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Add a global-wd-mode command, which toggles between the current
behavior (every buffer maintains its own cwd) and the old behavior of
one global working directory. This makes it slightly easier to hack
on things like kernel code, where compilation, etc, are initiated from
a different directory than you are working in.
While here, fix setting/handling of global wd.

/*	$OpenBSD: display.c,v 1.35 2007/05/28 17:52:17 kjell Exp $	*/

/* This file is in the public domain. */

/*
 * The functions in this file handle redisplay. The
 * redisplay system knows almost nothing about the editing
 * process; the editing functions do, however, set some
 * hints to eliminate a lot of the grinding. There is more
 * that can be done; the "vtputc" interface is a real
 * pig.
 */
#include "def.h"
#include "kbd.h"

#include <ctype.h>

/*
 * You can change these back to the types
 * implied by the name if you get tight for space. If you
 * make both of them "int" you get better code on the VAX.
 * They do nothing if this is not Gosling redisplay, except
 * for change the size of a structure that isn't used.
 * A bit of a cheat.
 */
#define	XCHAR	int
#define	XSHORT	int

#ifdef	STANDOUT_GLITCH
#include <term.h>
#endif

/*
 * A video structure always holds
 * an array of characters whose length is equal to
 * the longest line possible. v_text is allocated
 * dynamically to fit the screen width.
 */
struct video {
	short	v_hash;		/* Hash code, for compares.	 */
	short	v_flag;		/* Flag word.			 */
	short	v_color;	/* Color of the line.		 */
	XSHORT	v_cost;		/* Cost of display.		 */
	char	*v_text;	/* The actual characters.	 */
};

#define VFCHG	0x0001			/* Changed.			 */
#define VFHBAD	0x0002			/* Hash and cost are bad.	 */
#define VFEXT	0x0004			/* extended line (beond ncol)	 */

/*
 * SCORE structures hold the optimal
 * trace trajectory, and the cost of redisplay, when
 * the dynamic programming redisplay code is used.
 * If no fancy redisplay, this isn't used. The trace index
 * fields can be "char", and the cost a "short", but
 * this makes the code worse on the VAX.
 */
struct score {
	XCHAR	s_itrace;	/* "i" index for track back.	 */
	XCHAR	s_jtrace;	/* "j" index for trace back.	 */
	XSHORT	s_cost;		/* Display cost.		 */
};

void	vtmove(int, int);
void	vtputc(int);
void	vtpute(int);
int	vtputs(const char *);
void	vteeol(void);
void	updext(int, int);
void	modeline(struct mgwin *);
void	setscores(int, int);
void	traceback(int, int, int, int);
void	ucopy(struct video *, struct video *);
void	uline(int, struct video *, struct video *);
void	hash(struct video *);


int	sgarbf = TRUE;		/* TRUE if screen is garbage.	 */
int	vtrow = HUGE;		/* Virtual cursor row.		 */
int	vtcol = HUGE;		/* Virtual cursor column.	 */
int	tthue = CNONE;		/* Current color.		 */
int	ttrow = HUGE;		/* Physical cursor row.		 */
int	ttcol = HUGE;		/* Physical cursor column.	 */
int	tttop = HUGE;		/* Top of scroll region.	 */
int	ttbot = HUGE;		/* Bottom of scroll region.	 */
int	lbound = 0;		/* leftmost bound of the current */
				/* line being displayed		 */

struct video	**vscreen;		/* Edge vector, virtual.	 */
struct video	**pscreen;		/* Edge vector, physical.	 */
struct video	 *video;		/* Actual screen data.		 */
struct video	  blanks;		/* Blank line image.		 */

/*
 * This matrix is written as an array because
 * we do funny things in the "setscores" routine, which
 * is very compute intensive, to make the subscripts go away.
 * It would be "SCORE	score[NROW][NROW]" in old speak.
 * Look at "setscores" to understand what is up.
 */
struct score *score;			/* [NROW * NROW] */

#ifndef LINENOMODE
#define LINENOMODE TRUE
#endif /* !LINENOMODE */
static int	 linenos = LINENOMODE;

/* Is macro recording enabled? */
extern int macrodef;
/* Is working directory global? */
extern int globalwd;

