xref: /freebsd/contrib/nvi/vi/vs_split.c (revision 39ee7a7a6bdd1557b1c3532abf60d139798ac88b)
1 /*-
2  * Copyright (c) 1993, 1994
3  *	The Regents of the University of California.  All rights reserved.
4  * Copyright (c) 1993, 1994, 1995, 1996
5  *	Keith Bostic.  All rights reserved.
6  *
7  * See the LICENSE file for redistribution information.
8  */
9 
10 #include "config.h"
11 
12 #ifndef lint
13 static const char sccsid[] = "$Id: vs_split.c,v 10.43 2015/04/05 15:21:55 zy Exp $";
14 #endif /* not lint */
15 
16 #include <sys/types.h>
17 #include <sys/queue.h>
18 #include <sys/time.h>
19 
20 #include <bitstring.h>
21 #include <errno.h>
22 #include <limits.h>
23 #include <stdio.h>
24 #include <stdlib.h>
25 #include <string.h>
26 
27 #include "../common/common.h"
28 #include "vi.h"
29 
30 typedef enum { HORIZ_FOLLOW, HORIZ_PRECEDE, VERT_FOLLOW, VERT_PRECEDE } jdir_t;
31 
32 static SCR	*vs_getbg(SCR *, char *);
33 static void      vs_insert(SCR *sp, GS *gp);
34 static int	 vs_join(SCR *, SCR **, jdir_t *);
35 
36 /*
37  * vs_split --
38  *	Create a new screen, horizontally.
39  *
40  * PUBLIC: int vs_split(SCR *, SCR *, int);
41  */
42 int
43 vs_split(
44 	SCR *sp,
45 	SCR *new,
46 	int ccl)		/* Colon-command line split. */
47 {
48 	GS *gp;
49 	SMAP *smp;
50 	size_t half;
51 	int issmallscreen, splitup;
52 
53 	gp = sp->gp;
54 
55 	/* Check to see if it's possible. */
56 	/* XXX: The IS_ONELINE fix will change this, too. */
57 	if (sp->rows < 4) {
58 		msgq(sp, M_ERR,
59 		    "222|Screen must be larger than %d lines to split", 4 - 1);
60 		return (1);
61 	}
62 
63 	/* Wait for any messages in the screen. */
64 	vs_resolve(sp, NULL, 1);
65 
66 	/* Get a new screen map. */
67 	CALLOC(sp, _HMAP(new), SMAP *, SIZE_HMAP(sp), sizeof(SMAP));
68 	if (_HMAP(new) == NULL)
69 		return (1);
70 	_HMAP(new)->lno = sp->lno;
71 	_HMAP(new)->coff = 0;
72 	_HMAP(new)->soff = 1;
73 
74 	/* Split the screen in half. */
75 	half = sp->rows / 2;
76 	if (ccl && half > 6)
77 		half = 6;
78 
79 	/*
80 	 * Small screens: see vs_refresh.c section 6a.  Set a flag so
81 	 * we know to fix the screen up later.
82 	 */
83 	issmallscreen = IS_SMALL(sp);
84 
85 	/* The columns in the screen don't change. */
86 	new->coff = sp->coff;
87 	new->cols = sp->cols;
88 
89 	/*
90 	 * Split the screen, and link the screens together.  If creating a
91 	 * screen to edit the colon command line or the cursor is in the top
92 	 * half of the current screen, the new screen goes under the current
93 	 * screen.  Else, it goes above the current screen.
94 	 *
95 	 * Recalculate current cursor position based on sp->lno, we're called
96 	 * with the cursor on the colon command line.  Then split the screen
97 	 * in half and update the shared information.
98 	 */
99 	splitup =
100 	    !ccl && (vs_sm_cursor(sp, &smp) ? 0 : (smp - HMAP) + 1) >= half;
101 	if (splitup) {				/* Old is bottom half. */
102 		new->rows = sp->rows - half;	/* New. */
103 		new->roff = sp->roff;
104 		sp->rows = half;		/* Old. */
105 		sp->roff += new->rows;
106 
107 		/*
108 		 * If the parent is the bottom half of the screen, shift
109 		 * the map down to match on-screen text.
