xref: /openbsd-src/lib/libcurses/tty/lib_mvcur.c (revision a28daedfc357b214be5c701aa8ba8adb29a7f1c2)
1 /*	$OpenBSD: lib_mvcur.c,v 1.12 2007/05/17 04:34:50 ray Exp $	*/
2 
3 /****************************************************************************
4  * Copyright (c) 1998,1999,2000 Free Software Foundation, Inc.              *
5  *                                                                          *
6  * Permission is hereby granted, free of charge, to any person obtaining a  *
7  * copy of this software and associated documentation files (the            *
8  * "Software"), to deal in the Software without restriction, including      *
9  * without limitation the rights to use, copy, modify, merge, publish,      *
10  * distribute, distribute with modifications, sublicense, and/or sell       *
11  * copies of the Software, and to permit persons to whom the Software is    *
12  * furnished to do so, subject to the following conditions:                 *
13  *                                                                          *
14  * The above copyright notice and this permission notice shall be included  *
15  * in all copies or substantial portions of the Software.                   *
16  *                                                                          *
17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS  *
18  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF               *
19  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.   *
20  * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,   *
21  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR    *
22  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR    *
23  * THE USE OR OTHER DEALINGS IN THE SOFTWARE.                               *
24  *                                                                          *
25  * Except as contained in this notice, the name(s) of the above copyright   *
26  * holders shall not be used in advertising or otherwise to promote the     *
27  * sale, use or other dealings in this Software without prior written       *
28  * authorization.                                                           *
29  ****************************************************************************/
30 
31 /****************************************************************************
32  *  Author: Zeyd M. Ben-Halim <zmbenhal@netcom.com> 1992,1995               *
33  *     and: Eric S. Raymond <esr@snark.thyrsus.com>                         *
34  ****************************************************************************/
35 
36 /*
37 **	lib_mvcur.c
38 **
39 **	The routines for moving the physical cursor and scrolling:
40 **
41 **		void _nc_mvcur_init(void)
42 **
43 **		void _nc_mvcur_resume(void)
44 **
45 **		int mvcur(int old_y, int old_x, int new_y, int new_x)
46 **
47 **		void _nc_mvcur_wrap(void)
48 **
49 ** Comparisons with older movement optimizers:
50 **    SVr3 curses mvcur() can't use cursor_to_ll or auto_left_margin.
51 **    4.4BSD curses can't use cuu/cud/cuf/cub/hpa/vpa/tab/cbt for local
52 ** motions.  It doesn't use tactics based on auto_left_margin.  Weirdly
53 ** enough, it doesn't use its own hardware-scrolling routine to scroll up
54 ** destination lines for out-of-bounds addresses!
55 **    old ncurses optimizer: less accurate cost computations (in fact,
56 ** it was broken and had to be commented out!).
57 **
58 ** Compile with -DMAIN to build an interactive tester/timer for the movement
59 ** optimizer.  You can use it to investigate the optimizer's behavior.
60 ** You can also use it for tuning the formulas used to determine whether
61 ** or not full optimization is attempted.
62 **
63 ** This code has a nasty tendency to find bugs in terminfo entries, because it
64 ** exercises the non-cup movement capabilities heavily.  If you think you've
65 ** found a bug, try deleting subsets of the following capabilities (arranged
66 ** in decreasing order of suspiciousness): it, tab, cbt, hpa, vpa, cuu, cud,
67 ** cuf, cub, cuu1, cud1, cuf1, cub1.  It may be that one or more are wrong.
68 **
69 ** Note: you should expect this code to look like a resource hog in a profile.
70 ** That's because it does a lot of I/O, through the tputs() calls.  The I/O
71 ** cost swamps the computation overhead (and as machines get faster, this
72 ** will become even more true).  Comments in the test exerciser at the end
73 ** go into detail about tuning and how you can gauge the optimizer's
74 ** effectiveness.
75 **/
76 
77 /****************************************************************************
78  *
79  * Constants and macros for optimizer tuning.
80  *
81  ****************************************************************************/
82 
83 /*
84  * The average overhead of a full optimization computation in character
85  * transmission times.  If it's too high, the algorithm will be a bit
86  * over-biased toward using cup rather than local motions; if it's too
87  * low, the algorithm may spend more time than is strictly optimal
88  * looking for non-cup motions.  Profile the optimizer using the `t'
89  * command of the exerciser (see below), and round to the nearest integer.
90  *
91  * Yes, I (esr) thought about computing expected overhead dynamically, say
92  * by derivation from a running average of optimizer times.  But the
93  * whole point of this optimization is to *decrease* the frequency of
94  * system calls. :-)
95  */
96 #define COMPUTE_OVERHEAD	1	/* I use a 90MHz Pentium @ 9.6Kbps */
97 
98 /*
99  * LONG_DIST is the distance we consider to be just as costly to move over as a
100  * cup sequence is to emit.  In other words, it's the length of a cup sequence
101  * adjusted for average computation overhead.  The magic number is the length
102  * of "\033[yy;xxH", the typical cup sequence these days.
103  */
104 #define LONG_DIST		(8 - COMPUTE_OVERHEAD)
105 
106 /*
107  * Tell whether a motion is optimizable by local motions.  Needs to be cheap to
108  * compute. In general, all the fast moves go to either the right or left edge
109  * of the screen.  So any motion to a location that is (a) further away than
110  * LONG_DIST and (b) further inward from the right or left edge than LONG_DIST,
111  * we'll consider nonlocal.
