xref: /openbsd-src/lib/libcurses/tty/lib_mvcur.c (revision 1fe33145a0a9b1310a0413297a8deb871918b27f)
1 /*	$OpenBSD: lib_mvcur.c,v 1.7 2000/06/19 03:53:53 millert 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 1.64 2000/05/14 01:25:28 tom Exp $")
158 
159 #define STRLEN(s)       (s != 0) ? strlen(s) : 0
160 
161 #define CURRENT_ROW	SP->_cursrow	/* phys cursor row */
162 #define CURRENT_COLUMN	SP->_curscol	/* phys cursor column */
163 #define CURRENT_ATTR	SP->_current_attr	/* current phys attribute */
164 #define REAL_ATTR	SP->_current_attr	/* phys current attribute */
165 #define WANT_CHAR(y, x)	SP->_newscr->_line[y].text[x]	/* desired state */
166 #define BAUDRATE	cur_term->_baudrate	/* bits per second */
167 
168 #if defined(MAIN) || defined(NCURSES_TEST)
169 #include <sys/time.h>
170 
171 static bool profiling = FALSE;
172 static float diff;
173 #endif /* MAIN */
174 
175 #define OPT_SIZE 512
176 
177 static int normalized_cost(const char *const cap, int affcnt);
178 
179 #if !HAVE_STRSTR
180 char *
181 _nc_strstr(const char *haystack, const char *needle)
182 {
183     size_t len1 = strlen(haystack);
184     size_t len2 = strlen(needle);
185     char *result = 0;
186 
187     while ((len1 != 0) && (len1-- >= len2)) {
188 	if (!strncmp(haystack, needle, len2)) {
189 	    result = haystack;
190 	    break;
191 	}
192 	haystack++;
193     }
194     return result;
195 }
196 #endif
197 
198 /****************************************************************************
199  *
200  * Initialization/wrapup (including cost pre-computation)
201  *
202  ****************************************************************************/
203 
204 #ifdef TRACE
205 static int
206 trace_cost_of(const char *capname, const char *cap, int affcnt)
207 {
208     int result = _nc_msec_cost(cap, affcnt);
209     TR(TRACE_CHARPUT | TRACE_MOVE, ("CostOf %s %d", capname, result));
210     return result;
211 }
212 #define CostOf(cap,affcnt) trace_cost_of(#cap,cap,affcnt);
213 
214 static int
215 trace_normalized_cost(const char *capname, const char *cap, int affcnt)
216 {
217     int result = normalized_cost(cap, affcnt);
218     TR(TRACE_CHARPUT | TRACE_MOVE, ("NormalizedCost %s %d", capname, result));
219     return result;
220 }
221 #define NormalizedCost(cap,affcnt) trace_normalized_cost(#cap,cap,affcnt);
222 
223 #else
224 
225 #define CostOf(cap,affcnt) _nc_msec_cost(cap,affcnt);
226 #define NormalizedCost(cap,affcnt) normalized_cost(cap,affcnt);
227 
228 #endif
229 
230 int
231 _nc_msec_cost(const char *const cap, int affcnt)
232 /* compute the cost of a given operation */
233 {
234     if (cap == 0)
235 	return (INFINITY);
236     else {
237 	const char *cp;
238 	float cum_cost = 0;
239 
240 	for (cp = cap; *cp; cp++) {
241 	    /* extract padding, either mandatory or required */
242 	    if (cp[0] == '$' && cp[1] == '<' && strchr(cp, '>')) {
243 		float number = 0;
244 
245 		for (cp += 2; *cp != '>'; cp++) {
246 		    if (isdigit(*cp))
247 			number = number * 10 + (*cp - '0');
248 		    else if (*cp == '*')
249 			number *= affcnt;
250 		    else if (*cp == '.' && (*++cp != '>') && isdigit(*cp))
251 			number += (*cp - '0') / 10.0;
252 		}
253 
254 		cum_cost += number * 10;
255 	    } else
256 		cum_cost += SP->_char_padding;
257 	}
258 
259 	return ((int) cum_cost);
260     }
261 }
262 
263 static int
264 normalized_cost(const char *const cap, int affcnt)
265 /* compute the effective character-count for an operation (round up) */
266 {
267     int cost = _nc_msec_cost(cap, affcnt);
268     if (cost != INFINITY)
269 	cost = (cost + SP->_char_padding - 1) / SP->_char_padding;
270     return cost;
271 }
272 
273 static void
274 reset_scroll_region(void)
275 /* Set the scroll-region to a known state (the default) */
276 {
277     if (change_scroll_region) {
278 	TPUTS_TRACE("change_scroll_region");
279 	putp(tparm(change_scroll_region, 0, screen_lines - 1));
280     }
281 }
282 
283 void
284 _nc_mvcur_resume(void)
285 /* what to do at initialization time and after each shellout */
286 {
287     /* initialize screen for cursor access */
288     if (enter_ca_mode) {
289 	TPUTS_TRACE("enter_ca_mode");
290 	putp(enter_ca_mode);
291     }
292 
293     /*
294      * Doing this here rather than in _nc_mvcur_wrap() ensures that
295      * ncurses programs will see a reset scroll region even if a
296      * program that messed with it died ungracefully.