110 		 */
111 		memcpy(_HMAP(sp), _HMAP(sp) + new->rows,
112 		    (sp->t_maxrows - new->rows) * sizeof(SMAP));
113 	} else {				/* Old is top half. */
114 		new->rows = half;		/* New. */
115 		sp->rows -= half;		/* Old. */
116 		new->roff = sp->roff + sp->rows;
117 	}
118 
119 	/* Adjust maximum text count. */
120 	sp->t_maxrows = IS_ONELINE(sp) ? 1 : sp->rows - 1;
121 	new->t_maxrows = IS_ONELINE(new) ? 1 : new->rows - 1;
122 
123 	/*
124 	 * Small screens: see vs_refresh.c, section 6a.
125 	 *
126 	 * The child may have different screen options sizes than the parent,
127 	 * so use them.  Guarantee that text counts aren't larger than the
128 	 * new screen sizes.
129 	 */
130 	if (issmallscreen) {
131 		/* Fix the text line count for the parent. */
132 		if (splitup)
133 			sp->t_rows -= new->rows;
134 
135 		/* Fix the parent screen. */
136 		if (sp->t_rows > sp->t_maxrows)
137 			sp->t_rows = sp->t_maxrows;
138 		if (sp->t_minrows > sp->t_maxrows)
139 			sp->t_minrows = sp->t_maxrows;
140 
141 		/* Fix the child screen. */
142 		new->t_minrows = new->t_rows = O_VAL(sp, O_WINDOW);
143 		if (new->t_rows > new->t_maxrows)
144 			new->t_rows = new->t_maxrows;
145 		if (new->t_minrows > new->t_maxrows)
146 			new->t_minrows = new->t_maxrows;
147 	} else {
148 		sp->t_minrows = sp->t_rows = IS_ONELINE(sp) ? 1 : sp->rows - 1;
149 
150 		/*
151 		 * The new screen may be a small screen, even if the parent
152 		 * was not.  Don't complain if O_WINDOW is too large, we're
153 		 * splitting the screen so the screen is much smaller than
154 		 * normal.
155 		 */
156 		new->t_minrows = new->t_rows = O_VAL(sp, O_WINDOW);
157 		if (new->t_rows > new->rows - 1)
158 			new->t_minrows = new->t_rows =
159 			    IS_ONELINE(new) ? 1 : new->rows - 1;
160 	}
161 
162 	/* Adjust the ends of the new and old maps. */
163 	_TMAP(sp) = IS_ONELINE(sp) ?
164 	    _HMAP(sp) : _HMAP(sp) + (sp->t_rows - 1);
165 	_TMAP(new) = IS_ONELINE(new) ?
166 	    _HMAP(new) : _HMAP(new) + (new->t_rows - 1);
167 
168 	/* Reset the length of the default scroll. */
169 	if ((sp->defscroll = sp->t_maxrows / 2) == 0)
170 		sp->defscroll = 1;
171 	if ((new->defscroll = new->t_maxrows / 2) == 0)
172 		new->defscroll = 1;
173 
174 	/* Fit the screen into the logical chain. */
175 	vs_insert(new, sp->gp);
176 
177 	/* Tell the display that we're splitting. */
178 	(void)gp->scr_split(sp, new);
179 
180 	/*
181 	 * Initialize the screen flags:
182 	 *
183 	 * If we're in vi mode in one screen, we don't have to reinitialize.
184 	 * This isn't just a cosmetic fix.  The path goes like this:
185 	 *
186 	 *	return into vi(), SC_SSWITCH set
187 	 *	call vs_refresh() with SC_STATUS set
188 	 *	call vs_resolve to display the status message
189 	 *	call vs_refresh() because the SC_SCR_VI bit isn't set
190 	 *
191 	 * Things go downhill at this point.
192 	 *
193 	 * Draw the new screen from scratch, and add a status line.
194 	 */
195 	F_SET(new,
196 	    SC_SCR_REFORMAT | SC_STATUS |
197 	    F_ISSET(sp, SC_EX | SC_VI | SC_SCR_VI | SC_SCR_EX | SC_READONLY));
198 	return (0);
199 }
200 
201 /*
202  * vs_vsplit --
203  *	Create a new screen, vertically.
