)vs_paint(tsp,
                            (F_ISSET(VIP(tsp), VIP_CUR_INVALID) ?
                            UPDATE_CURSOR : 0) | UPDATE_SCREEN);
                        F_SET(VIP(sp), VIP_CUR_INVALID);
                }

        /*
         * 3: Refresh the current screen.
         *
         * Always refresh the current screen, it may be a cursor movement.
         * Also, always do it last -- that way, SC_SCR_REDRAW can be set
         * in the current screen only, and the screen won't flash.
         */
        if (vs_paint(sp, UPDATE_CURSOR | (!forcepaint &&
            F_ISSET(sp, SC_SCR_VI) && KEYS_WAITING(sp) ? 0 : UPDATE_SCREEN)))
                return (1);

        /*
         * 4: Paint any missing status lines.
         *
         * XXX
         * This is fairly evil.  Status lines are written using the vi message
         * mechanism, since we have no idea how long they are.  Since we may be
         * painting screens other than the current one, we don't want to make
         * the user wait.  We depend heavily on there not being any other lines
         * currently waiting to be displayed and the message truncation code in
         * the msgq_status routine working.
         *
         * And, finally, if we updated any status lines, make sure the cursor
         * gets back to where it belongs.
         */
        for (need_refresh = 0, tsp = gp->dq.cqh_first;
            tsp != (void *)&gp->dq; tsp = tsp->q.cqe_next)
                if (F_ISSET(tsp, SC_STATUS)) {
                        need_refresh = 1;
                        vs_resolve(tsp, sp, 0);
                }
        if (need_refresh)
                (void)gp->scr_refresh(sp, 0);

        /*
         * A side-effect of refreshing the screen is that it's now ready
         * for everything else, i.e. messages.
         */
        F_SET(sp, SC_SCR_VI);
        return (0);
}

/*
 * vs_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.
 */
static int
vs_paint(sp, flags)
        SCR *sp;
        u_int flags;
{
        GS *gp;
        SMAP *smp, tmp;
        VI_PRIVATE *vip;
        recno_t lastline, lcnt;
        size_t cwtotal, cnt, len, notused, off, y;
        int ch, didpaint, isempty, leftright_warp;
        char *p;

#define  LNO    sp->lno                 /* Current file line. */
#define OLNO    vip->olno               /* Remembered file line. */
#define  CNO    sp->cno                 /* Current file column. */
#define OCNO    vip->ocno               /* Remembered file column. */
#define SCNO    vip->sc_col             /* Current screen column. */

        gp = sp->gp;
        vip = VIP(sp);
        didpaint = leftright_warp = 0;

        /*
         * 5: 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, SC_SCR_REFORMAT)) {
                /* Invalidate the line size cache. */
                VI_SCR_CFLUSH(vip);

                /* Toss vs_line() cached information. */
                if (F_ISSET(sp, SC_SCR_TOP)) {
                        if (vs_sm_fill(sp, LNO, P_TOP))
                                return (1);
                }
                else if (F_ISSET(sp, SC_SCR_CENTER)) {
                        if (vs_sm_fill(sp, LNO, P_MIDDLE))
                                return (1);
                } else
                        if (vs_sm_fill(sp, OOBLNO, P_TOP))
                                return (1);
                F_SET(sp, SC_SCR_REDRAW);
        }

        /*
         * 6: Line movement.
         *
         * Line changes can cause the top line to change as well.  As
         * before, if the movement is large, the screen is repainted.
         *
         * 6a: 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 (IS_SMALL(sp))
                if (LNO < HMAP->lno) {
                        lcnt = vs_sm_nlines(sp, HMAP, LNO, sp->t_maxrows);
                        if (lcnt <= HALFSCREEN(sp))
                                for (; lcnt && sp->t_rows != sp->t_maxrows;
                                     --lcnt, ++sp->t_rows) {
                                        ++TMAP;
                                        if (vs_sm_1down(sp))
                                                return (1);
                                }
                        else
                                goto small_fill;
                } else if (LNO > TMAP->lno) {
                        lcnt = vs_sm_nlines(sp, TMAP, LNO, sp->t_maxrows);
                        if (lcnt <= HALFSCREEN(sp))
                                for (; lcnt && sp->t_rows != sp->t_maxrows;
                                     --lcnt, ++sp->t_rows) {
                                        if (vs_sm_next(sp, TMAP, TMAP + 1))
                                                return (1);
                                        ++TMAP;
                                        if (vs_line(sp, TMAP, NULL, NULL))
                                                return (1);
                                }
                        else {
small_fill:                     (void)gp->scr_move(sp, LASTLINE(sp), 0);
                                (void)gp->scr_clrtoeol(sp);
                                for (; sp->t_rows > sp->t_minrows;
                                    --sp->t_rows, --TMAP) {
                                        (void)gp->scr_move(sp, TMAP - HMAP, 0);
                                        (void)gp->scr_clrtoeol(sp);
                                }
                                if (vs_sm_fill(sp, LNO, P_FILL))
                                        return (1);
                                F_SET(sp, SC_SCR_REDRAW);
                                goto adjust;
                        }
                }