112  */
113 #define NOT_LOCAL(fy, fx, ty, tx)	((tx > LONG_DIST) && (tx < screen_lines - 1 - LONG_DIST) && (abs(ty-fy) + abs(tx-fx) > LONG_DIST))
114 
115 /****************************************************************************
116  *
117  * External interfaces
118  *
119  ****************************************************************************/
120 
121 /*
122  * For this code to work OK, the following components must live in the
123  * screen structure:
124  *
125  *	int		_char_padding;	// cost of character put
126  *	int		_cr_cost;	// cost of (carriage_return)
127  *	int		_cup_cost;	// cost of (cursor_address)
128  *	int		_home_cost;	// cost of (cursor_home)
129  *	int		_ll_cost;	// cost of (cursor_to_ll)
130  *#if USE_HARD_TABS
131  *	int		_ht_cost;	// cost of (tab)
132  *	int		_cbt_cost;	// cost of (back_tab)
133  *#endif USE_HARD_TABS
134  *	int		_cub1_cost;	// cost of (cursor_left)
135  *	int		_cuf1_cost;	// cost of (cursor_right)
136  *	int		_cud1_cost;	// cost of (cursor_down)
137  *	int		_cuu1_cost;	// cost of (cursor_up)
138  *	int		_cub_cost;	// cost of (parm_cursor_left)
139  *	int		_cuf_cost;	// cost of (parm_cursor_right)
140  *	int		_cud_cost;	// cost of (parm_cursor_down)
141  *	int		_cuu_cost;	// cost of (parm_cursor_up)
142  *	int		_hpa_cost;	// cost of (column_address)
143  *	int		_vpa_cost;	// cost of (row_address)
144  *	int		_ech_cost;	// cost of (erase_chars)
145  *	int		_rep_cost;	// cost of (repeat_char)
146  *
147  * The USE_HARD_TABS switch controls whether it is reliable to use tab/backtabs
148  * for local motions.  On many systems, it's not, due to uncertainties about
149  * tab delays and whether or not tabs will be expanded in raw mode.  If you
150  * have parm_right_cursor, tab motions don't win you a lot anyhow.
151  */
152 
153 #include <curses.priv.h>
154 #include <term.h>
155 #include <ctype.h>
156 
157 MODULE_ID("$From: lib_mvcur.c,v 1.77 2000/12/10 03:04:30 tom Exp $")
158 
159 #define CURRENT_ROW	SP->_cursrow	/* phys cursor row */
160 #define CURRENT_COLUMN	SP->_curscol	/* phys cursor column */
161 #define CURRENT_ATTR	SP->_current_attr	/* current phys attribute */
162 #define REAL_ATTR	SP->_current_attr	/* phys current attribute */
163 #define WANT_CHAR(y, x)	SP->_newscr->_line[y].text[x]	/* desired state */
164 #define BAUDRATE	cur_term->_baudrate	/* bits per second */
165 
166 #if defined(MAIN) || defined(NCURSES_TEST)
167 #include <sys/time.h>
168 
169 static bool profiling = FALSE;
170 static float diff;
171 #endif /* MAIN */
172 
173 #define OPT_SIZE 512
174 
175 static int normalized_cost(const char *const cap, int affcnt);
176 
177 /****************************************************************************
178  *
179  * Initialization/wrapup (including cost pre-computation)
180  *
181  ****************************************************************************/
182 
183 #ifdef TRACE
184 static int
185 trace_cost_of(const char *capname, const char *cap, int affcnt)
186 {
187     int result = _nc_msec_cost(cap, affcnt);
188     TR(TRACE_CHARPUT | TRACE_MOVE,
189        ("CostOf %s %d %s", capname, result, _nc_visbuf(cap)));
190     return result;
191 }
192 #define CostOf(cap,affcnt) trace_cost_of(#cap,cap,affcnt);
193 
194 static int
195 trace_normalized_cost(const char *capname, const char *cap, int affcnt)
196 {
197     int result = normalized_cost(cap, affcnt);
198     TR(TRACE_CHARPUT | TRACE_MOVE,
199        ("NormalizedCost %s %d %s", capname, result, _nc_visbuf(cap)));
200     return result;
201 }
202 #define NormalizedCost(cap,affcnt) trace_normalized_cost(#cap,cap,affcnt);
203 
204 #else
205 
206 #define CostOf(cap,affcnt) _nc_msec_cost(cap,affcnt);
207 #define NormalizedCost(cap,affcnt) normalized_cost(cap,affcnt);
208 
209 #endif
210 
211 NCURSES_EXPORT(int)
212 _nc_msec_cost
213 (const char *const cap, int affcnt)
214 /* compute the cost of a given operation */
215 {
216     if (cap == 0)
217 	return (INFINITY);
218     else {
219 	const char *cp;
220 	float cum_cost = 0.0;
221 
222 	for (cp = cap; *cp; cp++) {
223 	    /* extract padding, either mandatory or required */
224 	    if (cp[0] == '$' && cp[1] == '<' && strchr(cp, '>')) {
225 		float number = 0.0;
226 
227 		for (cp += 2; *cp != '>'; cp++) {
228 		    if (isdigit(CharOf(*cp)))
229 			number = number * 10 + (*cp - '0');
230 		    else if (*cp == '*')
231 			number *= affcnt;
232 		    else if (*cp == '.' && (*++cp != '>') && isdigit(CharOf(*cp)))
233 			number += (*cp - '0') / 10.0;
234 		}
235 
236 #if NCURSES_NO_PADDING
237 		if (!(SP->_no_padding))
238 #endif
239 		    cum_cost += number * 10;
240 	    } else
241 		cum_cost += SP->_char_padding;
242 	}
243 
244 	return ((int) cum_cost);
245     }
246 }
247 
248 static int
249 normalized_cost(const char *const cap, int affcnt)
250 /* compute the effective character-count for an operation (round up) */
251 {
252     int cost = _nc_msec_cost(cap, affcnt);
253     if (cost != INFINITY)
254 	cost = (cost + SP->_char_padding - 1) / SP->_char_padding;
255     return cost;
256 }
257 
258 static void
259 reset_scroll_region(void)
260 /* Set the scroll-region to a known state (the default) */
261 {
262     if (change_scroll_region) {
263 	TPUTS_TRACE("change_scroll_region");
264 	putp(tparm(change_scroll_region, 0, screen_lines - 1));
265     }
266 }
267 
268 NCURSES_EXPORT(void)
269 _nc_mvcur_resume(void)
270 /* what to do at initialization time and after each shellout */
271 {
272     /* initialize screen for cursor access */
273     if (enter_ca_mode) {
274 	TPUTS_TRACE("enter_ca_mode");
275 	putp(enter_ca_mode);
276     }
277 
278     /*
279      * Doing this here rather than in _nc_mvcur_wrap() ensures that
280      * ncurses programs will see a reset scroll region even if a
281      * program that messed with it died ungracefully.