204  *
205  * PUBLIC: int vs_vsplit(SCR *, SCR *);
206  */
207 int
208 vs_vsplit(SCR *sp, SCR *new)
209 {
210 	GS *gp;
211 	size_t cols;
212 
213 	gp = sp->gp;
214 
215 	/* Check to see if it's possible. */
216 	if (sp->cols / 2 <= MINIMUM_SCREEN_COLS) {
217 		msgq(sp, M_ERR,
218 		    "288|Screen must be larger than %d columns to split",
219 		    MINIMUM_SCREEN_COLS * 2);
220 		return (1);
221 	}
222 
223 	/* Wait for any messages in the screen. */
224 	vs_resolve(sp, NULL, 1);
225 
226 	/* Get a new screen map. */
227 	CALLOC(sp, _HMAP(new), SMAP *, SIZE_HMAP(sp), sizeof(SMAP));
228 	if (_HMAP(new) == NULL)
229 		return (1);
230 	_HMAP(new)->lno = sp->lno;
231 	_HMAP(new)->coff = 0;
232 	_HMAP(new)->soff = 1;
233 
234 	/*
235 	 * Split the screen in half; we have to sacrifice a column to delimit
236 	 * the screens.
237 	 *
238 	 * XXX
239 	 * We always split to the right... that makes more sense to me, and
240 	 * I don't want to play the stupid games that I play when splitting
241 	 * horizontally.
242 	 *
243 	 * XXX
244 	 * We reserve a column for the screen, "knowing" that curses needs
245 	 * one.  This should be worked out with the display interface.
246 	 */
247 	cols = sp->cols / 2;
248 	new->cols = sp->cols - cols - 1;
249 	sp->cols = cols;
250 	new->coff = sp->coff + cols + 1;
251 	sp->cno = 0;
252 
253 	/* Nothing else changes. */
254 	new->rows = sp->rows;
255 	new->t_rows = sp->t_rows;
256 	new->t_maxrows = sp->t_maxrows;
257 	new->t_minrows = sp->t_minrows;
258 	new->roff = sp->roff;
259 	new->defscroll = sp->defscroll;
260 	_TMAP(new) = _HMAP(new) + (new->t_rows - 1);
261 
262 	/* Fit the screen into the logical chain. */
263 	vs_insert(new, sp->gp);
264 
265 	/* Tell the display that we're splitting. */
266 	(void)gp->scr_split(sp, new);
267 
268 	/* Redraw the old screen from scratch. */
269 	F_SET(sp, SC_SCR_REFORMAT | SC_STATUS);
270 
271 	/*
272 	 * Initialize the screen flags:
273 	 *
274 	 * If we're in vi mode in one screen, we don't have to reinitialize.
275 	 * This isn't just a cosmetic fix.  The path goes like this:
276 	 *
277 	 *	return into vi(), SC_SSWITCH set
278 	 *	call vs_refresh() with SC_STATUS set
279 	 *	call vs_resolve to display the status message
280 	 *	call vs_refresh() because the SC_SCR_VI bit isn't set
281 	 *
282 	 * Things go downhill at this point.
283 	 *
284 	 * Draw the new screen from scratch, and add a status line.
285 	 */
286 	F_SET(new,
287 	    SC_SCR_REFORMAT | SC_STATUS |
288 	    F_ISSET(sp, SC_EX | SC_VI | SC_SCR_VI | SC_SCR_EX | SC_READONLY));
289 	return (0);
290 }
291 
292 /*
293  * vs_insert --
294  *	Insert the new screen into the correct place in the logical
295  *	chain.
296  */
297 static void
298 vs_insert(SCR *sp, GS *gp)
299 {
300 	SCR *tsp;
301 
302 	gp = sp->gp;
303 
304 	/* Move past all screens with lower row numbers. */
305 	TAILQ_FOREACH(tsp, gp->dq, q)
306 		if (tsp->roff >= sp->roff)
307 			break;
308 	/*
309 	 * Move past all screens with the same row number and lower
310 	 * column numbers.
311 	 */
312 	for (; tsp != NULL; tsp = TAILQ_NEXT(tsp, q))
313 		if (tsp->roff != sp->roff || tsp->coff > sp->coff)
314 			break;
315 
316 	/*
317 	 * If we reached the end, this screen goes there.  Otherwise,
318 	 * put it before or after the screen where we stopped.
319 	 */
320 	if (tsp == NULL) {
321 		TAILQ_INSERT_TAIL(gp->dq, sp, q);
322 	} else if (tsp->roff < sp->roff ||
323 	    (tsp->roff == sp->roff && tsp->coff < sp->coff)) {
324 		TAILQ_INSERT_AFTER(gp->dq, tsp, sp, q);
325 	} else
326 		TAILQ_INSERT_BEFORE(tsp, sp, q);
327 }
328 
329 /*
330  * vs_discard --
331  *	Discard the screen, folding the real-estate into a related screen,
332  *	if one exists, and return that screen.
