uemacs/display.c

/* display.c -- implements display.h */

#include "display.h"

/*	display.c
 *
 *      The functions in this file handle redisplay. There are two halves, the
 *      ones that update the virtual display screen, and the ones that make the
 *      physical display screen the same as the virtual display screen. These
 *      functions use hints that are left in the windows by the commands.
 *
 *	Modified by Petri Kutvonen
 */

#include <errno.h>
#include <stdio.h>
#include <stdarg.h>
#include <unistd.h>

#include "estruct.h"
#include "edef.h"
#include "line.h"
#include "termio.h"
#include "version.h"
#include "wrapper.h"
#include "utf8.h"
#include "window.h"

struct video {
	int v_flag;		/* Flags */
#if	COLOR
	int v_fcolor;		/* current forground color */
	int v_bcolor;		/* current background color */
	int v_rfcolor;		/* requested forground color */
	int v_rbcolor;		/* requested background color */
#endif
	unicode_t v_text[1];	/* Screen data. */
};

#define VFCHG   0x0001		/* Changed flag                 */
#define	VFEXT	0x0002		/* extended (beyond column 80)  */
#define	VFREV	0x0004		/* reverse video status         */
#define	VFREQ	0x0008		/* reverse video request        */
#define	VFCOL	0x0010		/* color change requested       */

static struct video **vscreen;		/* Virtual screen. */
#if	MEMMAP == 0 || SCROLLCODE
static struct video **pscreen;		/* Physical screen. */
#endif

static int displaying = TRUE;
#if UNIX
#include <signal.h>
#endif
#ifdef SIGWINCH
#include <sys/ioctl.h>
/* for window size changes */
int chg_width, chg_height;
#endif

static int reframe(struct window *wp);
static void updone(struct window *wp);
static void updall(struct window *wp);
static int scrolls(int inserts);
static void scrscroll(int from, int to, int count);
static int texttest(int vrow, int prow);
static int endofline(unicode_t *s, int n);
static void updext(void);
static int updateline(int row, struct video *vp1, struct video *vp2);
static void modeline(struct window *wp);
static void mlputi(int i, int r);
static void mlputli(long l, int r);
static void mlputf(int s);
static int newscreensize(int h, int w);

#if RAINBOW
static void putline(int row, int col, char *buf);
#endif

/*
 * 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. All the other things get initialized at compile time.
 * The original window has "WFCHG" set, so that it will get completely
 * redrawn on the first call to "update".
 */
void vtinit(void)
{
	int i;
	struct video *vp;

	TTopen();		/* open the screen */
	TTkopen();		/* open the keyboard */
	TTrev(FALSE);
	vscreen = xmalloc(term.t_mrow * sizeof(struct video *));

#if	MEMMAP == 0 || SCROLLCODE
	pscreen = xmalloc(term.t_mrow * sizeof(struct video *));
#endif
	for (i = 0; i < term.t_mrow; ++i) {
		vp = xmalloc(sizeof(struct video) + term.t_mcol*4);
		vp->v_flag = 0;
#if	COLOR
		vp->v_rfcolor = 7;
		vp->v_rbcolor = 0;
#endif
		vscreen[i] = vp;
#if	MEMMAP == 0 || SCROLLCODE
		vp = xmalloc(sizeof(struct video) + term.t_mcol*4);
		vp->v_flag = 0;
		pscreen[i] = vp;
#endif
	}
}

#if	CLEAN
/* free up all the dynamically allocated video structures */

void vtfree(void)
{
	int i;
	for (i = 0; i < term.t_mrow; ++i) {
		free(vscreen[i]);
#if	MEMMAP == 0 || SCROLLCODE
		free(pscreen[i]);
#endif
	}
	free(vscreen);
#if	MEMMAP == 0 || SCROLLCODE
	free(pscreen);
#endif
}
#endif

/*
 * Clean up the virtual terminal system, in anticipation for a return to the
 * operating system. Move down to the last line and clear it out (the next
 * system prompt will be written in the line). Shut down the channel to the
 * terminal.
 */
void vttidy(void)
{
	mlerase();
	movecursor(term.t_nrow, 0);
	TTflush();
	TTclose();
	TTkclose();
#ifdef PKCODE
	write(1, "\r", 1);
#endif
}

/*
 * Set the virtual cursor to the specified row and column on the virtual
 * screen. There is no checking for nonsense values; this might be a good
 * idea during the early stages.
 */
void vtmove(int row, int col)
{
	vtrow = row;
	vtcol = col;
}

/*
 * Write a character to the virtual screen. The virtual row and
 * column are updated. If we are not yet on left edge, don't print
 * it yet. If the line is too long put a "$" in the last column.
 *
 * This routine only puts printing characters into the virtual
 * terminal buffers. Only column overflow is checked.
 */
static void vtputc(int c)
{
	struct video *vp;	/* ptr to line being updated */