297      *
298      * This also undoes the effects of terminal init strings that assume
299      * they know the screen size.  This is useful when you're running
300      * a vt100 emulation through xterm.
301      */
302     reset_scroll_region();
303     SP->_cursrow = SP->_curscol = -1;
304 
305     /* restore cursor shape */
306     if (SP->_cursor != -1) {
307 	int cursor = SP->_cursor;
308 	SP->_cursor = -1;
309 	curs_set(cursor);
310     }
311 }
312 
313 void
314 _nc_mvcur_init(void)
315 /* initialize the cost structure */
316 {
317     /*
318      * 9 = 7 bits + 1 parity + 1 stop.
319      */
320     SP->_char_padding = (9 * 1000 * 10) / (BAUDRATE > 0 ? BAUDRATE : 9600);
321     if (SP->_char_padding <= 0)
322 	SP->_char_padding = 1;	/* must be nonzero */
323     TR(TRACE_CHARPUT | TRACE_MOVE, ("char_padding %d msecs", SP->_char_padding));
324 
325     /* non-parameterized local-motion strings */
326     SP->_cr_cost = CostOf(carriage_return, 0);
327     SP->_home_cost = CostOf(cursor_home, 0);
328     SP->_ll_cost = CostOf(cursor_to_ll, 0);
329 #if USE_HARD_TABS
330     SP->_ht_cost = CostOf(tab, 0);
331     SP->_cbt_cost = CostOf(back_tab, 0);
332 #endif /* USE_HARD_TABS */
333     SP->_cub1_cost = CostOf(cursor_left, 0);
334     SP->_cuf1_cost = CostOf(cursor_right, 0);
335     SP->_cud1_cost = CostOf(cursor_down, 0);
336     SP->_cuu1_cost = CostOf(cursor_up, 0);
337 
338     SP->_smir_cost = CostOf(enter_insert_mode, 0);
339     SP->_rmir_cost = CostOf(exit_insert_mode, 0);
340     SP->_ip_cost = 0;
341     if (insert_padding) {
342 	SP->_ip_cost = CostOf(insert_padding, 0);
343     }
344 
345     /*
346      * Assumption: if the terminal has memory_relative addressing, the
347      * initialization strings or smcup will set single-page mode so we
348      * can treat it like absolute screen addressing.  This seems to be true
349      * for all cursor_mem_address terminal types in the terminfo database.
350      */
351     SP->_address_cursor = cursor_address ? cursor_address : cursor_mem_address;
352 
353     /*
354      * Parametrized local-motion strings.  This static cost computation
355      * depends on the following assumptions:
356      *
357      * (1) They never have * padding.  In the entire master terminfo database
358      *     as of March 1995, only the obsolete Zenith Z-100 pc violates this.
359      *     (Proportional padding is found mainly in insert, delete and scroll
360      *     capabilities).
361      *
362      * (2) The average case of cup has two two-digit parameters.  Strictly,
363      *     the average case for a 24 * 80 screen has ((10*10*(1 + 1)) +
364      *     (14*10*(1 + 2)) + (10*70*(2 + 1)) + (14*70*4)) / (24*80) = 3.458
365      *     digits of parameters.  On a 25x80 screen the average is 3.6197.
366      *     On larger screens the value gets much closer to 4.
367      *
368      * (3) The average case of cub/cuf/hpa/ech/rep has 2 digits of parameters
369      *     (strictly, (((10 * 1) + (70 * 2)) / 80) = 1.8750).
370      *
371      * (4) The average case of cud/cuu/vpa has 2 digits of parameters
372      *     (strictly, (((10 * 1) + (14 * 2)) / 24) = 1.5833).
373      *
374      * All these averages depend on the assumption that all parameter values
375      * are equally probable.
376      */
377     SP->_cup_cost = CostOf(tparm(SP->_address_cursor, 23, 23), 1);
378     SP->_cub_cost = CostOf(tparm(parm_left_cursor, 23), 1);
379     SP->_cuf_cost = CostOf(tparm(parm_right_cursor, 23), 1);
380     SP->_cud_cost = CostOf(tparm(parm_down_cursor, 23), 1);
381     SP->_cuu_cost = CostOf(tparm(parm_up_cursor, 23), 1);
382     SP->_hpa_cost = CostOf(tparm(column_address, 23), 1);
383     SP->_vpa_cost = CostOf(tparm(row_address, 23), 1);
384 
385     /* non-parameterized screen-update strings */
386     SP->_ed_cost = NormalizedCost(clr_eos, 1);
387     SP->_el_cost = NormalizedCost(clr_eol, 1);
388     SP->_el1_cost = NormalizedCost(clr_bol, 1);
389     SP->_dch1_cost = NormalizedCost(delete_character, 1);
390     SP->_ich1_cost = NormalizedCost(insert_character, 1);
391 
392     /* parameterized screen-update strings */
393     SP->_dch_cost = NormalizedCost(tparm(parm_dch, 23), 1);
394     SP->_ich_cost = NormalizedCost(tparm(parm_ich, 23), 1);
395     SP->_ech_cost = NormalizedCost(tparm(erase_chars, 23), 1);
396     SP->_rep_cost = NormalizedCost(tparm(repeat_char, ' ', 23), 1);
397 
398     SP->_cup_ch_cost = NormalizedCost(tparm(SP->_address_cursor, 23, 23), 1);
399     SP->_hpa_ch_cost = NormalizedCost(tparm(column_address, 23), 1);
400 
401     /* pre-compute some capability lengths */
402     SP->_carriage_return_length = STRLEN(carriage_return);
403     SP->_cursor_home_length = STRLEN(cursor_home);
404     SP->_cursor_to_ll_length = STRLEN(cursor_to_ll);
405 
406     /*
407      * If save_cursor is used within enter_ca_mode, we should not use it for
408      * scrolling optimization, since the corresponding restore_cursor is not
409      * nested on the various terminals (vt100, xterm, etc.) which use this
410      * feature.