333  *
334  * PUBLIC: int vs_discard(SCR *, SCR **);
335  */
336 int
337 vs_discard(SCR *sp, SCR **spp)
338 {
339 	GS *gp;
340 	SCR *tsp, **lp, *list[100];
341 	jdir_t jdir;
342 
343 	gp = sp->gp;
344 
345 	/*
346 	 * Save the old screen's cursor information.
347 	 *
348 	 * XXX
349 	 * If called after file_end(), and the underlying file was a tmp
350 	 * file, it may have gone away.
351 	 */
352 	if (sp->frp != NULL) {
353 		sp->frp->lno = sp->lno;
354 		sp->frp->cno = sp->cno;
355 		F_SET(sp->frp, FR_CURSORSET);
356 	}
357 
358 	/* If no other screens to join, we're done. */
359 	if (!IS_SPLIT(sp)) {
360 		(void)gp->scr_discard(sp, NULL);
361 
362 		if (spp != NULL)
363 			*spp = NULL;
364 		return (0);
365 	}
366 
367 	/*
368 	 * Find a set of screens that cover one of the screen's borders.
369 	 * Check the vertical axis first, for no particular reason.
370 	 *
371 	 * XXX
372 	 * It's possible (I think?), to create a screen that shares no full
373 	 * border with any other set of screens, so we can't discard it.  We
374 	 * just complain at the user until they clean it up.
375 	 */
376 	if (vs_join(sp, list, &jdir))
377 		return (1);
378 
379 	/*
380 	 * Modify the affected screens.  Redraw the modified screen(s) from
381 	 * scratch, setting a status line.  If this is ever a performance
382 	 * problem we could play games with the map, but I wrote that code
383 	 * before and it was never clean or easy.
384 	 *
385 	 * Don't clean up the discarded screen's information.  If the screen
386 	 * isn't exiting, we'll do the work when the user redisplays it.
387 	 */
388 	switch (jdir) {
389 	case HORIZ_FOLLOW:
390 	case HORIZ_PRECEDE:
391 		for (lp = &list[0]; (tsp = *lp) != NULL; ++lp) {
392 			/*
393 			 * Small screens: see vs_refresh.c section 6a.  Adjust
394 			 * text line info, unless it's a small screen.
395 			 *
396 			 * Reset the length of the default scroll.
397 			 *
398 			 * Reset the map references.
399 			 */
400 			tsp->rows += sp->rows;
401 			if (!IS_SMALL(tsp))
402 				tsp->t_rows = tsp->t_minrows = tsp->rows - 1;
403 			tsp->t_maxrows = tsp->rows - 1;
404 
405 			tsp->defscroll = tsp->t_maxrows / 2;
406 
407 			*(_HMAP(tsp) + (tsp->t_rows - 1)) = *_TMAP(tsp);
408 			_TMAP(tsp) = _HMAP(tsp) + (tsp->t_rows - 1);
409 
410 			switch (jdir) {
411 			case HORIZ_FOLLOW:
412 				tsp->roff = sp->roff;
413 				vs_sm_fill(tsp, OOBLNO, P_TOP);
414 				break;
415 			case HORIZ_PRECEDE:
416 				vs_sm_fill(tsp, OOBLNO, P_BOTTOM);
417 				break;
418 			default:
419 				abort();
420 			}
421 			F_SET(tsp, SC_STATUS);
422 		}
423 		break;
424 	case VERT_FOLLOW:
425 	case VERT_PRECEDE:
426 		for (lp = &list[0]; (tsp = *lp) != NULL; ++lp) {
427 			if (jdir == VERT_FOLLOW)
428 				tsp->coff = sp->coff;
429 			tsp->cols += sp->cols + 1;	/* XXX: DIVIDER */
430 			vs_sm_fill(tsp, OOBLNO, P_TOP);
431 			F_SET(tsp, SC_STATUS);
432 		}
433 		break;
434 	default:
435 		abort();
436 	}
437 
438 	/* Find the closest screen that changed and move to it. */
439 	tsp = list[0];
440 	if (spp != NULL)
441 		*spp = tsp;
442 
443 	/* Tell the display that we're discarding a screen. */
444 	(void)gp->scr_discard(sp, list);
445 
446 	return (0);
447 }
448 
449 /*
450  * vs_join --
451  *	Find a set of screens that covers a screen's border.