/*
 * Since we don't have variables (we probably should) these are command
 * processors for changing the values of mode flags.
 */
/* ARGSUSED */
int
linenotoggle(int f, int n)
{
	if (f & FFARG)
		linenos = n > 0;
	else
		linenos = !linenos;

	sgarbf = TRUE;

	return (TRUE);
}

/*
 * Reinit the display data structures, this is called when the terminal
 * size changes.
 */
int
vtresize(int force, int newrow, int newcol)
{
	int	 i;
	int	 rowchanged, colchanged;
	static	 int first_run = 1;
	struct video	*vp;

	if (newrow < 1 || newcol < 1)
		return (FALSE);

	rowchanged = (newrow != nrow);
	colchanged = (newcol != ncol);

#define TRYREALLOC(a, n) do {					\
		void *tmp;					\
		if ((tmp = realloc((a), (n))) == NULL) {	\
			panic("out of memory in display code");	\
		}						\
		(a) = tmp;					\
	} while (0)

	/* No update needed */
	if (!first_run && !force && !rowchanged && !colchanged)
		return (TRUE);

	if (first_run)
		memset(&blanks, 0, sizeof(blanks));

	if (rowchanged || first_run) {
		int vidstart;

		/*
		 * This is not pretty.
		 */
		if (nrow == 0)
			vidstart = 0;
		else
			vidstart = 2 * (nrow - 1);

		/*
		 * We're shrinking, free some internal data.
		 */
		if (newrow < nrow) {
			for (i = 2 * (newrow - 1); i < 2 * (nrow - 1); i++) {
				free(video[i].v_text);
				video[i].v_text = NULL;
			}
		}

		TRYREALLOC(score, newrow * newrow * sizeof(struct score));
		TRYREALLOC(vscreen, (newrow - 1) * sizeof(struct video *));
		TRYREALLOC(pscreen, (newrow - 1) * sizeof(struct video *));
		TRYREALLOC(video, (2 * (newrow - 1)) * sizeof(struct video));

		/*
		 * Zero-out the entries we just allocated.
		 */
		for (i = vidstart; i < 2 * (newrow - 1); i++)
			memset(&video[i], 0, sizeof(struct video));

		/*
		 * Reinitialize vscreen and pscreen arrays completely.
		 */
		vp = &video[0];
		for (i = 0; i < newrow - 1; ++i) {
			vscreen[i] = vp;
			++vp;
			pscreen[i] = vp;
			++vp;
		}
	}
	if (rowchanged || colchanged || first_run) {
		for (i = 0; i < 2 * (newrow - 1); i++)
			TRYREALLOC(video[i].v_text, newcol * sizeof(char));
		TRYREALLOC(blanks.v_text, newcol * sizeof(char));
	}

	nrow = newrow;
	ncol = newcol;

	if (ttrow > nrow)
		ttrow = nrow;
	if (ttcol > ncol)
		ttcol = ncol;

	first_run = 0;
	return (TRUE);
}

#undef TRYREALLOC

/*
 * Initialize the data structures used
 * by the display code. The edge vectors used
 * to access the screens are set up. The operating
 * system's terminal I/O channel is set up. Fill the
 * "blanks" array with ASCII blanks. The rest is done
 * at compile time. The original window is marked
 * as needing full update, and the physical screen
 * is marked as garbage, so all the right stuff happens
 * on the first call to redisplay.
 */
void
vtinit(void)
{
	int	i;

	ttopen();
	ttinit();

	/*
	 * ttinit called ttresize(), which called vtresize(), so our data
	 * structures are setup correctly.
	 */

	blanks.v_color = CTEXT;
	for (i = 0; i < ncol; ++i)
		blanks.v_text[i] = ' ';
}

/*
 * Tidy up the virtual display system
 * in anticipation of a return back to the host
 * operating system. Right now all we do is position
 * the cursor to the last line, erase the line, and
 * close the terminal channel.
 */
void
vttidy(void)
{
	ttcolor(CTEXT);
	ttnowindow();		/* No scroll window.	 */
	ttmove(nrow - 1, 0);	/* Echo line.		 */
	tteeol();
	tttidy();
	ttflush();
	ttclose();
}

/*
 * Move the virtual cursor to an origin
 * 0 spot on the virtual display screen. I could
 * store the column as a character pointer to the spot
 * on the line, which would make "vtputc" a little bit
 * more efficient. No checking for errors.
 */
void
vtmove(int row, int col)
{
	vtrow = row;
	vtcol = col;
}