	/* In case somebody passes us a signed char.. */
	if (c < 0) {
		c += 256;
		if (c < 0)
			return;
	}

	vp = vscreen[vtrow];

	if (vtcol >= term.t_ncol) {
		++vtcol;
		vp->v_text[term.t_ncol - 1] = '$';
		return;
	}

	if (c == '\t') {
		do {
			vtputc(' ');
		} while (((vtcol + taboff) & tabmask) != 0);
		return;
	}

	if (c < 0x20) {
		vtputc('^');
		vtputc(c ^ 0x40);
		return;
	}

	if (c == 0x7f) {
		vtputc('^');
		vtputc('?');
		return;
	}

	if (c >= 0x80 && c <= 0xA0) {
		static const char hex[] = "0123456789abcdef";
		vtputc('\\');
		vtputc(hex[c >> 4]);
		vtputc(hex[c & 15]);
		return;
	}
	
	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.
 */
static void vteeol(void)
{
/*  struct video *vp;	*/
	unicode_t *vcp = vscreen[vtrow]->v_text;

/*  vp = vscreen[vtrow];	*/
	while (vtcol < term.t_ncol)
/*	vp->v_text[vtcol++] = ' ';	*/
		vcp[vtcol++] = ' ';
}

/*
 * upscreen:
 *	user routine to force a screen update
 *	always finishes complete update
 */
int upscreen(int f, int n)
{
	update(TRUE);
	return TRUE;
}

#if SCROLLCODE
static int scrflags;
#endif

/*
 * 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.
 *
 * int force;		force update past type ahead?
 */
int update(int force)
{
	struct window *wp;

#if	TYPEAH && ! PKCODE
	if (force == FALSE && typahead())
		return TRUE;
#endif
#if	VISMAC == 0
	if (force == FALSE && kbdmode == PLAY)
		return TRUE;
#endif

	displaying = TRUE;

#if SCROLLCODE

	/* first, propagate mode line changes to all instances of
	   a buffer displayed in more than one window */
	wp = wheadp;
	while (wp != NULL) {
		if (wp->w_flag & WFMODE) {
			if (wp->w_bufp->b_nwnd > 1) {
				/* make sure all previous windows have this */
				struct window *owp;
				owp = wheadp;
				while (owp != NULL) {
					if (owp->w_bufp == wp->w_bufp)
						owp->w_flag |= WFMODE;
					owp = owp->w_wndp;
				}
			}
		}
		wp = wp->w_wndp;
	}

#endif

	/* update any windows that need refreshing */
	wp = wheadp;
	while (wp != NULL) {
		if (wp->w_flag) {
			/* if the window has changed, service it */
			reframe(wp);	/* check the framing */
#if SCROLLCODE
			if (wp->w_flag & (WFKILLS | WFINS)) {
				scrflags |=
				    (wp->w_flag & (WFINS | WFKILLS));
				wp->w_flag &= ~(WFKILLS | WFINS);
			}
#endif
			if ((wp->w_flag & ~WFMODE) == WFEDIT)
				updone(wp);	/* update EDITed line */
			else if (wp->w_flag & ~WFMOVE)
				updall(wp);	/* update all lines */
#if SCROLLCODE
			if (scrflags || (wp->w_flag & WFMODE))
#else
			if (wp->w_flag & WFMODE)
#endif
				modeline(wp);	/* update modeline */
			wp->w_flag = 0;
			wp->w_force = 0;
		}
		/* on to the next window */
		wp = wp->w_wndp;
	}

	/* recalc the current hardware cursor location */
	updpos();

#if	MEMMAP && ! SCROLLCODE
	/* update the cursor and flush the buffers */
	movecursor(currow, curcol - lbound);
#endif

	/* check for lines to de-extend */
	upddex();

	/* if screen is garbage, re-plot it */
	if (sgarbf != FALSE)
		updgar();

	/* update the virtual screen to the physical screen */
	updupd(force);

	/* update the cursor and flush the buffers */
	movecursor(currow, curcol - lbound);
	TTflush();
	displaying = FALSE;
#if SIGWINCH
	while (chg_width || chg_height)
		newscreensize(chg_height, chg_width);
#endif
	return TRUE;
}

/*
 * reframe:
 *	check to see if the cursor is on in the window
 *	and re-frame it if needed or wanted
 */
static int reframe(struct window *wp)
{
	struct line *lp, *lp0;
	int i = 0;

	/* if not a requested reframe, check for a needed one */
	if ((wp->w_flag & WFFORCE) == 0) {
#if SCROLLCODE
		/* loop from one line above the window to one line after */
		lp = wp->w_linep;
		lp0 = lback(lp);
		if (lp0 == wp->w_bufp->b_linep)
			i = 0;
		else {
			i = -1;
			lp = lp0;
		}
		for (; i <= (int) (wp->w_ntrows); i++)
#else
		lp = wp->w_linep;
		for (i = 0; i < wp->w_ntrows; i++)
#endif
		{
			/* if the line is in the window, no reframe */
			if (lp == wp->w_dotp) {
#if SCROLLCODE
				/* if not _quite_ in, we'll reframe gently */
				if (i < 0 || i == wp->w_ntrows) {
					/* if the terminal can't help, then
					   we're simply outside */
					if (term.t_scroll == NULL)
						i = wp->w_force;
					break;
				}
#endif
				return TRUE;
			}