282      *
283      * This also undoes the effects of terminal init strings that assume
284      * they know the screen size.  This is useful when you're running
285      * a vt100 emulation through xterm.
286      */
287     reset_scroll_region();
288     SP->_cursrow = SP->_curscol = -1;
289 
290     /* restore cursor shape */
291     if (SP->_cursor != -1) {
292 	int cursor = SP->_cursor;
293 	SP->_cursor = -1;
294 	curs_set(cursor);
295     }
296 }
297 
298 NCURSES_EXPORT(void)
299 _nc_mvcur_init(void)
300 /* initialize the cost structure */
301 {
302     /*
303      * 9 = 7 bits + 1 parity + 1 stop.
304      */
305     SP->_char_padding = (9 * 1000 * 10) / (BAUDRATE > 0 ? BAUDRATE : 9600);
306     if (SP->_char_padding <= 0)
307 	SP->_char_padding = 1;	/* must be nonzero */
308     TR(TRACE_CHARPUT | TRACE_MOVE, ("char_padding %d msecs", SP->_char_padding));
309 
310     /* non-parameterized local-motion strings */
311     SP->_cr_cost = CostOf(carriage_return, 0);
312     SP->_home_cost = CostOf(cursor_home, 0);
313     SP->_ll_cost = CostOf(cursor_to_ll, 0);
314 #if USE_HARD_TABS
315     SP->_ht_cost = CostOf(tab, 0);
316     SP->_cbt_cost = CostOf(back_tab, 0);
317 #endif /* USE_HARD_TABS */
318     SP->_cub1_cost = CostOf(cursor_left, 0);
319     SP->_cuf1_cost = CostOf(cursor_right, 0);
320     SP->_cud1_cost = CostOf(cursor_down, 0);
321     SP->_cuu1_cost = CostOf(cursor_up, 0);
322 
323     SP->_smir_cost = CostOf(enter_insert_mode, 0);
324     SP->_rmir_cost = CostOf(exit_insert_mode, 0);
325     SP->_ip_cost = 0;
326     if (insert_padding) {
327 	SP->_ip_cost = CostOf(insert_padding, 0);
328     }
329 
330     /*
331      * Assumption: if the terminal has memory_relative addressing, the
332      * initialization strings or smcup will set single-page mode so we
333      * can treat it like absolute screen addressing.  This seems to be true
334      * for all cursor_mem_address terminal types in the terminfo database.
335      */
336     SP->_address_cursor = cursor_address ? cursor_address : cursor_mem_address;
337 
338     /*
339      * Parametrized local-motion strings.  This static cost computation
340      * depends on the following assumptions:
341      *
342      * (1) They never have * padding.  In the entire master terminfo database
343      *     as of March 1995, only the obsolete Zenith Z-100 pc violates this.
344      *     (Proportional padding is found mainly in insert, delete and scroll
345      *     capabilities).
346      *
347      * (2) The average case of cup has two two-digit parameters.  Strictly,
348      *     the average case for a 24 * 80 screen has ((10*10*(1 + 1)) +
349      *     (14*10*(1 + 2)) + (10*70*(2 + 1)) + (14*70*4)) / (24*80) = 3.458
350      *     digits of parameters.  On a 25x80 screen the average is 3.6197.
351      *     On larger screens the value gets much closer to 4.
352      *
353      * (3) The average case of cub/cuf/hpa/ech/rep has 2 digits of parameters
354      *     (strictly, (((10 * 1) + (70 * 2)) / 80) = 1.8750).
355      *
356      * (4) The average case of cud/cuu/vpa has 2 digits of parameters
357      *     (strictly, (((10 * 1) + (14 * 2)) / 24) = 1.5833).
358      *
359      * All these averages depend on the assumption that all parameter values
360      * are equally probable.
361      */
362     SP->_cup_cost = CostOf(tparm(SP->_address_cursor, 23, 23), 1);
363     SP->_cub_cost = CostOf(tparm(parm_left_cursor, 23), 1);
364     SP->_cuf_cost = CostOf(tparm(parm_right_cursor, 23), 1);
365     SP->_cud_cost = CostOf(tparm(parm_down_cursor, 23), 1);
366     SP->_cuu_cost = CostOf(tparm(parm_up_cursor, 23), 1);
367     SP->_hpa_cost = CostOf(tparm(column_address, 23), 1);
368     SP->_vpa_cost = CostOf(tparm(row_address, 23), 1);
369 
370     /* non-parameterized screen-update strings */
371     SP->_ed_cost = NormalizedCost(clr_eos, 1);
372     SP->_el_cost = NormalizedCost(clr_eol, 1);
373     SP->_el1_cost = NormalizedCost(clr_bol, 1);
374     SP->_dch1_cost = NormalizedCost(delete_character, 1);
375     SP->_ich1_cost = NormalizedCost(insert_character, 1);
376 
377     /* parameterized screen-update strings */
378     SP->_dch_cost = NormalizedCost(tparm(parm_dch, 23), 1);
379     SP->_ich_cost = NormalizedCost(tparm(parm_ich, 23), 1);
380     SP->_ech_cost = NormalizedCost(tparm(erase_chars, 23), 1);
381     SP->_rep_cost = NormalizedCost(tparm(repeat_char, ' ', 23), 1);
382 
383     SP->_cup_ch_cost = NormalizedCost(tparm(SP->_address_cursor, 23, 23), 1);
384     SP->_hpa_ch_cost = NormalizedCost(tparm(column_address, 23), 1);
385     SP->_cuf_ch_cost = NormalizedCost(tparm(parm_right_cursor, 23), 1);
386     SP->_inline_cost = min(SP->_cup_ch_cost,
387 			   min(SP->_hpa_ch_cost,
388 			       SP->_cuf_ch_cost));
389 
390     /*
391      * If save_cursor is used within enter_ca_mode, we should not use it for
392      * scrolling optimization, since the corresponding restore_cursor is not
393      * nested on the various terminals (vt100, xterm, etc.) which use this
394      * feature.
395      */
396     if (save_cursor != 0
397 	&& enter_ca_mode != 0
398 	&& strstr(enter_ca_mode, save_cursor) != 0) {
399 	T(("...suppressed sc/rc capability due to conflict with smcup/rmcup"));
400 	save_cursor = 0;
401 	restore_cursor = 0;
402     }
403 
404     /*
405      * A different, possibly better way to arrange this would be to set
406      * SP->_endwin = TRUE at window initialization time and let this be
407      * called by doupdate's return-from-shellout code.