/*
 * Write a character to the virtual display,
 * dealing with long lines and the display of unprintable
 * things like control characters. Also expand tabs every 8
 * columns. This code only puts printing characters into
 * the virtual display image. Special care must be taken when
 * expanding tabs. On a screen whose width is not a multiple
 * of 8, it is possible for the virtual cursor to hit the
 * right margin before the next tab stop is reached. This
 * makes the tab code loop if you are not careful.
 * Three guesses how we found this.
 */
void
vtputc(int c)
{
	struct video	*vp;

	c &= 0xff;

	vp = vscreen[vtrow];
	if (vtcol >= ncol)
		vp->v_text[ncol - 1] = '$';
	else if (c == '\t'
#ifdef	NOTAB
	    && !(curbp->b_flag & BFNOTAB)
#endif
	    ) {
		do {
			vtputc(' ');
		} while (vtcol < ncol && (vtcol & 0x07) != 0);
	} else if (ISCTRL(c)) {
		vtputc('^');
		vtputc(CCHR(c));
	} else if (isprint(c))
		vp->v_text[vtcol++] = c;
	else {
		char bf[5];

		snprintf(bf, sizeof(bf), "\\%o", c);
		vtputs(bf);
	}
}

/*
 * Put a character to the virtual screen in an extended line.  If we are not
 * yet on left edge, don't print it yet.  Check for overflow on the right
 * margin.
 */
void
vtpute(int c)
{
	struct video *vp;

	c &= 0xff;

	vp = vscreen[vtrow];
	if (vtcol >= ncol)
		vp->v_text[ncol - 1] = '$';
	else if (c == '\t'
#ifdef	NOTAB
	    && !(curbp->b_flag & BFNOTAB)
#endif
	    ) {
		do {
			vtpute(' ');
		} while (((vtcol + lbound) & 0x07) != 0 && vtcol < ncol);
	} else if (ISCTRL(c) != FALSE) {
		vtpute('^');
		vtpute(CCHR(c));
	} else {
		if (vtcol >= 0)
			vp->v_text[vtcol] = c;
		++vtcol;
	}
}

/*
 * Erase from the end of the software cursor to the end of the line on which
 * the software cursor is located. The display routines will decide if a
 * hardware erase to end of line command should be used to display this.
 */
void
vteeol(void)
{
	struct video *vp;

	vp = vscreen[vtrow];
	while (vtcol < ncol)
		vp->v_text[vtcol++] = ' ';
}

/*
 * Make sure that the display is
 * right. This is a three part process. First,
 * scan through all of the windows looking for dirty
 * ones. Check the framing, and refresh the screen.
 * Second, make sure that "currow" and "curcol" are
 * correct for the current window. Third, make the
 * virtual and physical screens the same.
 */
void
update(void)
{
	struct line	*lp;
	struct mgwin	*wp;
	struct video	*vp1;
	struct video	*vp2;
	int	 c, i, j;
	int	 hflag;
	int	 currow, curcol;
	int	 offs, size;

	if (charswaiting())
		return;
	if (sgarbf) {		/* must update everything */
		wp = wheadp;
		while (wp != NULL) {
			wp->w_flag |= WFMODE | WFFULL;
			wp = wp->w_wndp;
		}
	}
	if (linenos) {
		wp = wheadp;
		while (wp != NULL) {
			wp->w_flag |= WFMODE;
			wp = wp->w_wndp;
		}
	}
	hflag = FALSE;			/* Not hard. */
	for (wp = wheadp; wp != NULL; wp = wp->w_wndp) {
		/*
		 * Nothing to be done.
		 */
		if (wp->w_flag == 0)
			continue;

		if ((wp->w_flag & WFFRAME) == 0) {
			lp = wp->w_linep;
			for (i = 0; i < wp->w_ntrows; ++i) {
				if (lp == wp->w_dotp)
					goto out;
				if (lp == wp->w_bufp->b_headp)
					break;
				lp = lforw(lp);
			}
		}
		/*
		 * Put the middle-line in place.
		 */
		i = wp->w_frame;
		if (i > 0) {
			--i;
			if (i >= wp->w_ntrows)
				i = wp->w_ntrows - 1;
		} else if (i < 0) {
			i += wp->w_ntrows;
			if (i < 0)
				i = 0;
		} else
			i = wp->w_ntrows / 2; /* current center, no change */

