X-Git-Url: https://pd.if.org/git/?p=pd_readline;a=blobdiff_plain;f=mg%2Fdisplay.c;fp=mg%2Fdisplay.c;h=ba7c580e9c5b75cdbcfff5c90914d163e1ce4e8a;hp=0000000000000000000000000000000000000000;hb=a9843085ec916c175bd245a8398f30e6cc03f984;hpb=26fe4e09c6c3c250334fdeed60ce3061febecde2

diff --git a/mg/display.c b/mg/display.c
new file mode 100644
index 0000000..ba7c580
--- /dev/null
+++ b/mg/display.c
@@ -0,0 +1,1064 @@
+/*	$OpenBSD: display.c,v 1.37 2009/06/04 02:23:37 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_rflag |= WFMODE | WFFULL;
+			wp = wp->w_wndp;
+		}
+	}
+	if (linenos) {
+		wp = wheadp;
+		while (wp != NULL) {
+			wp->w_rflag |= 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_rflag == 0)
+			continue;
+
+		if ((wp->w_rflag & 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_rflag |= WFFULL;	/* Force full.		 */
+	out:
+		lp = wp->w_linep;	/* Try reduced update.	 */
+		i = wp->w_toprow;
+		if ((wp->w_rflag & ~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_rflag & (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_rflag & WFMODE) != 0)
+			modeline(wp);
+		wp->w_rflag = 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,
+		    getcolpos());
+		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]);
+}