			/* if we are at the end of the file, reframe */
			if (lp == wp->w_bufp->b_linep)
				break;

			/* on to the next line */
			lp = lforw(lp);
		}
	}
#if SCROLLCODE
	if (i == -1) {		/* we're just above the window */
		i = scrollcount;	/* put dot at first line */
		scrflags |= WFINS;
	} else if (i == wp->w_ntrows) {	/* we're just below the window */
		i = -scrollcount;	/* put dot at last line */
		scrflags |= WFKILLS;
	} else			/* put dot where requested */
#endif
		i = wp->w_force;	/* (is 0, unless reposition() was called) */

	wp->w_flag |= WFMODE;

	/* how far back to reframe? */
	if (i > 0) {		/* only one screen worth of lines max */
		if (--i >= wp->w_ntrows)
			i = wp->w_ntrows - 1;
	} else if (i < 0) {	/* negative update???? */
		i += wp->w_ntrows;
		if (i < 0)
			i = 0;
	} else
		i = wp->w_ntrows / 2;

	/* backup to new line at top of window */
	lp = wp->w_dotp;
	while (i != 0 && lback(lp) != wp->w_bufp->b_linep) {
		--i;
		lp = lback(lp);
	}

	/* and reset the current line at top of window */
	wp->w_linep = lp;
	wp->w_flag |= WFHARD;
	wp->w_flag &= ~WFFORCE;
	return TRUE;
}

static void show_line(struct line *lp)
{
	int i = 0, len = llength(lp);

	while (i < len) {
		unicode_t c;
		i += utf8_to_unicode(lp->l_text, i, len, &c);
		vtputc(c);
	}
}

/*
 * updone:
 *	update the current line	to the virtual screen
 *
 * struct window *wp;		window to update current line in
 */
static void updone(struct window *wp)
{
	struct line *lp;	/* line to update */
	int sline;	/* physical screen line to update */

	/* search down the line we want */
	lp = wp->w_linep;
	sline = wp->w_toprow;
	while (lp != wp->w_dotp) {
		++sline;
		lp = lforw(lp);
	}

	/* and update the virtual line */
	vscreen[sline]->v_flag |= VFCHG;
	vscreen[sline]->v_flag &= ~VFREQ;
	vtmove(sline, 0);
	show_line(lp);
#if	COLOR
	vscreen[sline]->v_rfcolor = wp->w_fcolor;
	vscreen[sline]->v_rbcolor = wp->w_bcolor;
#endif
	vteeol();
}

/*
 * updall:
 *	update all the lines in a window on the virtual screen
 *
 * struct window *wp;		window to update lines in
 */
static void updall(struct window *wp)
{
	struct line *lp;	/* line to update */
	int sline;	/* physical screen line to update */

	/* search down the lines, updating them */
	lp = wp->w_linep;
	sline = wp->w_toprow;
	while (sline < wp->w_toprow + wp->w_ntrows) {

		/* and update the virtual line */
		vscreen[sline]->v_flag |= VFCHG;
		vscreen[sline]->v_flag &= ~VFREQ;
		vtmove(sline, 0);
		if (lp != wp->w_bufp->b_linep) {
			/* if we are not at the end */
			show_line(lp);
			lp = lforw(lp);
		}

		/* on to the next one */
#if	COLOR
		vscreen[sline]->v_rfcolor = wp->w_fcolor;
		vscreen[sline]->v_rbcolor = wp->w_bcolor;
#endif
		vteeol();
		++sline;
	}

}

/*
 * updpos:
 *	update the position of the hardware cursor and handle extended
 *	lines. This is the only update for simple moves.
 */
void updpos(void)
{
	struct line *lp;
	int i;

	/* find the current row */
	lp = curwp->w_linep;
	currow = curwp->w_toprow;
	while (lp != curwp->w_dotp) {
		++currow;
		lp = lforw(lp);
	}

	/* find the current column */
	curcol = 0;
	i = 0;
	while (i < curwp->w_doto) {
		unicode_t c;
		int bytes;

		bytes = utf8_to_unicode(lp->l_text, i, curwp->w_doto, &c);
		i += bytes;
		if (c == '\t')
			curcol |= tabmask;

		++curcol;
	}

	/* if extended, flag so and update the virtual line image */
	if (curcol >= term.t_ncol - 1) {
		vscreen[currow]->v_flag |= (VFEXT | VFCHG);
		updext();
	} else
		lbound = 0;
}

/*
 * upddex:
 *	de-extend any line that derserves it
 */
void upddex(void)
{
	struct window *wp;
	struct line *lp;
	int i;