408      */
409     _nc_mvcur_resume();
410 }
411 
412 NCURSES_EXPORT(void)
413 _nc_mvcur_wrap(void)
414 /* wrap up cursor-addressing mode */
415 {
416     /* leave cursor at screen bottom */
417     mvcur(-1, -1, screen_lines - 1, 0);
418 
419     /* set cursor to normal mode */
420     if (SP->_cursor != -1)
421 	curs_set(1);
422 
423     if (exit_ca_mode) {
424 	TPUTS_TRACE("exit_ca_mode");
425 	putp(exit_ca_mode);
426     }
427     /*
428      * Reset terminal's tab counter.  There's a long-time bug that
429      * if you exit a "curses" program such as vi or more, tab
430      * forward, and then backspace, the cursor doesn't go to the
431      * right place.  The problem is that the kernel counts the
432      * escape sequences that reset things as column positions.
433      * Utter a \r to reset this invisibly.
434      */
435     _nc_outch('\r');
436 }
437 
438 /****************************************************************************
439  *
440  * Optimized cursor movement
441  *
442  ****************************************************************************/
443 
444 /*
445  * Perform repeated-append, returning cost
446  */
447 static inline int
448 repeated_append(string_desc * target, int total, int num, int repeat, const char *src)
449 {
450     size_t need = repeat * strlen(src);
451 
452     if (need < target->s_size) {
453 	while (repeat-- > 0) {
454 	    if (_nc_safe_strcat(target, src)) {
455 		total += num;
456 	    } else {
457 		total = INFINITY;
458 		break;
459 	    }
460 	}
461     } else {
462 	total = INFINITY;
463     }
464     return total;
465 }
466 
467 #ifndef NO_OPTIMIZE
468 #define NEXTTAB(fr)	(fr + init_tabs - (fr % init_tabs))
469 
470 /*
471  * Assume back_tab (CBT) does not wrap backwards at the left margin, return
472  * a negative value at that point to simplify the loop.
473  */
474 #define LASTTAB(fr)	((fr > 0) ? ((fr - 1) / init_tabs) * init_tabs : -1)
475 
476 static int
477 relative_move(string_desc * target, int from_y, int from_x, int to_y, int
478 	      to_x, bool ovw)
479 /* move via local motions (cuu/cuu1/cud/cud1/cub1/cub/cuf1/cuf/vpa/hpa) */
480 {
481     string_desc save;
482     int n, vcost = 0, hcost = 0;
483 
484     (void) _nc_str_copy(&save, target);
485 
486     if (to_y != from_y) {
487 	vcost = INFINITY;
488 
489 	if (row_address != 0
490 	    && _nc_safe_strcat(target, tparm(row_address, to_y))) {
491 	    vcost = SP->_vpa_cost;
492 	}
493 
494 	if (to_y > from_y) {
495 	    n = (to_y - from_y);
496 
497 	    if (parm_down_cursor
498 		&& SP->_cud_cost < vcost
499 		&& _nc_safe_strcat(_nc_str_copy(target, &save),
500 				   tparm(parm_down_cursor, n))) {
501 		vcost = SP->_cud_cost;
502 	    }
503 
504 	    if (cursor_down && (n * SP->_cud1_cost < vcost)) {
505 		vcost = repeated_append(_nc_str_copy(target, &save), 0,
506 					SP->_cud1_cost, n, cursor_down);
507 	    }
508 	} else {		/* (to_y < from_y) */
509 	    n = (from_y - to_y);
510 
511 	    if (parm_up_cursor
512 		&& SP->_cup_cost < vcost
513 		&& _nc_safe_strcat(_nc_str_copy(target, &save),
514 				   tparm(parm_up_cursor, n))) {
515 		vcost = SP->_cup_cost;
516 	    }
517 
518 	    if (cursor_up && (n * SP->_cuu1_cost < vcost)) {
519 		vcost = repeated_append(_nc_str_copy(target, &save), 0,
520 					SP->_cuu1_cost, n, cursor_up);
521 	    }
522 	}
523 
524 	if (vcost == INFINITY)
525 	    return (INFINITY);
526     }
527 
528     save = *target;
529 
530     if (to_x != from_x) {
531 	char str[OPT_SIZE];
532 	string_desc check;
533 
534 	hcost = INFINITY;
535 
536 	if (column_address
537 	    && _nc_safe_strcat(_nc_str_copy(target, &save),
538 			       tparm(column_address, to_x))) {
539 	    hcost = SP->_hpa_cost;
540 	}
541 
542 	if (to_x > from_x) {
543 	    n = to_x - from_x;
544 
545 	    if (parm_right_cursor
546 		&& SP->_cuf_cost < hcost
547 		&& _nc_safe_strcat(_nc_str_copy(target, &save),
548 				   tparm(parm_right_cursor, n))) {
549 		hcost = SP->_cuf_cost;
550 	    }
551 
552 	    if (cursor_right) {
553 		int lhcost = 0;
554 
555 		(void) _nc_str_init(&check, str, sizeof(str));
556 
557 #if USE_HARD_TABS
558 		/* use hard tabs, if we have them, to do as much as possible */
559 		if (init_tabs > 0 && tab) {
560 		    int nxt, fr;
561 
562 		    for (fr = from_x; (nxt = NEXTTAB(fr)) <= to_x; fr = nxt) {
563 			lhcost = repeated_append(&check, lhcost,
564 						 SP->_ht_cost, 1, tab);
565 			if (lhcost == INFINITY)
566 			    break;
567 		    }
568 
569 		    n = to_x - fr;
570 		    from_x = fr;
571 		}
572 #endif /* USE_HARD_TABS */
573 
574 #if defined(REAL_ATTR) && defined(WANT_CHAR)
575 		if (n <= 0 || n >= (int) check.s_size)
576 		    ovw = FALSE;
577 #if BSD_TPUTS
578 		/*
579 		 * If we're allowing BSD-style padding in tputs, don't generate
580 		 * a string with a leading digit.  Otherwise, that will be
581 		 * interpreted as a padding value rather than sent to the
582 		 * screen.