        /*
         * 6b: Line down, or current screen.
         */
        if (LNO >= HMAP->lno) {
                /* Current screen. */
                if (LNO <= TMAP->lno)
                        goto adjust;
                if (F_ISSET(sp, SC_SCR_TOP))
                        goto top;
                if (F_ISSET(sp, SC_SCR_CENTER))
                        goto middle;

                /*
                 * If less than half a screen above the line, scroll down
                 * until the line is on the screen.
                 */
                lcnt = vs_sm_nlines(sp, TMAP, LNO, HALFTEXT(sp));
                if (lcnt < HALFTEXT(sp)) {
                        while (lcnt--)
                                if (vs_sm_1up(sp))
                                        return (1);
                        goto adjust;
                }
                goto bottom;
        }

        /*
         * 6c: If not on the current screen, may request center or top.
         */
        if (F_ISSET(sp, SC_SCR_TOP))
                goto top;
        if (F_ISSET(sp, SC_SCR_CENTER))
                goto middle;

        /*
         * 6d: Line up.
         */
        lcnt = vs_sm_nlines(sp, 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 (db_exist(sp, HMAP->lno)) {
                        while (lcnt--)
                                if (vs_sm_1down(sp))
                                        return (1);
                        goto adjust;
                }

                /*
                 * If less than a half screen from the bottom of the file,
                 * put the last line of the file on the bottom of the screen.
                 */
bottom:         if (db_last(sp, &lastline))
                        return (1);
                tmp.lno = LNO;
                tmp.coff = HMAP->coff;
                tmp.soff = 1;
                lcnt = vs_sm_nlines(sp, &tmp, lastline, sp->t_rows);
                if (lcnt < HALFTEXT(sp)) {
                        if (vs_sm_fill(sp, lastline, P_BOTTOM))
                                return (1);
                        F_SET(sp, SC_SCR_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.coff = HMAP->coff;
        tmp.soff = 1;
        lcnt = vs_sm_nlines(sp, &tmp, LNO, HALFTEXT(sp));
        if (lcnt < HALFTEXT(sp)) {
                if (vs_sm_fill(sp, 1, P_TOP))
                        return (1);
        } else
middle:         if (vs_sm_fill(sp, LNO, P_MIDDLE))
                        return (1);
        if (0) {
top:            if (vs_sm_fill(sp, LNO, P_TOP))
                        return (1);
        }
        F_SET(sp, SC_SCR_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 = vs_screens(sp, LNO, &CNO);
                if (LNO == HMAP->lno && cnt < HMAP->soff)
                        if ((HMAP->soff - cnt) > HALFTEXT(sp)) {
                                HMAP->soff = cnt;
                                vs_sm_fill(sp, OOBLNO, P_TOP);
                                F_SET(sp, SC_SCR_REDRAW);
                        } else
                                while (cnt < HMAP->soff)
                                        if (vs_sm_1down(sp))
                                                return (1);
                if (LNO == TMAP->lno && cnt > TMAP->soff)
                        if ((cnt - TMAP->soff) > HALFTEXT(sp)) {
                                TMAP->soff = cnt;
                                vs_sm_fill(sp, OOBLNO, P_BOTTOM);
                                F_SET(sp, SC_SCR_REDRAW);
                        } else
                                while (cnt > TMAP->soff)
                                        if (vs_sm_1up(sp))
                                                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, SC_SCR_REDRAW)) {
                if (O_ISSET(sp, O_LEFTRIGHT))
                        goto slow;
                goto paint;
        }

        /*
         * 7: Cursor movements (current screen only).
         */
        if (!LF_ISSET(UPDATE_CURSOR))
                goto number;

        /*
         * 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, reread it..
         */
        if (F_ISSET(vip, VIP_CUR_INVALID) || LNO != OLNO)
                goto slow;

        /* Otherwise, if nothing's changed, ignore the cursor. */
        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 (db_eget(sp, LNO, &p, &len, &isempty)) {
                if (isempty)
                        goto slow;
                return (1);
        }

#ifdef DEBUG
        /* Sanity checking. */
        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) {
                /*
                 * 7a: 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 slow;

                /*
                 * 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.
                 */
                if (SCNO < cwtotal)
                        goto slow;
                SCNO -= cwtotal;
        } else {
                /*
                 * 7b: 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 6a. */
                if (SCNO >= SCREEN_COLS(sp))
                        goto slow;
        }

        /*
         * 7c: Fast cursor update.
         *
         * We have the current column, retrieve the current row.
         */
fast:   (void)gp->scr_cursor(sp, &y, &notused);
        goto done_cursor;