	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) {
				if ((wp != curwp) || (lp != wp->w_dotp) ||
				    (curcol < term.t_ncol - 1)) {
					vtmove(i, 0);
					show_line(lp);
					vteeol();

					/* this line no longer is extended */
					vscreen[i]->v_flag &= ~VFEXT;
					vscreen[i]->v_flag |= VFCHG;
				}
			}
			lp = lforw(lp);
			++i;
		}
		/* and onward to the next window */
		wp = wp->w_wndp;
	}
}

/*
 * updgar:
 *	if the screen is garbage, clear the physical screen and
 *	the virtual screen and force a full update
 */
void updgar(void)
{
	unicode_t *txt;
	int i, j;

	for (i = 0; i < term.t_nrow; ++i) {
		vscreen[i]->v_flag |= VFCHG;
#if	REVSTA
		vscreen[i]->v_flag &= ~VFREV;
#endif
#if	COLOR
		vscreen[i]->v_fcolor = gfcolor;
		vscreen[i]->v_bcolor = gbcolor;
#endif
#if	MEMMAP == 0 || SCROLLCODE
		txt = pscreen[i]->v_text;
		for (j = 0; j < term.t_ncol; ++j)
			txt[j] = ' ';
#endif
	}

	movecursor(0, 0);	/* Erase the screen. */
	(*term.t_eeop) ();
	sgarbf = FALSE;		/* Erase-page clears */
	mpresf = FALSE;		/* the message area. */
#if	COLOR
	mlerase();		/* needs to be cleared if colored */
#endif
}

/*
 * updupd:
 *	update the physical screen from the virtual screen
 *
 * int force;		forced update flag
 */
int updupd(int force)
{
	struct video *vp1;
	int i;

#if SCROLLCODE
	if (scrflags & WFKILLS)
		scrolls(FALSE);
	if (scrflags & WFINS)
		scrolls(TRUE);
	scrflags = 0;
#endif

	for (i = 0; i < term.t_nrow; ++i) {
		vp1 = vscreen[i];

		/* for each line that needs to be updated */
		if ((vp1->v_flag & VFCHG) != 0) {
#if	TYPEAH && ! PKCODE
			if (force == FALSE && typahead())
				return TRUE;
#endif
#if	MEMMAP && ! SCROLLCODE
			updateline(i, vp1);
#else
			updateline(i, vp1, pscreen[i]);
#endif
		}
	}
	return TRUE;
}

#if SCROLLCODE

/*
 * optimize out scrolls (line breaks, and newlines)
 * arg. chooses between looking for inserts or deletes
 */
static int scrolls(int inserts)
{				/* returns true if it does something */
	struct video *vpv;	/* virtual screen image */
	struct video *vpp;	/* physical screen image */
	int i, j, k;
	int rows, cols;
	int first, match, count, target, end;
	int longmatch, longcount;
	int from, to;

	if (!term.t_scroll)	/* no way to scroll */
		return FALSE;

	rows = term.t_nrow;
	cols = term.t_ncol;

	first = -1;
	for (i = 0; i < rows; i++) {	/* find first wrong line */
		if (!texttest(i, i)) {
			first = i;
			break;
		}
	}

	if (first < 0)
		return FALSE;	/* no text changes */

	vpv = vscreen[first];
	vpp = pscreen[first];

	if (inserts) {
		/* determine types of potential scrolls */
		end = endofline(vpv->v_text, cols);
		if (end == 0)
			target = first;	/* newlines */
		else if (memcmp(vpp->v_text, vpv->v_text, 4*end) == 0)
			target = first + 1;	/* broken line newlines */
		else
			target = first;
	} else {
		target = first + 1;
	}

	/* find the matching shifted area */
	match = -1;
	longmatch = -1;
	longcount = 0;
	from = target;
	for (i = from + 1; i < rows - longcount /* P.K. */ ; i++) {
		if (inserts ? texttest(i, from) : texttest(from, i)) {
			match = i;
			count = 1;
			for (j = match + 1, k = from + 1;
			     j < rows && k < rows; j++, k++) {
				if (inserts ? texttest(j, k) :
				    texttest(k, j))
					count++;
				else
					break;
			}
			if (longcount < count) {
				longcount = count;
				longmatch = match;
			}
		}
	}
	match = longmatch;
	count = longcount;

	if (!inserts) {
		/* full kill case? */
		if (match > 0 && texttest(first, match - 1)) {
			target--;
			match--;
			count++;
		}
	}