583 		 */
584 		if (ovw
585 		    && n > 0
586 		    && n < (int) check.s_size
587 		    && vcost == 0
588 		    && str[0] == '\0'
589 		    && isdigit(TextOf(WANT_CHAR(to_y, from_x))))
590 		    ovw = FALSE;
591 #endif
592 		/*
593 		 * If we have no attribute changes, overwrite is cheaper.
594 		 * Note: must suppress this by passing in ovw = FALSE whenever
595 		 * WANT_CHAR would return invalid data.  In particular, this
596 		 * is true between the time a hardware scroll has been done
597 		 * and the time the structure WANT_CHAR would access has been
598 		 * updated.
599 		 */
600 		if (ovw) {
601 		    int i;
602 
603 		    for (i = 0; i < n; i++)
604 			if ((WANT_CHAR(to_y, from_x + i) & A_ATTRIBUTES) != CURRENT_ATTR) {
605 			    ovw = FALSE;
606 			    break;
607 			}
608 		}
609 		if (ovw) {
610 		    int i;
611 
612 		    for (i = 0; i < n; i++)
613 			*check.s_tail++ = WANT_CHAR(to_y, from_x + i);
614 		    *check.s_tail = '\0';
615 		    check.s_size -= n;
616 		    lhcost += n * SP->_char_padding;
617 		} else
618 #endif /* defined(REAL_ATTR) && defined(WANT_CHAR) */
619 		{
620 		    lhcost = repeated_append(&check, lhcost, SP->_cuf1_cost,
621 					     n, cursor_right);
622 		}
623 
624 		if (lhcost < hcost
625 		    && _nc_safe_strcat(_nc_str_copy(target, &save), str)) {
626 		    hcost = lhcost;
627 		}
628 	    }
629 	} else {		/* (to_x < from_x) */
630 	    n = from_x - to_x;
631 
632 	    if (parm_left_cursor
633 		&& SP->_cub_cost < hcost
634 		&& _nc_safe_strcat(_nc_str_copy(target, &save),
635 				   tparm(parm_left_cursor, n))) {
636 		hcost = SP->_cub_cost;
637 	    }
638 
639 	    if (cursor_left) {
640 		int lhcost = 0;
641 
642 		(void) _nc_str_init(&check, str, sizeof(str));
643 
644 #if USE_HARD_TABS
645 		if (init_tabs > 0 && back_tab) {
646 		    int nxt, fr;
647 
648 		    for (fr = from_x; (nxt = LASTTAB(fr)) >= to_x; fr = nxt) {
649 			lhcost = repeated_append(&check, lhcost,
650 						 SP->_cbt_cost, 1, back_tab);
651 			if (lhcost == INFINITY)
652 			    break;
653 		    }
654 
655 		    n = fr - to_x;
656 		}
657 #endif /* USE_HARD_TABS */
658 
659 		lhcost = repeated_append(&check, lhcost, SP->_cub1_cost, n, cursor_left);
660 
661 		if (lhcost < hcost
662 		    && _nc_safe_strcat(_nc_str_copy(target, &save), str)) {
663 		    hcost = lhcost;
664 		}
665 	    }
666 	}
667 
668 	if (hcost == INFINITY)
669 	    return (INFINITY);
670     }
671 
672     return (vcost + hcost);
673 }
674 #endif /* !NO_OPTIMIZE */
675 
676 /*
677  * With the machinery set up above, it's conceivable that
678  * onscreen_mvcur could be modified into a recursive function that does
679  * an alpha-beta search of motion space, as though it were a chess
680  * move tree, with the weight function being boolean and the search
681  * depth equated to length of string.  However, this would jack up the
682  * computation cost a lot, especially on terminals without a cup
683  * capability constraining the search tree depth.  So we settle for
684  * the simpler method below.
685  */
686 
687 static inline int
688 onscreen_mvcur(int yold, int xold, int ynew, int xnew, bool ovw)
689 /* onscreen move from (yold, xold) to (ynew, xnew) */
690 {
691     string_desc result;
692     char buffer[OPT_SIZE];
693     int tactic = 0, newcost, usecost = INFINITY;
694     int t5_cr_cost;
695 
696 #if defined(MAIN) || defined(NCURSES_TEST)
697     struct timeval before, after;
698 
699     gettimeofday(&before, NULL);
700 #endif /* MAIN */
701 
702 #define NullResult _nc_str_null(&result, sizeof(buffer))
703 #define InitResult _nc_str_init(&result, buffer, sizeof(buffer))
704 
705     /* tactic #0: use direct cursor addressing */
706     if (_nc_safe_strcpy(InitResult, tparm(SP->_address_cursor, ynew, xnew))) {
707 	tactic = 0;
708 	usecost = SP->_cup_cost;
709 
710 #if defined(TRACE) || defined(NCURSES_TEST)
711 	if (!(_nc_optimize_enable & OPTIMIZE_MVCUR))
712 	    goto nonlocal;
713 #endif /* TRACE */
714 
715 	/*
716 	 * We may be able to tell in advance that the full optimization
717 	 * will probably not be worth its overhead.  Also, don't try to
718 	 * use local movement if the current attribute is anything but
719 	 * A_NORMAL...there are just too many ways this can screw up
720 	 * (like, say, local-movement \n getting mapped to some obscure
721 	 * character because A_ALTCHARSET is on).