411      */
412     if (save_cursor != 0
413 	&& enter_ca_mode != 0
414 	&& strstr(enter_ca_mode, save_cursor) != 0) {
415 	T(("...suppressed sc/rc capability due to conflict with smcup/rmcup"));
416 	save_cursor = 0;
417 	restore_cursor = 0;
418     }
419 
420     /*
421      * A different, possibly better way to arrange this would be to set
422      * SP->_endwin = TRUE at window initialization time and let this be
423      * called by doupdate's return-from-shellout code.
424      */
425     _nc_mvcur_resume();
426 }
427 
428 void
429 _nc_mvcur_wrap(void)
430 /* wrap up cursor-addressing mode */
431 {
432     /* leave cursor at screen bottom */
433     mvcur(-1, -1, screen_lines - 1, 0);
434 
435     /* set cursor to normal mode */
436     if (SP->_cursor != -1)
437 	curs_set(1);
438 
439     if (exit_ca_mode) {
440 	TPUTS_TRACE("exit_ca_mode");
441 	putp(exit_ca_mode);
442     }
443     /*
444      * Reset terminal's tab counter.  There's a long-time bug that
445      * if you exit a "curses" program such as vi or more, tab
446      * forward, and then backspace, the cursor doesn't go to the
447      * right place.  The problem is that the kernel counts the
448      * escape sequences that reset things as column positions.
449      * Utter a \r to reset this invisibly.
450      */
451     _nc_outch('\r');
452 }
453 
454 /****************************************************************************
455  *
456  * Optimized cursor movement
457  *
458  ****************************************************************************/
459 
460 /*
461  * Perform repeated-append, returning cost
462  */
463 static inline int
464 repeated_append(int total, int num, int repeat, char *dst, const char *src)
465 {
466     register size_t src_len = strlen(src);
467     register size_t dst_len = STRLEN(dst);
468 
469     if ((dst_len + repeat * src_len) < OPT_SIZE - 1) {
470 	total += (num * repeat);
471 	if (dst) {
472 	    dst += dst_len;
473 	    while (repeat-- > 0) {
474 		(void) strcpy(dst, src);
475 		dst += src_len;
476 	    }
477 	}
478     } else {
479 	total = INFINITY;
480     }
481     return total;
482 }
483 
484 #ifndef NO_OPTIMIZE
485 #define NEXTTAB(fr)	(fr + init_tabs - (fr % init_tabs))
486 
487 /*
488  * Assume back_tab (CBT) does not wrap backwards at the left margin, return
489  * a negative value at that point to simplify the loop.
490  */
491 #define LASTTAB(fr)	((fr > 0) ? ((fr - 1) / init_tabs) * init_tabs : -1)
492 
493 /* Note: we'd like to inline this for speed, but GNU C barfs on the attempt. */
494 
495 static int
496 relative_move(char *result, int from_y, int from_x, int to_y, int to_x, bool ovw)
497 /* move via local motions (cuu/cuu1/cud/cud1/cub1/cub/cuf1/cuf/vpa/hpa) */
498 {
499     int n, vcost = 0, hcost = 0;
500 
501     if (result)
502 	result[0] = '\0';
503 
504     if (to_y != from_y) {
505 	vcost = INFINITY;
506 
507 	if (row_address) {
508 	    if (result)
509 		(void) strcpy(result, tparm(row_address, to_y));
510 	    vcost = SP->_vpa_cost;
511 	}
512 
513 	if (to_y > from_y) {
514 	    n = (to_y - from_y);
515 
516 	    if (parm_down_cursor && SP->_cud_cost < vcost) {
517 		if (result)
518 		    (void) strcpy(result, tparm(parm_down_cursor, n));
519 		vcost = SP->_cud_cost;
520 	    }
521 
522 	    if (cursor_down && (n * SP->_cud1_cost < vcost)) {
523 		if (result)
524 		    result[0] = '\0';
525 		vcost = repeated_append(0, SP->_cud1_cost, n, result, cursor_down);
526 	    }
527 	} else {		/* (to_y < from_y) */
528 	    n = (from_y - to_y);
529 
530 	    if (parm_up_cursor && SP->_cup_cost < vcost) {
531 		if (result)
532 		    (void) strcpy(result, tparm(parm_up_cursor, n));
533 		vcost = SP->_cup_cost;
534 	    }
535 
536 	    if (cursor_up && (n * SP->_cuu1_cost < vcost)) {
537 		if (result)
538 		    result[0] = '\0';
539 		vcost = repeated_append(0, SP->_cuu1_cost, n, result, cursor_up);
540 	    }
541 	}
542 
543 	if (vcost == INFINITY)
544 	    return (INFINITY);
545     }
546 
547     if (result)
548 	result += strlen(result);
549 
550     if (to_x != from_x) {
551 	char str[OPT_SIZE];
552 
553 	hcost = INFINITY;
554 