		/*
		 * Find the line.
		 */
		lp = wp->w_dotp;
		while (i != 0 && lback(lp) != wp->w_bufp->b_headp) {
			--i;
			lp = lback(lp);
		}
		wp->w_linep = lp;
		wp->w_flag |= WFFULL;	/* Force full.		 */
	out:
		lp = wp->w_linep;	/* Try reduced update.	 */
		i = wp->w_toprow;
		if ((wp->w_flag & ~WFMODE) == WFEDIT) {
			while (lp != wp->w_dotp) {
				++i;
				lp = lforw(lp);
			}
			vscreen[i]->v_color = CTEXT;
			vscreen[i]->v_flag |= (VFCHG | VFHBAD);
			vtmove(i, 0);
			for (j = 0; j < llength(lp); ++j)
				vtputc(lgetc(lp, j));
			vteeol();
		} else if ((wp->w_flag & (WFEDIT | WFFULL)) != 0) {
			hflag = TRUE;
			while (i < wp->w_toprow + wp->w_ntrows) {
				vscreen[i]->v_color = CTEXT;
				vscreen[i]->v_flag |= (VFCHG | VFHBAD);
				vtmove(i, 0);
				if (lp != wp->w_bufp->b_headp) {
					for (j = 0; j < llength(lp); ++j)
						vtputc(lgetc(lp, j));
					lp = lforw(lp);
				}
				vteeol();
				++i;
			}
		}
		if ((wp->w_flag & WFMODE) != 0)
			modeline(wp);
		wp->w_flag = 0;
		wp->w_frame = 0;
	}
	lp = curwp->w_linep;	/* Cursor location. */
	currow = curwp->w_toprow;
	while (lp != curwp->w_dotp) {
		++currow;
		lp = lforw(lp);
	}
	curcol = 0;
	i = 0;
	while (i < curwp->w_doto) {
		c = lgetc(lp, i++);
		if (c == '\t'
#ifdef	NOTAB
		    && !(curbp->b_flag & BFNOTAB)
#endif
			) {
			curcol |= 0x07;
			curcol++;
		} else if (ISCTRL(c) != FALSE)
			curcol += 2;
		else if (isprint(c))
			curcol++;
		else {
			char bf[5];

			snprintf(bf, sizeof(bf), "\\%o", c);
			curcol += strlen(bf);
		}
	}
	if (curcol >= ncol - 1) {	/* extended line. */
		/* flag we are extended and changed */
		vscreen[currow]->v_flag |= VFEXT | VFCHG;
		updext(currow, curcol);	/* and output extended line */
	} else
		lbound = 0;	/* not extended line */

	/*
	 * Make sure no lines need to be de-extended because the cursor is no
	 * longer on them.
	 */
	wp = wheadp;
	while (wp != NULL) {
		lp = wp->w_linep;
		i = wp->w_toprow;
		while (i < wp->w_toprow + wp->w_ntrows) {
			if (vscreen[i]->v_flag & VFEXT) {
				/* always flag extended lines as changed */
				vscreen[i]->v_flag |= VFCHG;
				if ((wp != curwp) || (lp != wp->w_dotp) ||
				    (curcol < ncol - 1)) {
					vtmove(i, 0);
					for (j = 0; j < llength(lp); ++j)
						vtputc(lgetc(lp, j));
					vteeol();
					/* this line no longer is extended */
					vscreen[i]->v_flag &= ~VFEXT;
				}
			}
			lp = lforw(lp);
			++i;
		}
		/* if garbaged then fix up mode lines */
		if (sgarbf != FALSE)
			vscreen[i]->v_flag |= VFCHG;
		/* and onward to the next window */
		wp = wp->w_wndp;
	}