	/* do the scroll */
	if (match > 0 && count > 2) {	/* got a scroll */
		/* move the count lines starting at target to match */
		if (inserts) {
			from = target;
			to = match;
		} else {
			from = match;
			to = target;
		}
		if (2 * count < abs(from - to))
			return FALSE;
		scrscroll(from, to, count);
		for (i = 0; i < count; i++) {
			vpp = pscreen[to + i];
			vpv = vscreen[to + i];
			memcpy(vpp->v_text, vpv->v_text, 4*cols);
			vpp->v_flag = vpv->v_flag;	/* XXX */
			if (vpp->v_flag & VFREV) {
				vpp->v_flag &= ~VFREV;
				vpp->v_flag |= ~VFREQ;
			}
#if	MEMMAP
			vscreen[to + i]->v_flag &= ~VFCHG;
#endif
		}
		if (inserts) {
			from = target;
			to = match;
		} else {
			from = target + count;
			to = match + count;
		}
#if	MEMMAP == 0
		for (i = from; i < to; i++) {
			unicode_t *txt;
			txt = pscreen[i]->v_text;
			for (j = 0; j < term.t_ncol; ++j)
				txt[j] = ' ';
			vscreen[i]->v_flag |= VFCHG;
		}
#endif
		return TRUE;
	}
	return FALSE;
}

/* move the "count" lines starting at "from" to "to" */
static void scrscroll(int from, int to, int count)
{
	ttrow = ttcol = -1;
	(*term.t_scroll) (from, to, count);
}

/*
 * return TRUE on text match
 *
 * int vrow, prow;		virtual, physical rows
 */
static int texttest(int vrow, int prow)
{
	struct video *vpv = vscreen[vrow];	/* virtual screen image */
	struct video *vpp = pscreen[prow];	/* physical screen image */

	return !memcmp(vpv->v_text, vpp->v_text, 4*term.t_ncol);
}

/*
 * return the index of the first blank of trailing whitespace
 */
static int endofline(unicode_t *s, int n)
{
	int i;
	for (i = n - 1; i >= 0; i--)
		if (s[i] != ' ')
			return i + 1;
	return 0;
}

#endif				/* SCROLLCODE */

/*
 * 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
 */
static void updext(void)
{
	int rcursor;	/* real cursor location */
	struct line *lp;	/* pointer to current line */

	/* calculate what column the real cursor will end up in */
	rcursor = ((curcol - term.t_ncol) % term.t_scrsiz) + term.t_margin;
	taboff = lbound = curcol - rcursor + 1;

	/* 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 */
	show_line(lp);

	/* truncate the virtual line, restore tab offset */
	vteeol();
	taboff = 0;

	/* and put a '$' in column 1 */
	vscreen[currow]->v_text[0] = '$';
}

/*
 * Update a single line. This does not know how to use insert or delete
 * character sequences; we are using VT52 functionality. Update the physical
 * row and column variables. It does try an exploit erase to end of line. The
 * RAINBOW version of this routine uses fast video.
 */
#if	MEMMAP
/*	UPDATELINE specific code for the IBM-PC and other compatables */

static int updateline(int row, struct video *vp1, struct video *vp2)
{
#if	SCROLLCODE
	unicode_t *cp1;
	unicode_t *cp2;
	int nch;

	cp1 = &vp1->v_text[0];
	cp2 = &vp2->v_text[0];
	nch = term.t_ncol;
	do {
		*cp2 = *cp1;
		++cp2;
		++cp1;
	}
	while (--nch);
#endif
#if	COLOR
	scwrite(row, vp1->v_text, vp1->v_rfcolor, vp1->v_rbcolor);
	vp1->v_fcolor = vp1->v_rfcolor;
	vp1->v_bcolor = vp1->v_rbcolor;
#else
	if (vp1->v_flag & VFREQ)
		scwrite(row, vp1->v_text, 0, 7);
	else
		scwrite(row, vp1->v_text, 7, 0);
#endif
	vp1->v_flag &= ~(VFCHG | VFCOL);	/* flag this line as changed */

}

#else

/*
 * updateline()
 *
 * int row;		row of screen to update
 * struct video *vp1;	virtual screen image
 * struct video *vp2;	physical screen image
 */
static int updateline(int row, struct video *vp1, struct video *vp2)
{
#if RAINBOW
/*	UPDATELINE specific code for the DEC rainbow 100 micro	*/

	unicode_t *cp1;
	unicode_t *cp2;
	int nch;

	/* since we don't know how to make the rainbow do this, turn it off */
	flags &= (~VFREV & ~VFREQ);

	cp1 = &vp1->v_text[0];	/* Use fast video. */
	cp2 = &vp2->v_text[0];
	putline(row + 1, 1, cp1);
	nch = term.t_ncol;

	do {
		*cp2 = *cp1;
		++cp2;
		++cp1;
	}
	while (--nch);
	*flags &= ~VFCHG;
#else
/*	UPDATELINE code for all other versions		*/

	unicode_t *cp1;
	unicode_t *cp2;
	unicode_t *cp3;
	unicode_t *cp4;
	unicode_t *cp5;
	int nbflag;	/* non-blanks to the right flag? */
	int rev;		/* reverse video flag */
	int req;		/* reverse video request flag */


	/* set up pointers to virtual and physical lines */
	cp1 = &vp1->v_text[0];
	cp2 = &vp2->v_text[0];