452  */
453 static int
454 vs_join(SCR *sp, SCR **listp, jdir_t *jdirp)
455 {
456 	GS *gp;
457 	SCR **lp, *tsp;
458 	int first;
459 	size_t tlen;
460 
461 	gp = sp->gp;
462 
463 	/* Check preceding vertical. */
464 	for (lp = listp, tlen = sp->rows,
465 	    tsp = TAILQ_FIRST(gp->dq);
466 	    tsp != NULL; tsp = TAILQ_NEXT(tsp, q)) {
467 		if (sp == tsp)
468 			continue;
469 		/* Test if precedes the screen vertically. */
470 		if (tsp->coff + tsp->cols + 1 != sp->coff)
471 			continue;
472 		/*
473 		 * Test if a subset on the vertical axis.  If overlaps the
474 		 * beginning or end, we can't join on this axis at all.
475 		 */
476 		if (tsp->roff > sp->roff + sp->rows)
477 			continue;
478 		if (tsp->roff < sp->roff) {
479 			if (tsp->roff + tsp->rows >= sp->roff)
480 				break;
481 			continue;
482 		}
483 		if (tsp->roff + tsp->rows > sp->roff + sp->rows)
484 			break;
485 #ifdef DEBUG
486 		if (tlen < tsp->rows)
487 			abort();
488 #endif
489 		tlen -= tsp->rows;
490 		*lp++ = tsp;
491 	}
492 	if (tlen == 0) {
493 		*lp = NULL;
494 		*jdirp = VERT_PRECEDE;
495 		return (0);
496 	}
497 
498 	/* Check following vertical. */
499 	for (lp = listp, tlen = sp->rows,
500 	    tsp = TAILQ_FIRST(gp->dq);
501 	    tsp != NULL; tsp = TAILQ_NEXT(tsp, q)) {
502 		if (sp == tsp)
503 			continue;
504 		/* Test if follows the screen vertically. */
505 		if (tsp->coff != sp->coff + sp->cols + 1)
506 			continue;
507 		/*
508 		 * Test if a subset on the vertical axis.  If overlaps the
509 		 * beginning or end, we can't join on this axis at all.
510 		 */
511 		if (tsp->roff > sp->roff + sp->rows)
512 			continue;
513 		if (tsp->roff < sp->roff) {
514 			if (tsp->roff + tsp->rows >= sp->roff)
515 				break;
516 			continue;
517 		}
518 		if (tsp->roff + tsp->rows > sp->roff + sp->rows)
519 			break;
520 #ifdef DEBUG
521 		if (tlen < tsp->rows)
522 			abort();
523 #endif
524 		tlen -= tsp->rows;
525 		*lp++ = tsp;
526 	}
527 	if (tlen == 0) {
528 		*lp = NULL;
529 		*jdirp = VERT_FOLLOW;
530 		return (0);
531 	}
532 
533 	/* Check preceding horizontal. */
534 	for (first = 0, lp = listp, tlen = sp->cols,
535 	    tsp = TAILQ_FIRST(gp->dq);
536 	    tsp != NULL; tsp = TAILQ_NEXT(tsp, q)) {
537 		if (sp == tsp)
538 			continue;
539 		/* Test if precedes the screen horizontally. */
540 		if (tsp->roff + tsp->rows != sp->roff)
541 			continue;
542 		/*
543 		 * Test if a subset on the horizontal axis.  If overlaps the
544 		 * beginning or end, we can't join on this axis at all.
545 		 */
546 		if (tsp->coff > sp->coff + sp->cols)
547 			continue;
548 		if (tsp->coff < sp->coff) {
549 			if (tsp->coff + tsp->cols >= sp->coff)
550 				break;
551 			continue;
552 		}
553 		if (tsp->coff + tsp->cols > sp->coff + sp->cols)
554 			break;
555 #ifdef DEBUG
556 		if (tlen < tsp->cols)
557 			abort();
558 #endif
559 		tlen -= tsp->cols + first;
560 		first = 1;
561 		*lp++ = tsp;
562 	}
563 	if (tlen == 0) {
564 		*lp = NULL;
565 		*jdirp = HORIZ_PRECEDE;
566 		return (0);
567 	}
568 
569 	/* Check following horizontal. */
570 	for (first = 0, lp = listp, tlen = sp->cols,
571 	    tsp = TAILQ_FIRST(gp->dq);
572 	    tsp != NULL; tsp = TAILQ_NEXT(tsp, q)) {
573 		if (sp == tsp)
574 			continue;
575 		/* Test if precedes the screen horizontally. */
576 		if (tsp->roff != sp->roff + sp->rows)
577 			continue;
578 		/*
579 		 * Test if a subset on the horizontal axis.  If overlaps the
580 		 * beginning or end, we can't join on this axis at all.