722 	 */
723 	if (yold == -1 || xold == -1 || NOT_LOCAL(yold, xold, ynew, xnew)) {
724 #if defined(MAIN) || defined(NCURSES_TEST)
725 	    if (!profiling) {
726 		(void) fputs("nonlocal\n", stderr);
727 		goto nonlocal;	/* always run the optimizer if profiling */
728 	    }
729 #else
730 	    goto nonlocal;
731 #endif /* MAIN */
732 	}
733     }
734 #ifndef NO_OPTIMIZE
735     /* tactic #1: use local movement */
736     if (yold != -1 && xold != -1
737 	&& ((newcost = relative_move(NullResult, yold, xold, ynew, xnew,
738 				     ovw)) != INFINITY)
739 	&& newcost < usecost) {
740 	tactic = 1;
741 	usecost = newcost;
742     }
743 
744     /* tactic #2: use carriage-return + local movement */
745     if (yold != -1 && carriage_return
746 	&& ((newcost = relative_move(NullResult, yold, 0, ynew, xnew, ovw))
747 	    != INFINITY)
748 	&& SP->_cr_cost + newcost < usecost) {
749 	tactic = 2;
750 	usecost = SP->_cr_cost + newcost;
751     }
752 
753     /* tactic #3: use home-cursor + local movement */
754     if (cursor_home
755 	&& ((newcost = relative_move(NullResult, 0, 0, ynew, xnew, ovw)) != INFINITY)
756 	&& SP->_home_cost + newcost < usecost) {
757 	tactic = 3;
758 	usecost = SP->_home_cost + newcost;
759     }
760 
761     /* tactic #4: use home-down + local movement */
762     if (cursor_to_ll
763 	&& ((newcost = relative_move(NullResult, screen_lines - 1, 0, ynew,
764 				     xnew, ovw)) != INFINITY)
765 	&& SP->_ll_cost + newcost < usecost) {
766 	tactic = 4;
767 	usecost = SP->_ll_cost + newcost;
768     }
769 
770     /*
771      * tactic #5: use left margin for wrap to right-hand side,
772      * unless strange wrap behavior indicated by xenl might hose us.
773      */
774     t5_cr_cost = (xold > 0 ? SP->_cr_cost : 0);
775     if (auto_left_margin && !eat_newline_glitch
776 	&& yold > 0 && cursor_left
777 	&& ((newcost = relative_move(NullResult, yold - 1, screen_columns -
778 				     1, ynew, xnew, ovw)) != INFINITY)
779 	&& t5_cr_cost + SP->_cub1_cost + newcost < usecost) {
780 	tactic = 5;
781 	usecost = t5_cr_cost + SP->_cub1_cost + newcost;
782     }
783 
784     /*
785      * These cases are ordered by estimated relative frequency.
786      */
787     if (tactic)
788 	InitResult;
789     switch (tactic) {
790     case 1:
791 	(void) relative_move(&result, yold, xold, ynew, xnew, ovw);
792 	break;
793     case 2:
794 	(void) _nc_safe_strcpy(&result, carriage_return);
795 	(void) relative_move(&result, yold, 0, ynew, xnew, ovw);
796 	break;
797     case 3:
798 	(void) _nc_safe_strcpy(&result, cursor_home);
799 	(void) relative_move(&result, 0, 0, ynew, xnew, ovw);
800 	break;
801     case 4:
802 	(void) _nc_safe_strcpy(&result, cursor_to_ll);
803 	(void) relative_move(&result, screen_lines - 1, 0, ynew, xnew, ovw);
804 	break;
805     case 5:
806 	if (xold > 0)
807 	    (void) _nc_safe_strcat(&result, carriage_return);
808 	(void) _nc_safe_strcat(&result, cursor_left);
809 	(void) relative_move(&result, yold - 1, screen_columns - 1, ynew,
810 			     xnew, ovw);
811 	break;
812     }
813 #endif /* !NO_OPTIMIZE */
814 
815 #if defined(MAIN) || defined(NCURSES_TEST)
816     gettimeofday(&after, NULL);
817     diff = after.tv_usec - before.tv_usec
818 	+ (after.tv_sec - before.tv_sec) * 1000000;
819     if (!profiling)
820 	(void) fprintf(stderr,
821 		       "onscreen: %d msec, %f 28.8Kbps char-equivalents\n",
822 		       (int) diff, diff / 288);
823 #endif /* MAIN */
824 
825   nonlocal:
826     if (usecost != INFINITY) {
827 	TPUTS_TRACE("mvcur");
828 	tputs(buffer, 1, _nc_outch);
829 	return (OK);
830     } else
831 	return (ERR);
832 }
833 
834 NCURSES_EXPORT(int)
835 mvcur
836 (int yold, int xold, int ynew, int xnew)
837 /* optimized cursor move from (yold, xold) to (ynew, xnew) */
838 {
839     TR(TRACE_MOVE, ("mvcur(%d,%d,%d,%d) called", yold, xold, ynew, xnew));
840 
841     if (yold == ynew && xold == xnew)
842 	return (OK);
843 
844     /*
845      * Most work here is rounding for terminal boundaries getting the
846      * column position implied by wraparound or the lack thereof and
847      * rolling up the screen to get ynew on the screen.
