1 /****************************************************************************
2 * Copyright 2019,2020 Thomas E. Dickey *
3 * Copyright 1998-2015,2016 Free Software Foundation, Inc. *
4 * *
5 * Permission is hereby granted, free of charge, to any person obtaining a *
6 * copy of this software and associated documentation files (the *
7 * "Software"), to deal in the Software without restriction, including *
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10 * copies of the Software, and to permit persons to whom the Software is *
11 * furnished to do so, subject to the following conditions: *
12 * *
13 * The above copyright notice and this permission notice shall be included *
14 * in all copies or substantial portions of the Software. *
15 * *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS *
17 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF *
18 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. *
19 * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, *
20 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR *
21 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR *
22 * THE USE OR OTHER DEALINGS IN THE SOFTWARE. *
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25 * holders shall not be used in advertising or otherwise to promote the *
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28 ****************************************************************************/
29
30 /****************************************************************************
31 * Author: Zeyd M. Ben-Halim <zmbenhal@netcom.com> 1992,1995 *
32 * and: Eric S. Raymond <esr@snark.thyrsus.com> *
33 ****************************************************************************/
34
35 /******************************************************************************
36
37 NAME
38 hashmap.c -- fill in scramble vector based on text hashes
39
40 SYNOPSIS
41 void _nc_hash_map(void)
42
43 DESCRIPTION:
44 This code attempts to recognize pairs of old and new lines in the physical
45 and virtual screens. When a line pair is recognized, the old line index is
46 placed in the oldindex member of the virtual screen line, to be used by the
47 vertical-motion optimizer portion of the update logic (see hardscroll.c).
48
49 Line pairs are recognized by applying a modified Heckel's algorithm,
50 sped up by hashing. If a line hash is unique in both screens, those
51 lines must be a pair. Then if the lines just before or after the pair
52 are the same or similar, they are a pair too.
53
54 We don't worry about false pairs produced by hash collisions, on the
55 assumption that such cases are rare and will only make the latter stages
56 of update less efficient, not introduce errors.
57
58 HOW TO TEST THIS:
59
60 Use the following production:
61
62 hashmap: hashmap.c
63 $(CC) -g -DHASHDEBUG hashmap.c hardscroll.c ../objects/lib_trace.o -o hashmap
64
65 AUTHOR
66 Eric S. Raymond <esr@snark.thyrsus.com>, May 1996
67 Bug fixes and improvements by Alexander V. Lukyanov <lav@yars.free.net>, 1997
68
69 *****************************************************************************/
70
71 #include <curses.priv.h>
72
73 #ifndef CUR
74 #define CUR SP_TERMTYPE
75 #endif
76
77 MODULE_ID("$Id: hashmap.c,v 1.69 2020/05/31 17:50:48 tom Exp $")
78
79 #ifdef HASHDEBUG
80
81 # define _tracef printf
82 # undef TR
83 # ifdef TRACE
84 # define TR(n, a) if (_nc_tracing & (n)) { _tracef a ; putchar('\n'); }
85 # else
86 # define TR(n, a) { _tracef a ; putchar('\n'); }
87 # endif
88 # undef screen_lines
89 # define screen_lines(sp) MAXLINES
90 # define TEXTWIDTH(sp) 1
91 static int oldnums[MAXLINES], reallines[MAXLINES];
92 static NCURSES_CH_T oldtext[MAXLINES][TEXTWIDTH(sp)];
93 static NCURSES_CH_T newtext[MAXLINES][TEXTWIDTH(sp)];
94 # define OLDNUM(sp,n) oldnums[n]
95 # define OLDTEXT(sp,n) oldtext[n]
96 # define NEWTEXT(sp,m) newtext[m]
97 # define PENDING(sp,n) 1
98
99 #else /* !HASHDEBUG */
100
101 # define OLDNUM(sp,n) (sp)->_oldnum_list[n]
102 # define OLDTEXT(sp,n) CurScreen(sp)->_line[n].text
103 # define NEWTEXT(sp,m) NewScreen(sp)->_line[m].text
104 # define TEXTWIDTH(sp) (CurScreen(sp)->_maxx + 1)
105 # define PENDING(sp,n) (NewScreen(sp)->_line[n].firstchar != _NOCHANGE)
106
107 #endif /* !HASHDEBUG */
108