555 	if (column_address) {
556 	    if (result)
557 		(void) strcpy(result, tparm(column_address, to_x));
558 	    hcost = SP->_hpa_cost;
559 	}
560 
561 	if (to_x > from_x) {
562 	    n = to_x - from_x;
563 
564 	    if (parm_right_cursor && SP->_cuf_cost < hcost) {
565 		if (result)
566 		    (void) strcpy(result, tparm(parm_right_cursor, n));
567 		hcost = SP->_cuf_cost;
568 	    }
569 
570 	    if (cursor_right) {
571 		int lhcost = 0;
572 
573 		str[0] = '\0';
574 
575 #if USE_HARD_TABS
576 		/* use hard tabs, if we have them, to do as much as possible */
577 		if (init_tabs > 0 && tab) {
578 		    int nxt, fr;
579 
580 		    for (fr = from_x; (nxt = NEXTTAB(fr)) <= to_x; fr = nxt) {
581 			lhcost = repeated_append(lhcost, SP->_ht_cost, 1,
582 			    str, tab);
583 			if (lhcost == INFINITY)
584 			    break;
585 		    }
586 
587 		    n = to_x - fr;
588 		    from_x = fr;
589 		}
590 #endif /* USE_HARD_TABS */
591 
592 #if defined(REAL_ATTR) && defined(WANT_CHAR)
593 #ifdef BSD_TPUTS
594 		/*
595 		 * If we're allowing BSD-style padding in tputs, don't generate
596 		 * a string with a leading digit.  Otherwise, that will be
597 		 * interpreted as a padding value rather than sent to the
598 		 * screen.
599 		 */
600 		if (ovw
601 		    && n > 0
602 		    && vcost == 0
603 		    && str[0] == '\0'
604 		    && isdigit(TextOf(WANT_CHAR(to_y, from_x))))
605 		    ovw = FALSE;
606 #endif
607 		/*
608 		 * If we have no attribute changes, overwrite is cheaper.
609 		 * Note: must suppress this by passing in ovw = FALSE whenever
610 		 * WANT_CHAR would return invalid data.  In particular, this
611 		 * is true between the time a hardware scroll has been done
612 		 * and the time the structure WANT_CHAR would access has been
613 		 * updated.
614 		 */
615 		if (ovw) {
616 		    int i;
617 
618 		    for (i = 0; i < n; i++)
619 			if ((WANT_CHAR(to_y, from_x + i) & A_ATTRIBUTES) != CURRENT_ATTR) {
620 			    ovw = FALSE;
621 			    break;
622 			}
623 		}
624 		if (ovw) {
625 		    char *sp;
626 		    int i;
627 
628 		    sp = str + strlen(str);
629 
630 		    for (i = 0; i < n; i++)
631 			*sp++ = WANT_CHAR(to_y, from_x + i);
632 		    *sp = '\0';
633 		    lhcost += n * SP->_char_padding;
634 		} else
635 #endif /* defined(REAL_ATTR) && defined(WANT_CHAR) */
636 		{
637 		    lhcost = repeated_append(lhcost, SP->_cuf1_cost, n, str, cursor_right);
638 		}
639 
640 		if (lhcost < hcost) {
641 		    if (result)
642 			(void) strcpy(result, str);
643 		    hcost = lhcost;
644 		}
645 	    }
646 	} else {		/* (to_x < from_x) */
647 	    n = from_x - to_x;
648 
649 	    if (parm_left_cursor && SP->_cub_cost < hcost) {
650 		if (result)
651 		    (void) strcpy(result, tparm(parm_left_cursor, n));
652 		hcost = SP->_cub_cost;
653 	    }
654 
655 	    if (cursor_left) {
656 		int lhcost = 0;
657 
658 		str[0] = '\0';
659 
660 #if USE_HARD_TABS
661 		if (init_tabs > 0 && back_tab) {
662 		    int nxt, fr;
663 
664 		    for (fr = from_x; (nxt = LASTTAB(fr)) >= to_x; fr = nxt) {
665 			lhcost = repeated_append(lhcost, SP->_cbt_cost, 1,
666 			    str, back_tab);
667 			if (lhcost == INFINITY)
668 			    break;
669 		    }
670 
671 		    n = fr - to_x;
672 		}
673 #endif /* USE_HARD_TABS */
674 
675 		lhcost = repeated_append(lhcost, SP->_cub1_cost, n, str, cursor_left);
676 
677 		if (lhcost < hcost) {
678 		    if (result)
679 			(void) strcpy(result, str);
680 		    hcost = lhcost;
681 		}
682 	    }
683 	}
684 
685 	if (hcost == INFINITY)
686 	    return (INFINITY);
687     }
688 
689     return (vcost + hcost);
690 }
691 #endif /* !NO_OPTIMIZE */
692 
693 /*
694  * With the machinery set up above, it's conceivable that
695  * onscreen_mvcur could be modified into a recursive function that does
696  * an alpha-beta search of motion space, as though it were a chess
697  * move tree, with the weight function being boolean and the search
698  * depth equated to length of string.  However, this would jack up the
699  * computation cost a lot, especially on terminals without a cup
700  * capability constraining the search tree depth.  So we settle for
701  * the simpler method below.