848      */
849 
850     if (xnew >= screen_columns) {
851 	ynew += xnew / screen_columns;
852 	xnew %= screen_columns;
853     }
854     if (xold >= screen_columns) {
855 	int l;
856 
857 	l = (xold + 1) / screen_columns;
858 	yold += l;
859 	if (yold >= screen_lines)
860 	    l -= (yold - screen_lines - 1);
861 
862 	while (l > 0) {
863 	    if (newline) {
864 		TPUTS_TRACE("newline");
865 		tputs(newline, 0, _nc_outch);
866 	    } else
867 		putchar('\n');
868 	    l--;
869 	    if (xold > 0) {
870 		if (carriage_return) {
871 		    TPUTS_TRACE("carriage_return");
872 		    tputs(carriage_return, 0, _nc_outch);
873 		} else
874 		    putchar('\r');
875 		xold = 0;
876 	    }
877 	}
878     }
879 
880     if (yold > screen_lines - 1)
881 	yold = screen_lines - 1;
882     if (ynew > screen_lines - 1)
883 	ynew = screen_lines - 1;
884 
885     /* destination location is on screen now */
886     return (onscreen_mvcur(yold, xold, ynew, xnew, TRUE));
887 }
888 
889 #if defined(TRACE) || defined(NCURSES_TEST)
890 NCURSES_EXPORT_VAR(int) _nc_optimize_enable = OPTIMIZE_ALL;
891 #endif
892 
893 #if defined(MAIN) || defined(NCURSES_TEST)
894 /****************************************************************************
895  *
896  * Movement optimizer test code
897  *
898  ****************************************************************************/
899 
900 #include <tic.h>
901 #include <dump_entry.h>
902 
903 NCURSES_EXPORT_VAR(const char *)
904 _nc_progname = "mvcur";
905 
906      static unsigned long xmits;
907 
908 /* these override lib_tputs.c */
909 NCURSES_EXPORT(int)
910 tputs
911 (const char *string, int affcnt GCC_UNUSED, int (*outc) (int) GCC_UNUSED)
912 /* stub tputs() that dumps sequences in a visible form */
913 {
914     if (profiling)
915 	xmits += strlen(string);
916     else
917 	(void) fputs(_nc_visbuf(string), stdout);
918     return (OK);
919 }
920 
921 NCURSES_EXPORT(int)
922 putp(const char *string)
923 {
924     return (tputs(string, 1, _nc_outch));
925 }
926 
927 NCURSES_EXPORT(int)
928 _nc_outch(int ch)
929 {
930     putc(ch, stdout);
931     return OK;
932 }
933 
934 NCURSES_EXPORT_VAR(char) PC = 0;	/* used by termcap library */
935 NCURSES_EXPORT_VAR(NCURSES_OSPEED) ospeed = 0;	/* used by termcap library */
936 NCURSES_EXPORT_VAR(int)
937 _nc_nulls_sent = 0;		/* used by 'tack' program */
938 
939 NCURSES_EXPORT(int)
940 delay_output(int ms GCC_UNUSED)
941 {
942     return OK;
943 }
944 
945 static char tname[MAX_ALIAS];
946 
947 static void
948 load_term(void)
949 {
950     (void) setupterm(tname, STDOUT_FILENO, NULL);
951 }
952 
953 static int
954 roll(int n)
955 {
956     int i, j;
957 
958     i = (RAND_MAX / n) * n;
959     while ((j = rand()) >= i)
960 	continue;
961     return (j % n);
962 }
963 
964 int
965 main(int argc GCC_UNUSED, char *argv[]GCC_UNUSED)
966 {
967     (void) strlcpy(tname, termname(), sizeof(tname));
968     load_term();
969     _nc_setupscreen(lines, columns, stdout);
970     baudrate();
971 
972     _nc_mvcur_init();
973     NC_BUFFERED(FALSE);
974 
975     (void) puts("The mvcur tester.  Type ? for help");
976 
977     fputs("smcup:", stdout);
978     putchar('\n');
979 
980     for (;;) {
981 	int fy, fx, ty, tx, n, i;
982 	char buf[BUFSIZ], capname[BUFSIZ];
983 
984 	(void) fputs("> ", stdout);
985 	if (fgets(buf, sizeof(buf), stdin) == NULL) {
986 	    if (ferror(stdin))
987 	    	fputs("ferror on stdin", stderr);
988 	    break;
989 	}
990 
991 	if (buf[0] == '?') {
992 	    (void) puts("?                -- display this help message");
993 	    (void)
994 		puts("fy fx ty tx      -- (4 numbers) display (fy,fx)->(ty,tx) move");
995 	    (void) puts("s[croll] n t b m -- display scrolling sequence");
996 	    (void)
997 		printf("r[eload]         -- reload terminal info for %s\n",
998 		       termname());
999 	    (void)
1000 		puts("l[oad] <term>    -- load terminal info for type <term>");
1001 	    (void) puts("d[elete] <cap>   -- delete named capability");
1002 	    (void) puts("i[nspect]        -- display terminal capabilities");
1003 	    (void)
1004 		puts("c[ost]           -- dump cursor-optimization cost table");
1005 	    (void) puts("o[optimize]      -- toggle movement optimization");
1006 	    (void)
1007 		puts("t[orture] <num>  -- torture-test with <num> random moves");
1008 	    (void) puts("q[uit]           -- quit the program");
1009 	} else if (sscanf(buf, "%d %d %d %d", &fy, &fx, &ty, &tx) == 4) {
1010 	    struct timeval before, after;
1011 
1012 	    putchar('"');
1013 
1014 	    gettimeofday(&before, NULL);
1015 	    mvcur(fy, fx, ty, tx);
1016 	    gettimeofday(&after, NULL);
1017 
1018 	    printf("\" (%ld msec)\n",
1019 		   (long) (after.tv_usec - before.tv_usec
1020 			   + (after.tv_sec - before.tv_sec)
1021 			   * 1000000));
1022 	} else if (sscanf(buf, "s %d %d %d %d", &fy, &fx, &ty, &tx) == 4) {
1023 	    struct timeval before, after;
1024 
1025 	    putchar('"');
1026 
1027 	    gettimeofday(&before, NULL);
1028 	    _nc_scrolln(fy, fx, ty, tx);
1029 	    gettimeofday(&after, NULL);
1030 
1031 	    printf("\" (%ld msec)\n",
1032 		   (long) (after.tv_usec - before.tv_usec + (after.tv_sec -
1033 							     before.tv_sec)
1034 			   * 1000000));
1035 	} else if (buf[0] == 'r') {
1036 	    (void) strlcpy(tname, termname(), sizeof(tname));
1037 	    load_term();
1038 	} else if (sscanf(buf, "l %s", tname) == 1) {
1039 	    load_term();
1040 	} else if (sscanf(buf, "d %s", capname) == 1) {
1041 	    struct name_table_entry const *np = _nc_find_entry(capname,
1042 							       _nc_info_hash_table);
1043 
1044 	    if (np == NULL)
1045 		(void) printf("No such capability as \"%s\"\n", capname);
1046 	    else {
1047 		switch (np->nte_type) {
1048 		case BOOLEAN:
1049 		    cur_term->type.Booleans[np->nte_index] = FALSE;
1050 		    (void)
1051 			printf("Boolean capability `%s' (%d) turned off.\n",
1052 			       np->nte_name, np->nte_index);
1053 		    break;
1054 
1055 		case NUMBER:
1056 		    cur_term->type.Numbers[np->nte_index] = ABSENT_NUMERIC;
1057 		    (void) printf("Number capability `%s' (%d) set to -1.\n",
1058 				  np->nte_name, np->nte_index);
1059 		    break;
1060 
1061 		case STRING:
1062 		    cur_term->type.Strings[np->nte_index] = ABSENT_STRING;
1063 		    (void) printf("String capability `%s' (%d) deleted.\n",
1064 				  np->nte_name, np->nte_index);
1065 		    break;
1066 		}
1067 	    }
1068 	} else if (buf[0] == 'i') {
1069 	    dump_init((char *) NULL, F_TERMINFO, S_TERMINFO, 70, 0, FALSE);
1070 	    dump_entry(&cur_term->type, FALSE, TRUE, 0);
1071 	    putchar('\n');
1072 	} else if (buf[0] == 'o') {
1073 	    if (_nc_optimize_enable & OPTIMIZE_MVCUR) {
1074 		_nc_optimize_enable &= ~OPTIMIZE_MVCUR;
1075 		(void) puts("Optimization is now off.");
1076 	    } else {
1077 		_nc_optimize_enable |= OPTIMIZE_MVCUR;
1078 		(void) puts("Optimization is now on.");
1079 	    }
1080 	}
1081 	/*
1082 	 * You can use the `t' test to profile and tune the movement
1083 	 * optimizer.  Use iteration values in three digits or more.