581 		 */
582 		if (tsp->coff > sp->coff + sp->cols)
583 			continue;
584 		if (tsp->coff < sp->coff) {
585 			if (tsp->coff + tsp->cols >= sp->coff)
586 				break;
587 			continue;
588 		}
589 		if (tsp->coff + tsp->cols > sp->coff + sp->cols)
590 			break;
591 #ifdef DEBUG
592 		if (tlen < tsp->cols)
593 			abort();
594 #endif
595 		tlen -= tsp->cols + first;
596 		first = 1;
597 		*lp++ = tsp;
598 	}
599 	if (tlen == 0) {
600 		*lp = NULL;
601 		*jdirp = HORIZ_FOLLOW;
602 		return (0);
603 	}
604 	return (1);
605 }
606 
607 /*
608  * vs_fg --
609  *	Background the current screen, and foreground a new one.
610  *
611  * PUBLIC: int vs_fg(SCR *, SCR **, CHAR_T *, int);
612  */
613 int
614 vs_fg(SCR *sp, SCR **nspp, CHAR_T *name, int newscreen)
615 {
616 	GS *gp;
617 	SCR *nsp;
618 	char *np;
619 	size_t nlen;
620 
621 	gp = sp->gp;
622 
623 	if (name)
624 	    INT2CHAR(sp, name, STRLEN(name) + 1, np, nlen);
625 	else
626 	    np = NULL;
627 	if (newscreen)
628 		/* Get the specified background screen. */
629 		nsp = vs_getbg(sp, np);
630 	else
631 		/* Swap screens. */
632 		if (vs_swap(sp, &nsp, np))
633 			return (1);
634 
635 	if ((*nspp = nsp) == NULL) {
636 		msgq_wstr(sp, M_ERR, name,
637 		    name == NULL ?
638 		    "223|There are no background screens" :
639 		    "224|There's no background screen editing a file named %s");
640 		return (1);
641 	}
642 
643 	if (newscreen) {
644 		/* Remove the new screen from the background queue. */
645 		TAILQ_REMOVE(gp->hq, nsp, q);
646 
647 		/* Split the screen; if we fail, hook the screen back in. */
648 		if (vs_split(sp, nsp, 0)) {
649 			TAILQ_INSERT_TAIL(gp->hq, nsp, q);
650 			return (1);
651 		}
652 	} else {
653 		/* Move the old screen to the background queue. */
654 		TAILQ_REMOVE(gp->dq, sp, q);
655 		TAILQ_INSERT_TAIL(gp->hq, sp, q);
656 	}
657 	return (0);
658 }
659 
660 /*
661  * vs_bg --
662  *	Background the screen, and switch to the next one.
663  *
664  * PUBLIC: int vs_bg(SCR *);
665  */
666 int
667 vs_bg(SCR *sp)
668 {
669 	GS *gp;
670 	SCR *nsp;
671 
672 	gp = sp->gp;
673 
674 	/* Try and join with another screen. */
675 	if (vs_discard(sp, &nsp))
676 		return (1);
677 	if (nsp == NULL) {
678 		msgq(sp, M_ERR,
679 		    "225|You may not background your only displayed screen");
680 		return (1);
681 	}
682 
683 	/* Move the old screen to the background queue. */
684 	TAILQ_REMOVE(gp->dq, sp, q);
685 	TAILQ_INSERT_TAIL(gp->hq, sp, q);
686 
687 	/* Toss the screen map. */
688 	free(_HMAP(sp));
689 	_HMAP(sp) = NULL;
690 
691 	/* Switch screens. */
692 	sp->nextdisp = nsp;
693 	F_SET(sp, SC_SSWITCH);
694 
695 	return (0);
696 }
697 
698 /*
699  * vs_swap --
700  *	Swap the current screen with a backgrounded one.
701  *
702  * PUBLIC: int vs_swap(SCR *, SCR **, char *);
703  */
704 int
705 vs_swap(SCR *sp, SCR **nspp, char *name)
706 {
707 	GS *gp;
708 	SCR *nsp, *list[2];
709 
710 	gp = sp->gp;
711 
712 	/* Get the specified background screen. */
713 	if ((*nspp = nsp = vs_getbg(sp, name)) == NULL)
714 		return (0);
715 
716 	/*
717 	 * Save the old screen's cursor information.