702  */
703 
704 static inline int
705 onscreen_mvcur(int yold, int xold, int ynew, int xnew, bool ovw)
706 /* onscreen move from (yold, xold) to (ynew, xnew) */
707 {
708     char use[OPT_SIZE], *sp;
709     int tactic = 0, newcost, usecost = INFINITY;
710     int t5_cr_cost;
711 
712 #if defined(MAIN) || defined(NCURSES_TEST)
713     struct timeval before, after;
714 
715     gettimeofday(&before, NULL);
716 #endif /* MAIN */
717 
718     /* tactic #0: use direct cursor addressing */
719     sp = tparm(SP->_address_cursor, ynew, xnew);
720     if (sp) {
721 	tactic = 0;
722 	(void) strcpy(use, sp);
723 	usecost = SP->_cup_cost;
724 
725 #if defined(TRACE) || defined(NCURSES_TEST)
726 	if (!(_nc_optimize_enable & OPTIMIZE_MVCUR))
727 	    goto nonlocal;
728 #endif /* TRACE */
729 
730 	/*
731 	 * We may be able to tell in advance that the full optimization
732 	 * will probably not be worth its overhead.  Also, don't try to
733 	 * use local movement if the current attribute is anything but
734 	 * A_NORMAL...there are just too many ways this can screw up
735 	 * (like, say, local-movement \n getting mapped to some obscure
736 	 * character because A_ALTCHARSET is on).
737 	 */
738 	if (yold == -1 || xold == -1 || NOT_LOCAL(yold, xold, ynew, xnew)) {
739 #if defined(MAIN) || defined(NCURSES_TEST)
740 	    if (!profiling) {
741 		(void) fputs("nonlocal\n", stderr);
742 		goto nonlocal;	/* always run the optimizer if profiling */
743 	    }
744 #else
745 	    goto nonlocal;
746 #endif /* MAIN */
747 	}
748     }
749 #ifndef NO_OPTIMIZE
750     /* tactic #1: use local movement */
751     if (yold != -1 && xold != -1
752 	&& ((newcost = relative_move(NULL, yold, xold, ynew, xnew, ovw)) != INFINITY)
753 	&& newcost < usecost) {
754 	tactic = 1;
755 	usecost = newcost;
756     }
757 
758     /* tactic #2: use carriage-return + local movement */
759     if (yold != -1 && carriage_return
760 	&& ((newcost = relative_move(NULL, yold, 0, ynew, xnew, ovw)) != INFINITY)
761 	&& SP->_cr_cost + newcost < usecost) {
762 	tactic = 2;
763 	usecost = SP->_cr_cost + newcost;
764     }
765 
766     /* tactic #3: use home-cursor + local movement */
767     if (cursor_home
768 	&& ((newcost = relative_move(NULL, 0, 0, ynew, xnew, ovw)) != INFINITY)
769 	&& SP->_home_cost + newcost < usecost) {
770 	tactic = 3;
771 	usecost = SP->_home_cost + newcost;
772     }
773 
774     /* tactic #4: use home-down + local movement */
775     if (cursor_to_ll
776 	&& ((newcost = relative_move(NULL, screen_lines - 1, 0, ynew, xnew,
777 		    ovw)) != INFINITY)
778 	&& SP->_ll_cost + newcost < usecost) {
779 	tactic = 4;
780 	usecost = SP->_ll_cost + newcost;
781     }
782 
783     /*
784      * tactic #5: use left margin for wrap to right-hand side,
785      * unless strange wrap behavior indicated by xenl might hose us.
786      */
787     t5_cr_cost = (xold > 0 ? SP->_cr_cost : 0);
788     if (auto_left_margin && !eat_newline_glitch
789 	&& yold > 0 && cursor_left
790 	&& ((newcost = relative_move(NULL, yold - 1, screen_columns - 1,
791 		    ynew, xnew, ovw)) != INFINITY)
792 	&& t5_cr_cost + SP->_cub1_cost + newcost < usecost) {
793 	tactic = 5;
794 	usecost = t5_cr_cost + SP->_cub1_cost + newcost;
795     }
796 
797     /*
798      * These cases are ordered by estimated relative frequency.