1084 	 * At above 5000 iterations the profile timing averages are stable
1085 	 * to within a millisecond or three.
1086 	 *
1087 	 * The `overhead' field of the report will help you pick a
1088 	 * COMPUTE_OVERHEAD figure appropriate for your processor and
1089 	 * expected line speed.  The `total estimated time' is
1090 	 * computation time plus a character-transmission time
1091 	 * estimate computed from the number of transmits and the baud
1092 	 * rate.
1093 	 *
1094 	 * Use this together with the `o' command to get a read on the
1095 	 * optimizer's effectiveness.  Compare the total estimated times
1096 	 * for `t' runs of the same length in both optimized and un-optimized
1097 	 * modes.  As long as the optimized times are less, the optimizer
1098 	 * is winning.
1099 	 */
1100 	else if (sscanf(buf, "t %d", &n) == 1) {
1101 	    float cumtime = 0.0, perchar;
1102 	    int speeds[] =
1103 	    {2400, 9600, 14400, 19200, 28800, 38400, 0};
1104 
1105 	    srand((unsigned) (getpid() + time((time_t *) 0)));
1106 	    profiling = TRUE;
1107 	    xmits = 0;
1108 	    for (i = 0; i < n; i++) {
1109 		/*
1110 		 * This does a move test between two random locations,
1111 		 * Random moves probably short-change the optimizer,
1112 		 * which will work better on the short moves probably
1113 		 * typical of doupdate()'s usage pattern.  Still,
1114 		 * until we have better data...
1115 		 */
1116 #ifdef FIND_COREDUMP
1117 		int from_y = roll(lines);
1118 		int to_y = roll(lines);
1119 		int from_x = roll(columns);
1120 		int to_x = roll(columns);
1121 
1122 		printf("(%d,%d) -> (%d,%d)\n", from_y, from_x, to_y, to_x);
1123 		mvcur(from_y, from_x, to_y, to_x);
1124 #else
1125 		mvcur(roll(lines), roll(columns), roll(lines), roll(columns));
1126 #endif /* FIND_COREDUMP */
1127 		if (diff)
1128 		    cumtime += diff;
1129 	    }
1130 	    profiling = FALSE;
1131 
1132 	    /*
1133 	     * Average milliseconds per character optimization time.
1134 	     * This is the key figure to watch when tuning the optimizer.
1135 	     */
1136 	    perchar = cumtime / n;
1137 
1138 	    (void) printf("%d moves (%ld chars) in %d msec, %f msec each:\n",
1139 			  n, xmits, (int) cumtime, perchar);
1140 
1141 	    for (i = 0; speeds[i]; i++) {
1142 		/*
1143 		 * Total estimated time for the moves, computation and
1144 		 * transmission both. Transmission time is an estimate
1145 		 * assuming 9 bits/char, 8 bits + 1 stop bit.
1146 		 */
1147 		float totalest = cumtime + xmits * 9 * 1e6 / speeds[i];
1148 
1149 		/*
1150 		 * Per-character optimization overhead in character transmits
1151 		 * at the current speed.  Round this to the nearest integer
1152 		 * to figure COMPUTE_OVERHEAD for the speed.
1153 		 */
1154 		float overhead = speeds[i] * perchar / 1e6;
1155 
1156 		(void)
1157 		    printf("%6d bps: %3.2f char-xmits overhead; total estimated time %15.2f\n",
1158 			   speeds[i], overhead, totalest);
1159 	    }
1160 	} else if (buf[0] == 'c') {
1161 	    (void) printf("char padding: %d\n", SP->_char_padding);
1162 	    (void) printf("cr cost: %d\n", SP->_cr_cost);
1163 	    (void) printf("cup cost: %d\n", SP->_cup_cost);
1164 	    (void) printf("home cost: %d\n", SP->_home_cost);
1165 	    (void) printf("ll cost: %d\n", SP->_ll_cost);
1166 #if USE_HARD_TABS
1167 	    (void) printf("ht cost: %d\n", SP->_ht_cost);
1168 	    (void) printf("cbt cost: %d\n", SP->_cbt_cost);
1169 #endif /* USE_HARD_TABS */
1170 	    (void) printf("cub1 cost: %d\n", SP->_cub1_cost);
1171 	    (void) printf("cuf1 cost: %d\n", SP->_cuf1_cost);
1172 	    (void) printf("cud1 cost: %d\n", SP->_cud1_cost);
1173 	    (void) printf("cuu1 cost: %d\n", SP->_cuu1_cost);
1174 	    (void) printf("cub cost: %d\n", SP->_cub_cost);
1175 	    (void) printf("cuf cost: %d\n", SP->_cuf_cost);
1176 	    (void) printf("cud cost: %d\n", SP->_cud_cost);
1177 	    (void) printf("cuu cost: %d\n", SP->_cuu_cost);
1178 	    (void) printf("hpa cost: %d\n", SP->_hpa_cost);
1179 	    (void) printf("vpa cost: %d\n", SP->_vpa_cost);
1180 	} else if (buf[0] == 'x' || buf[0] == 'q')
1181 	    break;
1182 	else
1183 	    (void) puts("Invalid command.");
1184     }
1185 
1186     (void) fputs("rmcup:", stdout);
1187     _nc_mvcur_wrap();
1188     putchar('\n');
1189 
1190     return (0);
1191 }
1192 
1193 #endif /* MAIN */
1194 
1195 /* lib_mvcur.c ends here */
1196