718 	 *
719 	 * XXX
720 	 * If called after file_end(), and the underlying file was a tmp
721 	 * file, it may have gone away.
722 	 */
723 	if (sp->frp != NULL) {
724 		sp->frp->lno = sp->lno;
725 		sp->frp->cno = sp->cno;
726 		F_SET(sp->frp, FR_CURSORSET);
727 	}
728 
729 	/* Switch screens. */
730 	sp->nextdisp = nsp;
731 	F_SET(sp, SC_SSWITCH);
732 
733 	/* Initialize terminal information. */
734 	VIP(nsp)->srows = VIP(sp)->srows;
735 
736 	/* Initialize screen information. */
737 	nsp->cols = sp->cols;
738 	nsp->rows = sp->rows;	/* XXX: Only place in vi that sets rows. */
739 	nsp->roff = sp->roff;
740 
741 	/*
742 	 * Small screens: see vs_refresh.c, section 6a.
743 	 *
744 	 * The new screens may have different screen options sizes than the
745 	 * old one, so use them.  Make sure that text counts aren't larger
746 	 * than the new screen sizes.
747 	 */
748 	if (IS_SMALL(nsp)) {
749 		nsp->t_minrows = nsp->t_rows = O_VAL(nsp, O_WINDOW);
750 		if (nsp->t_rows > sp->t_maxrows)
751 			nsp->t_rows = nsp->t_maxrows;
752 		if (nsp->t_minrows > sp->t_maxrows)
753 			nsp->t_minrows = nsp->t_maxrows;
754 	} else
755 		nsp->t_rows = nsp->t_maxrows = nsp->t_minrows = nsp->rows - 1;
756 
757 	/* Reset the length of the default scroll. */
758 	nsp->defscroll = nsp->t_maxrows / 2;
759 
760 	/* Allocate a new screen map. */
761 	CALLOC_RET(nsp, _HMAP(nsp), SMAP *, SIZE_HMAP(nsp), sizeof(SMAP));
762 	_TMAP(nsp) = _HMAP(nsp) + (nsp->t_rows - 1);
763 
764 	/* Fill the map. */
765 	nsp->gp = sp->gp;
766 	if (vs_sm_fill(nsp, nsp->lno, P_FILL))
767 		return (1);
768 
769 	/*
770 	 * The new screen replaces the old screen in the parent/child list.
771 	 * We insert the new screen after the old one.  If we're exiting,
772 	 * the exit will delete the old one, if we're foregrounding, the fg
773 	 * code will move the old one to the background queue.
774 	 */
775 	TAILQ_REMOVE(gp->hq, nsp, q);
776 	TAILQ_INSERT_AFTER(gp->dq, sp, nsp, q);
777 
778 	/*
779 	 * Don't change the screen's cursor information other than to
780 	 * note that the cursor is wrong.
781 	 */
782 	F_SET(VIP(nsp), VIP_CUR_INVALID);
783 
784 	/* Draw the new screen from scratch, and add a status line. */
785 	F_SET(nsp, SC_SCR_REDRAW | SC_STATUS);
786 
787 	list[0] = nsp; list[1] = NULL;
788 	(void)gp->scr_discard(sp, list);
789 
790 	return (0);
791 }
792 
793 /*
794  * vs_resize --
795  *	Change the absolute size of the current screen.
796  *
797  * PUBLIC: int vs_resize(SCR *, long, adj_t);
798  */
799 int
800 vs_resize(SCR *sp, long int count, adj_t adj)
801 {
802 	GS *gp;
803 	SCR *g, *s, *prev, *next, *list[3] = {NULL, NULL, NULL};
804 	size_t g_off, s_off;
805 
806 	gp = sp->gp;
807 
808 	/*
809 	 * Figure out which screens will grow, which will shrink, and
810 	 * make sure it's possible.