        /*
         * 7d: Slow cursor update.
         *
         * Walk through the map and find the current line.
         */
slow:   for (smp = HMAP; smp->lno != LNO; ++smp);

        /*
         * 7e: Leftright scrolling adjustment.
         *
         * If doing left-right scrolling and the cursor movement has changed
         * the displayed screen, scroll the screen left or right, unless we're
         * updating the info line in which case we just scroll that one line.
         * We adjust the offset up or down until we have a window that covers
         * the current column, making sure that we adjust differently for the
         * first screen as compared to subsequent ones.
         */
        if (O_ISSET(sp, O_LEFTRIGHT)) {
                /*
                 * Get the screen column for this character, and correct
                 * for the number option offset.
                 */
                cnt = vs_columns(sp, NULL, LNO, &CNO, NULL);
                if (O_ISSET(sp, O_NUMBER) && cnt >= O_NUMBER_LENGTH)
                        cnt -= O_NUMBER_LENGTH;

                /* Adjust the window towards the beginning of the line. */
                off = smp->coff;
                if (off >= cnt) {
                        do {
                                if (off >= O_VAL(sp, O_SIDESCROLL))
                                        off -= O_VAL(sp, O_SIDESCROLL);
                                else {
                                        off = 0;
                                        break;
                                }
                        } while (off >= cnt);
                        goto shifted;
                }

                /* Adjust the window towards the end of the line. */
                if (off == 0 && off + SCREEN_COLS(sp) < cnt ||
                    off != 0 && off + sp->cols < cnt) {
                        do {
                                off += O_VAL(sp, O_SIDESCROLL);
                        } while (off + sp->cols < cnt);

shifted:                /* Fill in screen map with the new offset. */
                        if (F_ISSET(sp, SC_TINPUT_INFO))
                                smp->coff = off;
                        else {
                                for (smp = HMAP; smp <= TMAP; ++smp)
                                        smp->coff = off;
                                leftright_warp = 1;
                        }
                        goto paint;
                }

                /*
                 * We may have jumped here to adjust a leftright screen because
                 * redraw was set.  If so, we have to paint the entire screen.
                 */
                if (F_ISSET(sp, SC_SCR_REDRAW))
                        goto paint;
        }

        /*
         * Update the screen lines for this particular file line until we
         * have a new screen cursor position.
         */
        for (y = -1,
            vip->sc_smap = NULL; smp <= TMAP && smp->lno == LNO; ++smp) {
                if (vs_line(sp, smp, &y, &SCNO))
                        return (1);
                if (y != -1) {
                        vip->sc_smap = smp;
                        break;
                }
        }
        goto done_cursor;

        /*
         * 8: Repaint the entire screen.
         *
         * Lost big, do what you have to do.  We flush the cache, since
         * SC_SCR_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 (y = -1, vip->sc_smap = NULL, smp = HMAP; smp <= TMAP; ++smp) {
                if (vs_line(sp, smp, &y, &SCNO))
                        return (1);
                if (y != -1 && vip->sc_smap == NULL)
                        vip->sc_smap = smp;
        }
        /*
         * If it's a small screen and we're redrawing, clear the unused lines,
         * ex may have overwritten them.
         */
        if (F_ISSET(sp, SC_SCR_REDRAW) && IS_SMALL(sp))
                for (cnt = sp->t_rows; cnt <= sp->t_maxrows; ++cnt) {
                        (void)gp->scr_move(sp, cnt, 0);
                        (void)gp->scr_clrtoeol(sp);
                }

        didpaint = 1;

done_cursor:
        /*
         * Sanity checking.  When the repainting code messes up, the usual
         * result is we don't repaint the cursor and so sc_smap will be
         * NULL.  If we're debugging, die, otherwise restart from scratch.
         */
#ifdef DEBUG
        if (vip->sc_smap == NULL)
                abort();
#else
        if (vip->sc_smap == NULL) {
                F_SET(sp, SC_SCR_REFORMAT);
                return (vs_paint(sp, flags));
        }
#endif

        /*
         * 9: Set the remembered cursor values.
         */
        OCNO = CNO;
        OLNO = LNO;

        /*
         * 10: Repaint the line numbers.
         *
         * If O_NUMBER is set and the VIP_N_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(vip, VIP_N_RENUMBER) && !didpaint && vs_number(sp))
                return (1);

        /*
         * 11: Update the mode line, position the cursor, and flush changes.
         *
         * If we warped the screen, we have to refresh everything.
         */
        if (leftright_warp)
                LF_SET(UPDATE_CURSOR | UPDATE_SCREEN);

        if (LF_ISSET(UPDATE_SCREEN) && !IS_ONELINE(sp) &&
            !F_ISSET(vip, VIP_S_MODELINE) && !F_ISSET(sp, SC_TINPUT_INFO))
                vs_modeline(sp);

        if (LF_ISSET(UPDATE_CURSOR)) {
                (void)gp->scr_move(sp, y, SCNO);