	if (sgarbf != FALSE) {	/* Screen is garbage.	 */
		sgarbf = FALSE;	/* Erase-page clears.	 */
		epresf = FALSE;	/* The message area.	 */
		tttop = HUGE;	/* Forget where you set. */
		ttbot = HUGE;	/* scroll region.	 */
		tthue = CNONE;	/* Color unknown.	 */
		ttmove(0, 0);
		tteeop();
		for (i = 0; i < nrow - 1; ++i) {
			uline(i, vscreen[i], &blanks);
			ucopy(vscreen[i], pscreen[i]);
		}
		ttmove(currow, curcol - lbound);
		ttflush();
		return;
	}
	if (hflag != FALSE) {			/* Hard update?		*/
		for (i = 0; i < nrow - 1; ++i) {/* Compute hash data.	*/
			hash(vscreen[i]);
			hash(pscreen[i]);
		}
		offs = 0;			/* Get top match.	*/
		while (offs != nrow - 1) {
			vp1 = vscreen[offs];
			vp2 = pscreen[offs];
			if (vp1->v_color != vp2->v_color
			    || vp1->v_hash != vp2->v_hash)
				break;
			uline(offs, vp1, vp2);
			ucopy(vp1, vp2);
			++offs;
		}
		if (offs == nrow - 1) {		/* Might get it all.	*/
			ttmove(currow, curcol - lbound);
			ttflush();
			return;
		}
		size = nrow - 1;		/* Get bottom match.	*/
		while (size != offs) {
			vp1 = vscreen[size - 1];
			vp2 = pscreen[size - 1];
			if (vp1->v_color != vp2->v_color
			    || vp1->v_hash != vp2->v_hash)
				break;
			uline(size - 1, vp1, vp2);
			ucopy(vp1, vp2);
			--size;
		}
		if ((size -= offs) == 0)	/* Get screen size.	*/
			panic("Illegal screen size in update");
		setscores(offs, size);		/* Do hard update.	*/
		traceback(offs, size, size, size);
		for (i = 0; i < size; ++i)
			ucopy(vscreen[offs + i], pscreen[offs + i]);
		ttmove(currow, curcol - lbound);
		ttflush();
		return;
	}
	for (i = 0; i < nrow - 1; ++i) {	/* Easy update.		*/
		vp1 = vscreen[i];
		vp2 = pscreen[i];
		if ((vp1->v_flag & VFCHG) != 0) {
			uline(i, vp1, vp2);
			ucopy(vp1, vp2);
		}
	}
	ttmove(currow, curcol - lbound);
	ttflush();
}

/*
 * Update a saved copy of a line,
 * kept in a video structure. The "vvp" is
 * the one in the "vscreen". The "pvp" is the one
 * in the "pscreen". This is called to make the
 * virtual and physical screens the same when
 * display has done an update.
 */
void
ucopy(struct video *vvp, struct video *pvp)
{
	vvp->v_flag &= ~VFCHG;		/* Changes done.	 */
	pvp->v_flag = vvp->v_flag;	/* Update model.	 */
	pvp->v_hash = vvp->v_hash;
	pvp->v_cost = vvp->v_cost;
	pvp->v_color = vvp->v_color;
	bcopy(vvp->v_text, pvp->v_text, ncol);
}

/*
 * updext: update the extended line which the cursor is currently on at a
 * column greater than the terminal width. The line will be scrolled right or
 * left to let the user see where the cursor is.
 */
void
updext(int currow, int curcol)
{
	struct line	*lp;			/* pointer to current line */
	int	 j;			/* index into line */

	if (ncol < 2)
		return;

	/*
	 * calculate what column the left bound should be
	 * (force cursor into middle half of screen)
	 */
	lbound = curcol - (curcol % (ncol >> 1)) - (ncol >> 2);

	/*
	 * scan through the line outputing characters to the virtual screen
	 * once we reach the left edge
	 */
	vtmove(currow, -lbound);		/* start scanning offscreen */
	lp = curwp->w_dotp;			/* line to output */
	for (j = 0; j < llength(lp); ++j)	/* until the end-of-line */
		vtpute(lgetc(lp, j));
	vteeol();				/* truncate the virtual line */
	vscreen[currow]->v_text[0] = '$';	/* and put a '$' in column 1 */
}

/*
 * Update a single line. This routine only
 * uses basic functionality (no insert and delete character,
 * but erase to end of line). The "vvp" points at the video
 * structure for the line on the virtual screen, and the "pvp"
 * is the same for the physical screen. Avoid erase to end of
 * line when updating CMODE color lines, because of the way that
 * reverse video works on most terminals.
 */
void
uline(int row, struct video *vvp, struct video *pvp)
{
	char  *cp1;
	char  *cp2;
	char  *cp3;
	char  *cp4;
	char  *cp5;
	int    nbflag;