811 	 */
812 	if (count == 0)
813 		return (0);
814 	if (adj == A_SET) {
815 		if (sp->t_maxrows == count)
816 			return (0);
817 		if (sp->t_maxrows > count) {
818 			adj = A_DECREASE;
819 			count = sp->t_maxrows - count;
820 		} else {
821 			adj = A_INCREASE;
822 			count = count - sp->t_maxrows;
823 		}
824 	}
825 
826 	/* Find first overlapping screen */
827 	for (next = TAILQ_NEXT(sp, q); next != NULL &&
828 	     (next->coff >= sp->coff + sp->cols ||
829 	      next->coff + next->cols <= sp->coff);
830 	     next = TAILQ_NEXT(next, q));
831 	/* See if we can use it */
832 	if (next != NULL &&
833 	    (sp->coff != next->coff || sp->cols != next->cols))
834 		next = NULL;
835 	for (prev = TAILQ_PREV(sp, _dqh, q); prev != NULL &&
836 	     (prev->coff >= sp->coff + sp->cols ||
837 	      prev->coff + prev->cols <= sp->coff);
838 	     prev = TAILQ_PREV(prev, _dqh, q));
839 	if (prev != NULL &&
840 	    (sp->coff != prev->coff || sp->cols != prev->cols))
841 		prev = NULL;
842 
843 	g_off = s_off = 0;
844 	if (adj == A_DECREASE) {
845 		if (count < 0)
846 			count = -count;
847 		s = sp;
848 		if (s->t_maxrows < MINIMUM_SCREEN_ROWS + count)
849 			goto toosmall;
850 		if ((g = prev) == NULL) {
851 			if ((g = next) == NULL)
852 				goto toobig;
853 			g_off = -count;
854 		} else
855 			s_off = count;
856 	} else {
857 		g = sp;
858 		if ((s = next) != NULL &&
859 		    s->t_maxrows >= MINIMUM_SCREEN_ROWS + count)
860 				s_off = count;
861 		else
862 			s = NULL;
863 		if (s == NULL) {
864 			if ((s = prev) == NULL) {
865 toobig:				msgq(sp, M_BERR, adj == A_DECREASE ?
866 				    "227|The screen cannot shrink" :
867 				    "228|The screen cannot grow");
868 				return (1);
869 			}
870 			if (s->t_maxrows < MINIMUM_SCREEN_ROWS + count) {
871 toosmall:			msgq(sp, M_BERR,
872 				    "226|The screen can only shrink to %d rows",
873 				    MINIMUM_SCREEN_ROWS);
874 				return (1);
875 			}
876 			g_off = -count;
877 		}
878 	}
879 
880 	/*
881 	 * Fix up the screens; we could optimize the reformatting of the
882 	 * screen, but this isn't likely to be a common enough operation
883 	 * to make it worthwhile.
884 	 */
885 	s->rows += -count;
886 	s->roff += s_off;
887 	g->rows += count;
888 	g->roff += g_off;
889 
890 	g->t_rows += count;
891 	if (g->t_minrows == g->t_maxrows)
892 		g->t_minrows += count;
893 	g->t_maxrows += count;
894 	_TMAP(g) += count;
895 	F_SET(g, SC_SCR_REFORMAT | SC_STATUS);
896 
897 	s->t_rows -= count;
898 	s->t_maxrows -= count;
899 	if (s->t_minrows > s->t_maxrows)
900 		s->t_minrows = s->t_maxrows;
901 	_TMAP(s) -= count;
902 	F_SET(s, SC_SCR_REFORMAT | SC_STATUS);
903 
904 	/* XXXX */
905 	list[0] = g; list[1] = s;
906 	gp->scr_discard(0, list);
907 
908 	return (0);
909 }
910 
911 /*
912  * vs_getbg --
913  *	Get the specified background screen, or, if name is NULL, the first
914  *	background screen.
915  */
916 static SCR *
917 vs_getbg(SCR *sp, char *name)
918 {
919 	GS *gp;
920 	SCR *nsp;
921 	char *p;
922 
923 	gp = sp->gp;
924 
925 	/* If name is NULL, return the first background screen on the list. */
926 	if (name == NULL)
927 		return (TAILQ_FIRST(gp->hq));
928 
929 	/* Search for a full match. */
930 	TAILQ_FOREACH(nsp, gp->hq, q)
931 		if (!strcmp(nsp->frp->name, name))
932 			break;
933 	if (nsp != NULL)
934 		return (nsp);
935 
936 	/* Search for a last-component match. */
937 	TAILQ_FOREACH(nsp, gp->hq, q) {
938 		if ((p = strrchr(nsp->frp->name, '/')) == NULL)
939 			p = nsp->frp->name;
940 		else
941 			++p;
942 		if (!strcmp(p, name))
943 			break;
944 	}
945 	if (nsp != NULL)
946 		return (nsp);
947 
948 	return (NULL);
949 }
950