799      */
800     switch (tactic) {
801     case 1:
802 	(void) relative_move(use, yold, xold, ynew, xnew, ovw);
803 	break;
804     case 2:
805 	(void) strcpy(use, carriage_return);
806 	(void) relative_move(use + SP->_carriage_return_length,
807 	    yold, 0, ynew, xnew, ovw);
808 	break;
809     case 3:
810 	(void) strcpy(use, cursor_home);
811 	(void) relative_move(use + SP->_cursor_home_length,
812 	    0, 0, ynew, xnew, ovw);
813 	break;
814     case 4:
815 	(void) strcpy(use, cursor_to_ll);
816 	(void) relative_move(use + SP->_cursor_to_ll_length,
817 	    screen_lines - 1, 0, ynew, xnew, ovw);
818 	break;
819     case 5:
820 	use[0] = '\0';
821 	if (xold > 0)
822 	    (void) strcat(use, carriage_return);
823 	(void) strcat(use, cursor_left);
824 	(void) relative_move(use + strlen(use),
825 	    yold - 1, screen_columns - 1, ynew, xnew, ovw);
826 	break;
827     }
828 #endif /* !NO_OPTIMIZE */
829 
830 #if defined(MAIN) || defined(NCURSES_TEST)
831     gettimeofday(&after, NULL);
832     diff = after.tv_usec - before.tv_usec
833 	+ (after.tv_sec - before.tv_sec) * 1000000;
834     if (!profiling)
835 	(void) fprintf(stderr,
836 	    "onscreen: %d msec, %f 28.8Kbps char-equivalents\n",
837 	    (int) diff, diff / 288);
838 #endif /* MAIN */
839 
840   nonlocal:
841     if (usecost != INFINITY) {
842 	TPUTS_TRACE("mvcur");
843 	tputs(use, 1, _nc_outch);
844 	return (OK);
845     } else
846 	return (ERR);
847 }
848 
849 int
850 mvcur(int yold, int xold, int ynew, int xnew)
851 /* optimized cursor move from (yold, xold) to (ynew, xnew) */
852 {
853     TR(TRACE_MOVE, ("mvcur(%d,%d,%d,%d) called", yold, xold, ynew, xnew));
854 
855     if (yold == ynew && xold == xnew)
856 	return (OK);
857 
858     /*
859      * Most work here is rounding for terminal boundaries getting the
860      * column position implied by wraparound or the lack thereof and
861      * rolling up the screen to get ynew on the screen.
862      */
863 
864     if (xnew >= screen_columns) {
865 	ynew += xnew / screen_columns;
866 	xnew %= screen_columns;
867     }
868     if (xold >= screen_columns) {
869 	int l;
870 
871 	l = (xold + 1) / screen_columns;
872 	yold += l;
873 	if (yold >= screen_lines)
874 	    l -= (yold - screen_lines - 1);
875 
876 	while (l > 0) {
877 	    if (newline) {
878 		TPUTS_TRACE("newline");
879 		tputs(newline, 0, _nc_outch);
880 	    } else
881 		putchar('\n');
882 	    l--;
883 	    if (xold > 0) {
884 		if (carriage_return) {
885 		    TPUTS_TRACE("carriage_return");
886 		    tputs(carriage_return, 0, _nc_outch);
887 		} else
888 		    putchar('\r');
889 		xold = 0;
890 	    }
891 	}
892     }
893 
894     if (yold > screen_lines - 1)
895 	yold = screen_lines - 1;
896     if (ynew > screen_lines - 1)
897 	ynew = screen_lines - 1;
898 
899     /* destination location is on screen now */
900     return (onscreen_mvcur(yold, xold, ynew, xnew, TRUE));
901 }
902 
903 #if defined(TRACE) || defined(NCURSES_TEST)
904 int _nc_optimize_enable = OPTIMIZE_ALL;
905 #endif
906 
907 #if defined(MAIN) || defined(NCURSES_TEST)
908 /****************************************************************************
909  *
910  * Movement optimizer test code
911  *
912  ****************************************************************************/
913 
914 #include <tic.h>
915 #include <dump_entry.h>
916 
917 const char *_nc_progname = "mvcur";
918 
919 static unsigned long xmits;
920 
921 /* these override lib_tputs.c */
922 int
923 tputs(const char *string, int affcnt GCC_UNUSED, int (*outc) (int) GCC_UNUSED)
924 /* stub tputs() that dumps sequences in a visible form */
925 {
926     if (profiling)
927 	xmits += strlen(string);
928     else
929 	(void) fputs(_nc_visbuf(string), stdout);
930     return (OK);
931 }
932 
933 int
934 putp(const char *string)
935 {
936     return (tputs(string, 1, _nc_outch));
937 }
938 
939 int
940 _nc_outch(int ch)
941 {
942     putc(ch, stdout);
943     return OK;
944 }
945 
946 char PC = 0;			/* used by termcap library */
947 speed_t ospeed = 0;		/* used by termcap library */
948 int _nc_nulls_sent = 0;		/* used by 'tack' program */
949 
950 int
951 delay_output(int ms GCC_UNUSED)
952 {
953     return OK;
954 }
955 
956 static char tname[MAX_ALIAS];
957 
958 static void
959 load_term(void)
960 {
961     (void) setupterm(tname, STDOUT_FILENO, NULL);
962 }
963 
964 static int