	if (vvp->v_color != pvp->v_color) {	/* Wrong color, do a	 */
		ttmove(row, 0);			/* full redraw.		 */
#ifdef	STANDOUT_GLITCH
		if (pvp->v_color != CTEXT && magic_cookie_glitch >= 0)
			tteeol();
#endif
		ttcolor(vvp->v_color);
#ifdef	STANDOUT_GLITCH
		cp1 = &vvp->v_text[magic_cookie_glitch > 0 ? magic_cookie_glitch : 0];
		/*
		 * The odd code for magic_cookie_glitch==0 is to avoid
		 * putting the invisible glitch character on the next line.
		 * (Hazeltine executive 80 model 30)
		 */
		cp2 = &vvp->v_text[ncol - (magic_cookie_glitch >= 0 ?
		    (magic_cookie_glitch != 0 ? magic_cookie_glitch : 1) : 0)];
#else
		cp1 = &vvp->v_text[0];
		cp2 = &vvp->v_text[ncol];
#endif
		while (cp1 != cp2) {
			ttputc(*cp1++);
			++ttcol;
		}
#ifndef MOVE_STANDOUT
		ttcolor(CTEXT);
#endif
		return;
	}
	cp1 = &vvp->v_text[0];		/* Compute left match.	 */
	cp2 = &pvp->v_text[0];
	while (cp1 != &vvp->v_text[ncol] && cp1[0] == cp2[0]) {
		++cp1;
		++cp2;
	}
	if (cp1 == &vvp->v_text[ncol])	/* All equal.		 */
		return;
	nbflag = FALSE;
	cp3 = &vvp->v_text[ncol];	/* Compute right match.  */
	cp4 = &pvp->v_text[ncol];
	while (cp3[-1] == cp4[-1]) {
		--cp3;
		--cp4;
		if (cp3[0] != ' ')	/* Note non-blanks in	 */
			nbflag = TRUE;	/* the right match.	 */
	}
	cp5 = cp3;			/* Is erase good?	 */
	if (nbflag == FALSE && vvp->v_color == CTEXT) {
		while (cp5 != cp1 && cp5[-1] == ' ')
			--cp5;
		/* Alcyon hack */
		if ((int) (cp3 - cp5) <= tceeol)
			cp5 = cp3;
	}
	/* Alcyon hack */
	ttmove(row, (int) (cp1 - &vvp->v_text[0]));
#ifdef	STANDOUT_GLITCH
	if (vvp->v_color != CTEXT && magic_cookie_glitch > 0) {
		if (cp1 < &vvp->v_text[magic_cookie_glitch])
			cp1 = &vvp->v_text[magic_cookie_glitch];
		if (cp5 > &vvp->v_text[ncol - magic_cookie_glitch])
			cp5 = &vvp->v_text[ncol - magic_cookie_glitch];
	} else if (magic_cookie_glitch < 0)
#endif
		ttcolor(vvp->v_color);
	while (cp1 != cp5) {
		ttputc(*cp1++);
		++ttcol;
	}
	if (cp5 != cp3)			/* Do erase.		 */
		tteeol();
}

/*
 * Redisplay the mode line for the window pointed to by the "wp".
 * This is the only routine that has any idea of how the mode line is
 * formatted. You can change the modeline format by hacking at this
 * routine. Called by "update" any time there is a dirty window.  Note
 * that if STANDOUT_GLITCH is defined, first and last magic_cookie_glitch
 * characters may never be seen.
 */
void
modeline(struct mgwin *wp)
{
	int	n, md;
	struct buffer *bp;
	char sl[21];		/* Overkill. Space for 2^64 in base 10. */
	int len;

	n = wp->w_toprow + wp->w_ntrows;	/* Location.		 */
	vscreen[n]->v_color = CMODE;		/* Mode line color.	 */
	vscreen[n]->v_flag |= (VFCHG | VFHBAD);	/* Recompute, display.	 */
	vtmove(n, 0);				/* Seek to right line.	 */
	bp = wp->w_bufp;
	vtputc('-');
	vtputc('-');
	if ((bp->b_flag & BFREADONLY) != 0) {
		vtputc('%');
		if ((bp->b_flag & BFCHG) != 0)
			vtputc('*');
		else
			vtputc('%');
	} else if ((bp->b_flag & BFCHG) != 0) {	/* "*" if changed.	 */
		vtputc('*');
		vtputc('*');
	} else {
		vtputc('-');
		vtputc('-');
	}
	vtputc('-');
	n = 5;
	n += vtputs("Mg: ");
	if (bp->b_bname[0] != '\0')
		n += vtputs(&(bp->b_bname[0]));
	while (n < 42) {			/* Pad out with blanks.	 */
		vtputc(' ');
		++n;
	}
	vtputc('(');
	++n;
	for (md = 0; ; ) {
		n += vtputs(bp->b_modes[md]->p_name);
		if (++md > bp->b_nmodes)
			break;
		vtputc('-');
		++n;
	}
	/* XXX These should eventually move to a real mode */
	if (macrodef == TRUE)
		n += vtputs("-def");
	if (globalwd == TRUE)
		n += vtputs("-gwd");
	vtputc(')');
	++n;

