File: display.c

package info (click to toggle)
mg 20180927-1
  • links: PTS, VCS
  • area: main
  • in suites: bullseye, buster, sid
  • size: 696 kB
  • sloc: ansic: 14,387; makefile: 32; sh: 7
file content (1081 lines) | stat: -rw-r--r-- 26,841 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
/*	$OpenBSD: display.c,v 1.48 2017/07/06 19:27:37 schwarze 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 <sys/queue.h>
#include <ctype.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <term.h>

#include "def.h"
#include "kbd.h"

/*
 * 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.		 */
	int	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.
 */
struct score {
	int	s_itrace;	/* "i" index for track back.	 */
	int	s_jtrace;	/* "j" index for trace back.	 */
	int	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 *, int);
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] */

static int	 linenos = TRUE;
static int	 colnos = FALSE;

/* 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);
}

/* ARGSUSED */
int
colnotoggle(int f, int n)
{
	if (f & FFARG)
		colnos = n > 0;
	else
		colnos = !colnos;

	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)

#define TRYREALLOCARRAY(a, n, m) do {				\
		void *tmp;					\
		if ((tmp = reallocarray((a), (n), (m))) == 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;
			}
		}

		TRYREALLOCARRAY(score, newrow, newrow * sizeof(struct score));
		TRYREALLOCARRAY(vscreen, (newrow - 1), sizeof(struct video *));
		TRYREALLOCARRAY(pscreen, (newrow - 1), sizeof(struct video *));
		TRYREALLOCARRAY(video, (newrow - 1), 2 * 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);
		TRYREALLOC(blanks.v_text, newcol);
	}

	nrow = newrow;
	ncol = newcol;

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

	first_run = 0;
	return (TRUE);
}

#undef TRYREALLOC
#undef TRYREALLOCARRAY

/*
 * 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 (isprint(c)) {
		if (vtcol >= 0)
			vp->v_text[vtcol] = c;
		++vtcol;
	} else {
		char bf[5], *cp;

		snprintf(bf, sizeof(bf), "\\%o", c);
		for (cp = bf; *cp != '\0'; cp++)
			vtpute(*cp);
	}
}

/*
 * 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(int modelinecolor)
{
	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 || colnos) {
		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, modelinecolor);
		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;
		}
		ttcolor(CTEXT);
		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 modelinecolor)
{
	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 = modelinecolor;	/* 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 && colnos)
		len = snprintf(sl, sizeof(sl), "--L%d--C%d", wp->w_dotline,
		    getcolpos(wp));
	else if (linenos)
		len = snprintf(sl, sizeof(sl), "--L%d", wp->w_dotline);
	else if (colnos)
		len = snprintf(sl, sizeof(sl), "--C%d", getcolpos(wp));
	if ((linenos || colnos) && 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]);
}