965 roll(int n)
966 {
967     int i, j;
968 
969     i = (RAND_MAX / n) * n;
970     while ((j = rand()) >= i)
971 	continue;
972     return (j % n);
973 }
974 
975 int
976 main(int argc GCC_UNUSED, char *argv[]GCC_UNUSED)
977 {
978     (void) strcpy(tname, termname());
979     load_term();
980     _nc_setupscreen(lines, columns, stdout);
981     baudrate();
982 
983     _nc_mvcur_init();
984     NC_BUFFERED(FALSE);
985 
986     (void) puts("The mvcur tester.  Type ? for help");
987 
988     fputs("smcup:", stdout);
989     putchar('\n');
990 
991     for (;;) {
992 	int fy, fx, ty, tx, n, i;
993 	char buf[BUFSIZ], capname[BUFSIZ];
994 
995 	(void) fputs("> ", stdout);
996 	(void) fgets(buf, sizeof(buf), stdin);
997 
998 	if (buf[0] == '?') {
999 	    (void) puts("?                -- display this help message");
1000 	    (void)
1001 		puts("fy fx ty tx      -- (4 numbers) display (fy,fx)->(ty,tx) move");
1002 	    (void) puts("s[croll] n t b m -- display scrolling sequence");
1003 	    (void)
1004 		printf("r[eload]         -- reload terminal info for %s\n",
1005 		termname());
1006 	    (void)
1007 		puts("l[oad] <term>    -- load terminal info for type <term>");
1008 	    (void) puts("d[elete] <cap>   -- delete named capability");
1009 	    (void) puts("i[nspect]        -- display terminal capabilities");
1010 	    (void)
1011 		puts("c[ost]           -- dump cursor-optimization cost table");
1012 	    (void) puts("o[optimize]      -- toggle movement optimization");
1013 	    (void)
1014 		puts("t[orture] <num>  -- torture-test with <num> random moves");
1015 	    (void) puts("q[uit]           -- quit the program");
1016 	} else if (sscanf(buf, "%d %d %d %d", &fy, &fx, &ty, &tx) == 4) {
1017 	    struct timeval before, after;
1018 
1019 	    putchar('"');
1020 
1021 	    gettimeofday(&before, NULL);
1022 	    mvcur(fy, fx, ty, tx);
1023 	    gettimeofday(&after, NULL);
1024 
1025 	    printf("\" (%ld msec)\n",
1026 		(long) (after.tv_usec - before.tv_usec + (after.tv_sec -
1027 			before.tv_sec) * 1000000));
1028 	} else if (sscanf(buf, "s %d %d %d %d", &fy, &fx, &ty, &tx) == 4) {
1029 	    struct timeval before, after;
1030 
1031 	    putchar('"');
1032 
1033 	    gettimeofday(&before, NULL);
1034 	    _nc_scrolln(fy, fx, ty, tx);
1035 	    gettimeofday(&after, NULL);
1036 
1037 	    printf("\" (%ld msec)\n",
1038 		(long) (after.tv_usec - before.tv_usec + (after.tv_sec -
1039 			before.tv_sec) * 1000000));
1040 	} else if (buf[0] == 'r') {
1041 	    (void) strcpy(tname, termname());
1042 	    load_term();
1043 	} else if (sscanf(buf, "l %s", tname) == 1) {
1044 	    load_term();
1045 	} else if (sscanf(buf, "d %s", capname) == 1) {
1046 	    struct name_table_entry const *np = _nc_find_entry(capname,
1047 		_nc_info_hash_table);
1048 
1049 	    if (np == NULL)
1050 		(void) printf("No such capability as \"%s\"\n", capname);
1051 	    else {
1052 		switch (np->nte_type) {
1053 		case BOOLEAN:
1054 		    cur_term->type.Booleans[np->nte_index] = FALSE;
1055 		    (void)
1056 			printf("Boolean capability `%s' (%d) turned off.\n",
1057 			np->nte_name, np->nte_index);
1058 		    break;
1059 
1060 		case NUMBER:
1061 		    cur_term->type.Numbers[np->nte_index] = ABSENT_NUMERIC;
1062 		    (void) printf("Number capability `%s' (%d) set to -1.\n",
1063 			np->nte_name, np->nte_index);
1064 		    break;
1065 
1066 		case STRING:
1067 		    cur_term->type.Strings[np->nte_index] = ABSENT_STRING;
1068 		    (void) printf("String capability `%s' (%d) deleted.\n",
1069 			np->nte_name, np->nte_index);
1070 		    break;
1071 		}
1072 	    }
1073 	} else if (buf[0] == 'i') {
1074 	    dump_init((char *) NULL, F_TERMINFO, S_TERMINFO, 70, 0, FALSE);
1075 	    dump_entry(&cur_term->type, FALSE, TRUE, 0);
1076 	    putchar('\n');
1077 	} else if (buf[0] == 'o') {
1078 	    if (_nc_optimize_enable & OPTIMIZE_MVCUR) {
1079 		_nc_optimize_enable &= ~OPTIMIZE_MVCUR;
1080 		(void) puts("Optimization is now off.");
1081 	    } else {
1082 		_nc_optimize_enable |= OPTIMIZE_MVCUR;
1083 		(void) puts("Optimization is now on.");
1084 	    }
1085 	}
1086 	/*
1087 	 * You can use the `t' test to profile and tune the movement
1088 	 * optimizer.  Use iteration values in three digits or more.
1089 	 * At above 5000 iterations the profile timing averages are stable
1090 	 * to within a millisecond or three.