	if (linenos) {
		len = snprintf(sl, sizeof(sl), "--L%d--C%d", wp->w_dotline,
		    wp->w_doto);
		if (len < sizeof(sl) && len != -1)
			n += vtputs(sl);
	}

	while (n < ncol) {			/* Pad out.		 */
		vtputc('-');
		++n;
	}
}

/*
 * Output a string to the mode line, report how long it was.
 */
int
vtputs(const char *s)
{
	int n = 0;

	while (*s != '\0') {
		vtputc(*s++);
		++n;
	}
	return (n);
}

/*
 * Compute the hash code for the line pointed to by the "vp".
 * Recompute it if necessary. Also set the approximate redisplay
 * cost. The validity of the hash code is marked by a flag bit.
 * The cost understand the advantages of erase to end of line.
 * Tuned for the VAX by Bob McNamara; better than it used to be on
 * just about any machine.
 */
void
hash(struct video *vp)
{
	int	i, n;
	char   *s;

	if ((vp->v_flag & VFHBAD) != 0) {	/* Hash bad.		 */
		s = &vp->v_text[ncol - 1];
		for (i = ncol; i != 0; --i, --s)
			if (*s != ' ')
				break;
		n = ncol - i;			/* Erase cheaper?	 */
		if (n > tceeol)
			n = tceeol;
		vp->v_cost = i + n;		/* Bytes + blanks.	 */
		for (n = 0; i != 0; --i, --s)
			n = (n << 5) + n + *s;
		vp->v_hash = n;			/* Hash code.		 */
		vp->v_flag &= ~VFHBAD;		/* Flag as all done.	 */
	}
}

/*
 * Compute the Insert-Delete
 * cost matrix. The dynamic programming algorithm
 * described by James Gosling is used. This code assumes
 * that the line above the echo line is the last line involved
 * in the scroll region. This is easy to arrange on the VT100
 * because of the scrolling region. The "offs" is the origin 0
 * offset of the first row in the virtual/physical screen that
 * is being updated; the "size" is the length of the chunk of
 * screen being updated. For a full screen update, use offs=0
 * and size=nrow-1.
 *
 * Older versions of this code implemented the score matrix by
 * a two dimensional array of SCORE nodes. This put all kinds of
 * multiply instructions in the code! This version is written to
 * use a linear array and pointers, and contains no multiplication
 * at all. The code has been carefully looked at on the VAX, with
 * only marginal checking on other machines for efficiency. In
 * fact, this has been tuned twice! Bob McNamara tuned it even
 * more for the VAX, which is a big issue for him because of
 * the 66 line X displays.
 *
 * On some machines, replacing the "for (i=1; i<=size; ++i)" with
 * i = 1; do { } while (++i <=size)" will make the code quite a
 * bit better; but it looks ugly.
 */
void
setscores(int offs, int size)
{
	struct score	 *sp;
	struct score	 *sp1;
	struct video	**vp, **pp;
	struct video	**vbase, **pbase;
	int	  tempcost;
	int	  bestcost;
	int	  j, i;