#if	COLOR
	TTforg(vp1->v_rfcolor);
	TTbacg(vp1->v_rbcolor);
#endif

#if	REVSTA | COLOR
	/* if we need to change the reverse video status of the
	   current line, we need to re-write the entire line     */
	rev = (vp1->v_flag & VFREV) == VFREV;
	req = (vp1->v_flag & VFREQ) == VFREQ;
	if ((rev != req)
#if	COLOR
	    || (vp1->v_fcolor != vp1->v_rfcolor)
	    || (vp1->v_bcolor != vp1->v_rbcolor)
#endif
	    ) {
		movecursor(row, 0);	/* Go to start of line. */
		/* set rev video if needed */
		if (rev != req)
			(*term.t_rev) (req);

		/* scan through the line and dump it to the screen and
		   the virtual screen array                             */
		cp3 = &vp1->v_text[term.t_ncol];
		while (cp1 < cp3) {
			TTputc(*cp1);
			++ttcol;
			*cp2++ = *cp1++;
		}
		/* turn rev video off */
		if (rev != req)
			(*term.t_rev) (FALSE);

		/* update the needed flags */
		vp1->v_flag &= ~VFCHG;
		if (req)
			vp1->v_flag |= VFREV;
		else
			vp1->v_flag &= ~VFREV;
#if	COLOR
		vp1->v_fcolor = vp1->v_rfcolor;
		vp1->v_bcolor = vp1->v_rbcolor;
#endif
		return TRUE;
	}
#endif

	/* advance past any common chars at the left */
	while (cp1 != &vp1->v_text[term.t_ncol] && cp1[0] == cp2[0]) {
		++cp1;
		++cp2;
	}

/* This can still happen, even though we only call this routine on changed
 * lines. A hard update is always done when a line splits, a massive
 * change is done, or a buffer is displayed twice. This optimizes out most
 * of the excess updating. A lot of computes are used, but these tend to
 * be hard operations that do a lot of update, so I don't really care.
 */
	/* if both lines are the same, no update needs to be done */
	if (cp1 == &vp1->v_text[term.t_ncol]) {
		vp1->v_flag &= ~VFCHG;	/* flag this line is changed */
		return TRUE;
	}

	/* find out if there is a match on the right */
	nbflag = FALSE;
	cp3 = &vp1->v_text[term.t_ncol];
	cp4 = &vp2->v_text[term.t_ncol];

	while (cp3[-1] == cp4[-1]) {
		--cp3;
		--cp4;
		if (cp3[0] != ' ')	/* Note if any nonblank */
			nbflag = TRUE;	/* in right match. */
	}

	cp5 = cp3;

	/* Erase to EOL ? */
	if (nbflag == FALSE && eolexist == TRUE && (req != TRUE)) {
		while (cp5 != cp1 && cp5[-1] == ' ')
			--cp5;

		if (cp3 - cp5 <= 3)	/* Use only if erase is */
			cp5 = cp3;	/* fewer characters. */
	}

	movecursor(row, cp1 - &vp1->v_text[0]);	/* Go to start of line. */
#if	REVSTA
	TTrev(rev);
#endif

	while (cp1 != cp5) {	/* Ordinary. */
		TTputc(*cp1);
		++ttcol;
		*cp2++ = *cp1++;
	}

	if (cp5 != cp3) {	/* Erase. */
		TTeeol();
		while (cp1 != cp3)
			*cp2++ = *cp1++;
	}
#if	REVSTA
	TTrev(FALSE);
#endif
	vp1->v_flag &= ~VFCHG;	/* flag this line as updated */
	return TRUE;
#endif
}
#endif

/*
 * Redisplay the mode line for the window pointed to by the "wp". This is the
 * only routine that has any idea of how the modeline is formatted. You can
 * change the modeline format by hacking at this routine. Called by "update"
 * any time there is a dirty window.
 */
static void modeline(struct window *wp)
{
	char *cp;
	int c;
	int n;		/* cursor position count */
	struct buffer *bp;
	int i;		/* loop index */
	int lchar;	/* character to draw line in buffer with */
	int firstm;	/* is this the first mode? */
	char tline[NLINE];	/* buffer for part of mode line */

	n = wp->w_toprow + wp->w_ntrows;	/* Location. */
	vscreen[n]->v_flag |= VFCHG | VFREQ | VFCOL;	/* Redraw next time. */
#if	COLOR
	vscreen[n]->v_rfcolor = 0;	/* black on */
	vscreen[n]->v_rbcolor = 7;	/* white..... */
#endif
	vtmove(n, 0);		/* Seek to right line. */
	if (wp == curwp)	/* mark the current buffer */
#if	PKCODE
		lchar = '-';
#else
		lchar = '=';
#endif
	else
#if	REVSTA
	if (revexist)
		lchar = ' ';
	else
#endif
		lchar = '-';

	bp = wp->w_bufp;
#if	PKCODE == 0
	if ((bp->b_flag & BFTRUNC) != 0)
		vtputc('#');
	else
#endif
		vtputc(lchar);

	if ((bp->b_flag & BFCHG) != 0)	/* "*" if changed. */
		vtputc('*');
	else
		vtputc(lchar);

	n = 2;

	cp = " " PROGRAM_NAME_LONG " " VERSION ": " ;
	while ((c = *cp++) != 0) {
		vtputc(c);
		++n;
	}

	cp = &bp->b_bname[0];
	while ((c = *cp++) != 0) {
		vtputc(c);
		++n;
	}

	strcpy(tline, " (");