1091 	 *
1092 	 * The `overhead' field of the report will help you pick a
1093 	 * COMPUTE_OVERHEAD figure appropriate for your processor and
1094 	 * expected line speed.  The `total estimated time' is
1095 	 * computation time plus a character-transmission time
1096 	 * estimate computed from the number of transmits and the baud
1097 	 * rate.
1098 	 *
1099 	 * Use this together with the `o' command to get a read on the
1100 	 * optimizer's effectiveness.  Compare the total estimated times
1101 	 * for `t' runs of the same length in both optimized and un-optimized
1102 	 * modes.  As long as the optimized times are less, the optimizer
1103 	 * is winning.
1104 	 */
1105 	else if (sscanf(buf, "t %d", &n) == 1) {
1106 	    float cumtime = 0, perchar;
1107 	    int speeds[] =
1108 	    {2400, 9600, 14400, 19200, 28800, 38400, 0};
1109 
1110 	    srand((unsigned) (getpid() + time((time_t *) 0)));
1111 	    profiling = TRUE;
1112 	    xmits = 0;
1113 	    for (i = 0; i < n; i++) {
1114 		/*
1115 		 * This does a move test between two random locations,
1116 		 * Random moves probably short-change the optimizer,
1117 		 * which will work better on the short moves probably
1118 		 * typical of doupdate()'s usage pattern.  Still,
1119 		 * until we have better data...
1120 		 */
1121 #ifdef FIND_COREDUMP
1122 		int from_y = roll(lines);
1123 		int to_y = roll(lines);
1124 		int from_x = roll(columns);
1125 		int to_x = roll(columns);
1126 
1127 		printf("(%d,%d) -> (%d,%d)\n", from_y, from_x, to_y, to_x);
1128 		mvcur(from_y, from_x, to_y, to_x);
1129 #else
1130 		mvcur(roll(lines), roll(columns), roll(lines), roll(columns));
1131 #endif /* FIND_COREDUMP */
1132 		if (diff)
1133 		    cumtime += diff;
1134 	    }
1135 	    profiling = FALSE;
1136 
1137 	    /*
1138 	     * Average milliseconds per character optimization time.
1139 	     * This is the key figure to watch when tuning the optimizer.
1140 	     */
1141 	    perchar = cumtime / n;
1142 
1143 	    (void) printf("%d moves (%ld chars) in %d msec, %f msec each:\n",
1144 		n, xmits, (int) cumtime, perchar);
1145 
1146 	    for (i = 0; speeds[i]; i++) {
1147 		/*
1148 		 * Total estimated time for the moves, computation and
1149 		 * transmission both. Transmission time is an estimate
1150 		 * assuming 9 bits/char, 8 bits + 1 stop bit.
1151 		 */
1152 		float totalest = cumtime + xmits * 9 * 1e6 / speeds[i];
1153 
1154 		/*
1155 		 * Per-character optimization overhead in character transmits
1156 		 * at the current speed.  Round this to the nearest integer
1157 		 * to figure COMPUTE_OVERHEAD for the speed.
1158 		 */
1159 		float overhead = speeds[i] * perchar / 1e6;
1160 
1161 		(void)
1162 		    printf("%6d bps: %3.2f char-xmits overhead; total estimated time %15.2f\n",
1163 		    speeds[i], overhead, totalest);
1164 	    }
1165 	} else if (buf[0] == 'c') {
1166 	    (void) printf("char padding: %d\n", SP->_char_padding);
1167 	    (void) printf("cr cost: %d\n", SP->_cr_cost);
1168 	    (void) printf("cup cost: %d\n", SP->_cup_cost);
1169 	    (void) printf("home cost: %d\n", SP->_home_cost);
1170 	    (void) printf("ll cost: %d\n", SP->_ll_cost);
1171 #if USE_HARD_TABS
1172 	    (void) printf("ht cost: %d\n", SP->_ht_cost);
1173 	    (void) printf("cbt cost: %d\n", SP->_cbt_cost);
1174 #endif /* USE_HARD_TABS */
1175 	    (void) printf("cub1 cost: %d\n", SP->_cub1_cost);
1176 	    (void) printf("cuf1 cost: %d\n", SP->_cuf1_cost);
1177 	    (void) printf("cud1 cost: %d\n", SP->_cud1_cost);
1178 	    (void) printf("cuu1 cost: %d\n", SP->_cuu1_cost);
1179 	    (void) printf("cub cost: %d\n", SP->_cub_cost);
1180 	    (void) printf("cuf cost: %d\n", SP->_cuf_cost);
1181 	    (void) printf("cud cost: %d\n", SP->_cud_cost);
1182 	    (void) printf("cuu cost: %d\n", SP->_cuu_cost);
1183 	    (void) printf("hpa cost: %d\n", SP->_hpa_cost);
1184 	    (void) printf("vpa cost: %d\n", SP->_vpa_cost);
1185 	} else if (buf[0] == 'x' || buf[0] == 'q')
1186 	    break;
1187 	else
1188 	    (void) puts("Invalid command.");
1189     }
1190 
1191     (void) fputs("rmcup:", stdout);
1192     _nc_mvcur_wrap();
1193     putchar('\n');
1194 
1195     return (0);
1196 }
1197 
1198 #endif /* MAIN */
1199 
1200 /* lib_mvcur.c ends here */
1201