	vbase = &vscreen[offs - 1];	/* By hand CSE's.	 */
	pbase = &pscreen[offs - 1];
	score[0].s_itrace = 0;		/* [0, 0]		 */
	score[0].s_jtrace = 0;
	score[0].s_cost = 0;
	sp = &score[1];			/* Row 0, inserts.	 */
	tempcost = 0;
	vp = &vbase[1];
	for (j = 1; j <= size; ++j) {
		sp->s_itrace = 0;
		sp->s_jtrace = j - 1;
		tempcost += tcinsl;
		tempcost += (*vp)->v_cost;
		sp->s_cost = tempcost;
		++vp;
		++sp;
	}
	sp = &score[nrow];		/* Column 0, deletes.	 */
	tempcost = 0;
	for (i = 1; i <= size; ++i) {
		sp->s_itrace = i - 1;
		sp->s_jtrace = 0;
		tempcost += tcdell;
		sp->s_cost = tempcost;
		sp += nrow;
	}
	sp1 = &score[nrow + 1];		/* [1, 1].		 */
	pp = &pbase[1];
	for (i = 1; i <= size; ++i) {
		sp = sp1;
		vp = &vbase[1];
		for (j = 1; j <= size; ++j) {
			sp->s_itrace = i - 1;
			sp->s_jtrace = j;
			bestcost = (sp - nrow)->s_cost;
			if (j != size)	/* Cd(A[i])=0 @ Dis.	 */
				bestcost += tcdell;
			tempcost = (sp - 1)->s_cost;
			tempcost += (*vp)->v_cost;
			if (i != size)	/* Ci(B[j])=0 @ Dsj.	 */
				tempcost += tcinsl;
			if (tempcost < bestcost) {
				sp->s_itrace = i;
				sp->s_jtrace = j - 1;
				bestcost = tempcost;
			}
			tempcost = (sp - nrow - 1)->s_cost;
			if ((*pp)->v_color != (*vp)->v_color
			    || (*pp)->v_hash != (*vp)->v_hash)
				tempcost += (*vp)->v_cost;
			if (tempcost < bestcost) {
				sp->s_itrace = i - 1;
				sp->s_jtrace = j - 1;
				bestcost = tempcost;
			}
			sp->s_cost = bestcost;
			++sp;		/* Next column.		 */
			++vp;
		}
		++pp;
		sp1 += nrow;		/* Next row.		 */
	}
}

/*
 * Trace back through the dynamic programming cost
 * matrix, and update the screen using an optimal sequence
 * of redraws, insert lines, and delete lines. The "offs" is
 * the origin 0 offset of the chunk of the screen we are about to
 * update. The "i" and "j" are always started in the lower right
 * corner of the matrix, and imply the size of the screen.
 * A full screen traceback is called with offs=0 and i=j=nrow-1.
 * There is some do-it-yourself double subscripting here,
 * which is acceptable because this routine is much less compute
 * intensive then the code that builds the score matrix!
 */
void
traceback(int offs, int size, int i, int j)
{
	int	itrace, jtrace;
	int	k;
	int	ninsl, ndraw, ndell;

	if (i == 0 && j == 0)	/* End of update.	 */
		return;
	itrace = score[(nrow * i) + j].s_itrace;
	jtrace = score[(nrow * i) + j].s_jtrace;
	if (itrace == i) {	/* [i, j-1]		 */
		ninsl = 0;	/* Collect inserts.	 */
		if (i != size)
			ninsl = 1;
		ndraw = 1;
		while (itrace != 0 || jtrace != 0) {
			if (score[(nrow * itrace) + jtrace].s_itrace != itrace)
				break;
			jtrace = score[(nrow * itrace) + jtrace].s_jtrace;
			if (i != size)
				++ninsl;
			++ndraw;
		}
		traceback(offs, size, itrace, jtrace);
		if (ninsl != 0) {
			ttcolor(CTEXT);
			ttinsl(offs + j - ninsl, offs + size - 1, ninsl);
		}
		do {		/* B[j], A[j] blank.	 */
			k = offs + j - ndraw;
			uline(k, vscreen[k], &blanks);
		} while (--ndraw);
		return;
	}
	if (jtrace == j) {	/* [i-1, j]		 */
		ndell = 0;	/* Collect deletes.	 */
		if (j != size)
			ndell = 1;
		while (itrace != 0 || jtrace != 0) {
			if (score[(nrow * itrace) + jtrace].s_jtrace != jtrace)
				break;
			itrace = score[(nrow * itrace) + jtrace].s_itrace;
			if (j != size)
				++ndell;
		}
		if (ndell != 0) {
			ttcolor(CTEXT);
			ttdell(offs + i - ndell, offs + size - 1, ndell);
		}
		traceback(offs, size, itrace, jtrace);
		return;
	}
	traceback(offs, size, itrace, jtrace);
	k = offs + j - 1;
	uline(k, vscreen[k], pscreen[offs + i - 1]);
}