	/* display the modes */

	firstm = TRUE;
	if ((bp->b_flag & BFTRUNC) != 0) {
		firstm = FALSE;
		strcat(tline, "Truncated");
	}
	for (i = 0; i < NUMMODES; i++)	/* add in the mode flags */
		if (wp->w_bufp->b_mode & (1 << i)) {
			if (firstm != TRUE)
				strcat(tline, " ");
			firstm = FALSE;
			strcat(tline, mode2name[i]);
		}
	strcat(tline, ") ");

	cp = &tline[0];
	while ((c = *cp++) != 0) {
		vtputc(c);
		++n;
	}

#if	PKCODE
	if (bp->b_fname[0] != 0 && strcmp(bp->b_bname, bp->b_fname) != 0)
#else
	if (bp->b_fname[0] != 0)	/* File name. */
#endif
	{
#if	PKCODE == 0
		cp = "File: ";

		while ((c = *cp++) != 0) {
			vtputc(c);
			++n;
		}
#endif

		cp = &bp->b_fname[0];

		while ((c = *cp++) != 0) {
			vtputc(c);
			++n;
		}

		vtputc(' ');
		++n;
	}

	while (n < term.t_ncol) {	/* Pad to full width. */
		vtputc(lchar);
		++n;
	}

	{			/* determine if top line, bottom line, or both are visible */
		struct line *lp = wp->w_linep;
		int rows = wp->w_ntrows;
		char *msg = NULL;

		vtcol = n - 7;	/* strlen(" top ") plus a couple */
		while (rows--) {
			lp = lforw(lp);
			if (lp == wp->w_bufp->b_linep) {
				msg = " Bot ";
				break;
			}
		}
		if (lback(wp->w_linep) == wp->w_bufp->b_linep) {
			if (msg) {
				if (wp->w_linep == wp->w_bufp->b_linep)
					msg = " Emp ";
				else
					msg = " All ";
			} else {
				msg = " Top ";
			}
		}
		if (!msg) {
			struct line *lp;
			int numlines, predlines, ratio;

			lp = lforw(bp->b_linep);
			numlines = 0;
			predlines = 0;
			while (lp != bp->b_linep) {
				if (lp == wp->w_linep) {
					predlines = numlines;
				}
				++numlines;
				lp = lforw(lp);
			}
			if (wp->w_dotp == bp->b_linep) {
				msg = " Bot ";
			} else {
				ratio = 0;
				if (numlines != 0)
					ratio =
					    (100L * predlines) / numlines;
				if (ratio > 99)
					ratio = 99;
				sprintf(tline, " %2d%% ", ratio);
				msg = tline;
			}
		}

		cp = msg;
		while ((c = *cp++) != 0) {
			vtputc(c);
			++n;
		}
	}
}

void upmode(void)
{				/* update all the mode lines */
	struct window *wp;

	wp = wheadp;
	while (wp != NULL) {
		wp->w_flag |= WFMODE;
		wp = wp->w_wndp;
	}
}

/*
 * Send a command to the terminal to move the hardware cursor to row "row"
 * and column "col". The row and column arguments are origin 0. Optimize out
 * random calls. Update "ttrow" and "ttcol".
 */
void movecursor(int row, int col)
{
	if (row != ttrow || col != ttcol) {
		ttrow = row;
		ttcol = col;
		TTmove(row, col);
	}
}

/*
 * Erase the message line. This is a special routine because the message line
 * is not considered to be part of the virtual screen. It always works
 * immediately; the terminal buffer is flushed via a call to the flusher.
 */
void mlerase(void)
{
	int i;

	movecursor(term.t_nrow, 0);
	if (discmd == FALSE)
		return;

#if	COLOR
	TTforg(7);
	TTbacg(0);
#endif
	if (eolexist == TRUE)
		TTeeol();
	else {
		for (i = 0; i < term.t_ncol - 1; i++)
			TTputc(' ');
		movecursor(term.t_nrow, 1);	/* force the move! */
		movecursor(term.t_nrow, 0);
	}
	TTflush();
	mpresf = FALSE;
}

/*
 * Write a message into the message line. Keep track of the physical cursor
 * position. A small class of printf like format items is handled. Assumes the
 * stack grows down; this assumption is made by the "++" in the argument scan
 * loop. Set the "message line" flag TRUE.
 *
 * char *fmt;		format string for output
 * char *arg;		pointer to first argument to print
 */
void mlwrite(const char *fmt, ...)
{
	int c;		/* current char in format string */
	va_list ap;