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

        if (LF_ISSET(UPDATE_SCREEN))
                (void)gp->scr_refresh(sp, F_ISSET(vip, VIP_N_EX_PAINT));

        /* 12: Clear the flags that are handled by this routine. */
        F_CLR(sp, SC_SCR_CENTER | SC_SCR_REDRAW | SC_SCR_REFORMAT | SC_SCR_TOP);
        F_CLR(vip, VIP_CUR_INVALID |
            VIP_N_EX_PAINT | VIP_N_REFRESH | VIP_N_RENUMBER | VIP_S_MODELINE);

        return (0);

#undef   LNO
#undef  OLNO
#undef   CNO
#undef  OCNO
#undef  SCNO
}

/*
 * vs_modeline --
 *      Update the mode line.
 */
static void
vs_modeline(sp)
        SCR *sp;
{
        static char * const modes[] = {
                "215|Append",                   /* SM_APPEND */
                "216|Change",                   /* SM_CHANGE */
                "217|Command",                  /* SM_COMMAND */
                "218|Insert",                   /* SM_INSERT */
                "219|Replace",                  /* SM_REPLACE */
        };
        GS *gp;
        size_t cols, curcol, curlen, endpoint, len, midpoint;
        const char *t;
        int ellipsis;
        char *p, buf[20];

        gp = sp->gp;

        /*
         * 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.
         *
         * Move to the last line on the screen.
         */
        (void)gp->scr_move(sp, LASTLINE(sp), 0);

        /* If more than one screen in the display, show the file name. */
        curlen = 0;
        if (IS_SPLIT(sp)) {
                for (p = sp->frp->name; *p != '\0'; ++p);
                for (ellipsis = 0, cols = sp->cols / 2; --p > sp->frp->name;) {
                        if (*p == '/') {
                                ++p;
                                break;
                        }
                        if ((curlen += KEY_LEN(sp, *p)) > cols) {
                                ellipsis = 3;
                                curlen +=
                                    KEY_LEN(sp, '.') * 3 + KEY_LEN(sp, ' ');
                                while (curlen > cols) {
                                        ++p;
                                        curlen -= KEY_LEN(sp, *p);
                                }
                                break;
                        }
                }
                if (ellipsis) {
                        while (ellipsis--)
                                (void)gp->scr_addstr(sp,
                                    KEY_NAME(sp, '.'), KEY_LEN(sp, '.'));
                        (void)gp->scr_addstr(sp,
                            KEY_NAME(sp, ' '), KEY_LEN(sp, ' '));
                }
                for (; *p != '\0'; ++p)
                        (void)gp->scr_addstr(sp,
                            KEY_NAME(sp, *p), KEY_LEN(sp, *p));
        }

        /* Clear the rest of the line. */
        (void)gp->scr_clrtoeol(sp);

        /*
         * Display the ruler.  If we're not at the midpoint yet, move there.
         * Otherwise, add in two extra spaces.
         *
         * Adjust the current column for the fact that the editor uses it as
         * a zero-based number.
         *
         * XXX
         * Assume that numbers, commas, and spaces only take up a single
         * column on the screen.
         */
        cols = sp->cols - 1;
        if (O_ISSET(sp, O_RULER)) {
                vs_column(sp, &curcol);
                len = snprintf(buf, sizeof(buf), "%lu,%lu",
                    (u_long)sp->lno, (u_long)(curcol + 1));

                midpoint = (cols - ((len + 1) / 2)) / 2;
                if (curlen < midpoint) {
                        (void)gp->scr_move(sp, LASTLINE(sp), midpoint);
                        curlen += len;
                } else if (curlen + 2 + len < cols) {
                        (void)gp->scr_addstr(sp, "  ", 2);
                        curlen += 2 + len;
                }
                (void)gp->scr_addstr(sp, buf, 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.
         */
#define MODESIZE        9
        endpoint = cols;
        if (O_ISSET(sp, O_SHOWMODE)) {
                if (F_ISSET(sp->ep, F_MODIFIED))
                        --endpoint;
                t = msg_cat(sp, modes[sp->showmode], &len);
                endpoint -= len;
        }

        if (endpoint > curlen + 2) {
                (void)gp->scr_move(sp, LASTLINE(sp), endpoint);
                if (O_ISSET(sp, O_SHOWMODE)) {
                        if (F_ISSET(sp->ep, F_MODIFIED))
                                (void)gp->scr_addstr(sp,
                                    KEY_NAME(sp, '*'), KEY_LEN(sp, '*'));
                        (void)gp->scr_addstr(sp, t, len);
                }
        }
}