	/* if we are not currently echoing on the command line, abort this */
	if (discmd == FALSE) {
		movecursor(term.t_nrow, 0);
		return;
	}
#if	COLOR
	/* set up the proper colors for the command line */
	TTforg(7);
	TTbacg(0);
#endif

	/* if we can not erase to end-of-line, do it manually */
	if (eolexist == FALSE) {
		mlerase();
		TTflush();
	}

	movecursor(term.t_nrow, 0);
	va_start(ap, fmt);
	while ((c = *fmt++) != 0) {
		if (c != '%') {
			TTputc(c);
			++ttcol;
		} else {
			c = *fmt++;
			switch (c) {
			case 'd':
				mlputi(va_arg(ap, int), 10);
				break;

			case 'o':
				mlputi(va_arg(ap, int), 8);
				break;

			case 'x':
				mlputi(va_arg(ap, int), 16);
				break;

			case 'D':
				mlputli(va_arg(ap, long), 10);
				break;

			case 's':
				mlputs(va_arg(ap, char *));
				break;

			case 'f':
				mlputf(va_arg(ap, int));
				break;

			default:
				TTputc(c);
				++ttcol;
			}
		}
	}
	va_end(ap);

	/* if we can, erase to the end of screen */
	if (eolexist == TRUE)
		TTeeol();
	TTflush();
	mpresf = TRUE;
}

/*
 * Force a string out to the message line regardless of the
 * current $discmd setting. This is needed when $debug is TRUE
 * and for the write-message and clear-message-line commands
 *
 * char *s;		string to force out
 */
void mlforce(char *s)
{
	int oldcmd;	/* original command display flag */

	oldcmd = discmd;	/* save the discmd value */
	discmd = TRUE;		/* and turn display on */
	mlwrite(s);		/* write the string out */
	discmd = oldcmd;	/* and restore the original setting */
}

/*
 * Write out a string. Update the physical cursor position. This assumes that
 * the characters in the string all have width "1"; if this is not the case
 * things will get screwed up a little.
 */
void mlputs(char *s)
{
	int c;

	while ((c = *s++) != 0) {
		TTputc(c);
		++ttcol;
	}
}

/*
 * Write out an integer, in the specified radix. Update the physical cursor
 * position.
 */
static void mlputi(int i, int r)
{
	int q;
	static char hexdigits[] = "0123456789ABCDEF";

	if (i < 0) {
		i = -i;
		TTputc('-');
	}

	q = i / r;

	if (q != 0)
		mlputi(q, r);

	TTputc(hexdigits[i % r]);
	++ttcol;
}

/*
 * do the same except as a long integer.
 */
static void mlputli(long l, int r)
{
	long q;

	if (l < 0) {
		l = -l;
		TTputc('-');
	}

	q = l / r;

	if (q != 0)
		mlputli(q, r);

	TTputc((int) (l % r) + '0');
	++ttcol;
}

/*
 * write out a scaled integer with two decimal places
 *
 * int s;		scaled integer to output
 */
static void mlputf(int s)
{
	int i;			/* integer portion of number */
	int f;			/* fractional portion of number */

	/* break it up */
	i = s / 100;
	f = s % 100;

	/* send out the integer portion */
	mlputi(i, 10);
	TTputc('.');
	TTputc((f / 10) + '0');
	TTputc((f % 10) + '0');
	ttcol += 3;
}

#if RAINBOW

static void putline(int row, int col, char *buf)
{
	int n;

	n = strlen(buf);
	if (col + n - 1 > term.t_ncol)
		n = term.t_ncol - col + 1;
	Put_Data(row, col, n, buf);
}
#endif

/* Get terminal size from system.
   Store number of lines into *heightp and width into *widthp.
   If zero or a negative number is stored, the value is not valid.  */

void getscreensize(int *widthp, int *heightp)
{
#ifdef TIOCGWINSZ
	struct winsize size;
	*widthp = 0;
	*heightp = 0;
	if (ioctl(0, TIOCGWINSZ, &size) < 0)
		return;
	*widthp = size.ws_col;
	*heightp = size.ws_row;
#else
	*widthp = 0;
	*heightp = 0;
#endif
}

#ifdef SIGWINCH
void sizesignal(int signr)
{
	int w, h;
	int old_errno = errno;

	getscreensize(&w, &h);

	if (h && w && (h - 1 != term.t_nrow || w != term.t_ncol))
		newscreensize(h, w);

	signal(SIGWINCH, sizesignal);
	errno = old_errno;
}

static int newscreensize(int h, int w)
{
	/* do the change later */
	if (displaying) {
		chg_width = w;
		chg_height = h;
		return FALSE;
	}
	chg_width = chg_height = 0;
	if (h - 1 < term.t_mrow)
		newsize(TRUE, h);
	if (w < term.t_mcol)
		newwidth(TRUE, w);

	update(TRUE);
	return TRUE;
}

#endif