109 #define oldhash(sp) ((sp)->oldhash)
110 #define newhash(sp) ((sp)->newhash)
111 #define hashtab(sp) ((sp)->hashtab)
112 #define lines_alloc(sp) ((sp)->hashtab_len)
113
114 #if USE_WIDEC_SUPPORT
115 #define HASH_VAL(ch) (ch.chars[0])
116 #else
117 #define HASH_VAL(ch) (ch)
118 #endif
119
120 static const NCURSES_CH_T blankchar = NewChar(BLANK_TEXT);
121
122 static NCURSES_INLINE unsigned long
hash(SCREEN * sp,NCURSES_CH_T * text)123 hash(SCREEN *sp, NCURSES_CH_T *text)
124 {
125 int i;
126 NCURSES_CH_T ch;
127 unsigned long result = 0;
128 (void) sp;
129
130 for (i = TEXTWIDTH(sp); i > 0; i--) {
131 ch = *text++;
132 result += (result << 5) + (unsigned long) HASH_VAL(ch);
133 }
134 return result;
135 }
136
137 /* approximate update cost */
138 static int
update_cost(SCREEN * sp,NCURSES_CH_T * from,NCURSES_CH_T * to)139 update_cost(SCREEN *sp, NCURSES_CH_T *from, NCURSES_CH_T *to)
140 {
141 int cost = 0;
142 int i;
143 (void) sp;
144
145 for (i = TEXTWIDTH(sp); i > 0; i--, from++, to++)
146 if (!(CharEq(*from, *to)))
147 cost++;
148
149 return cost;
150 }
151
152 static int
update_cost_from_blank(SCREEN * sp,NCURSES_CH_T * to)153 update_cost_from_blank(SCREEN *sp, NCURSES_CH_T *to)
154 {
155 int cost = 0;
156 int i;
157 NCURSES_CH_T blank = blankchar;
158 (void) sp;
159
160 if (back_color_erase)
161 SetPair(blank, GetPair(stdscr->_nc_bkgd));
162
163 for (i = TEXTWIDTH(sp); i > 0; i--, to++)
164 if (!(CharEq(blank, *to)))
165 cost++;
166
167 return cost;
168 }
169
170 /*
171 * Returns true when moving line 'from' to line 'to' seems to be cost
172 * effective. 'blank' indicates whether the line 'to' would become blank.
173 */
174 static NCURSES_INLINE bool
cost_effective(SCREEN * sp,const int from,const int to,const int blank)175 cost_effective(SCREEN *sp, const int from, const int to, const int blank)
176 {
177 int new_from;
178
179 if (from == to)
180 return FALSE;
181
182 new_from = OLDNUM(sp, from);
183 if (new_from == _NEWINDEX)
184 new_from = from;
185
186 /*
187 * On the left side of >= is the cost before moving;
188 * on the right side -- cost after moving.
189 */
190 return (((blank ? update_cost_from_blank(sp, NEWTEXT(sp, to))
191 : update_cost(sp, OLDTEXT(sp, to), NEWTEXT(sp, to)))
192 + update_cost(sp, OLDTEXT(sp, new_from), NEWTEXT(sp, from)))
193 >= ((new_from == from ? update_cost_from_blank(sp, NEWTEXT(sp, from))
194 : update_cost(sp, OLDTEXT(sp, new_from), NEWTEXT(sp, from)))
195 + update_cost(sp, OLDTEXT(sp, from), NEWTEXT(sp, to))))
196 ? TRUE : FALSE;
197 }
198
199 static void
grow_hunks(SCREEN * sp)200 grow_hunks(SCREEN *sp)
201 {
202 int back_limit; /* limits for cells to fill */
203 int back_ref_limit; /* limit for references */
204 int i;
205 int next_hunk;
206
207 /*
208 * This is tricky part. We have unique pairs to use as anchors.
209 * Use these to deduce the presence of spans of identical lines.
210 */
211 back_limit = 0;
212 back_ref_limit = 0;
213
214 i = 0;
215 while (i < screen_lines(sp) && OLDNUM(sp, i) == _NEWINDEX)
216 i++;
217 for (; i < screen_lines(sp); i = next_hunk) {
218 int forward_limit;
219 int forward_ref_limit;
220 int end;
221 int start = i;
222 int shift = OLDNUM(sp, i) - i;
223
224 /* get forward limit */
225 i = start + 1;
226 while (i < screen_lines(sp)
227 && OLDNUM(sp, i) != _NEWINDEX
228 && OLDNUM(sp, i) - i == shift)
229 i++;
230 end = i;
231 while (i < screen_lines(sp) && OLDNUM(sp, i) == _NEWINDEX)
232 i++;
233 next_hunk = i;
234 forward_limit = i;
235 if (i >= screen_lines(sp) || OLDNUM(sp, i) >= i)
236 forward_ref_limit = i;
237 else
238 forward_ref_limit = OLDNUM(sp, i);
239
240 i = start - 1;
241 /* grow back */
242 if (shift < 0)
243 back_limit = back_ref_limit + (-shift);
244 while (i >= back_limit) {
245 if (newhash(sp)[i] == oldhash(sp)[i + shift]
246 || cost_effective(sp, i + shift, i, shift < 0)) {
247 OLDNUM(sp, i) = i + shift;
248 TR(TRACE_UPDATE | TRACE_MOVE,
249 ("connected new line %d to old line %d (backward continuation)",
250 i, i + shift));
251 } else {
252 TR(TRACE_UPDATE | TRACE_MOVE,
253 ("not connecting new line %d to old line %d (backward continuation)",
254 i, i + shift));
255 break;
256 }
257 i--;
258 }
259
260 i = end;
261 /* grow forward */
262 if (shift > 0)
263 forward_limit = forward_ref_limit - shift;
264 while (i < forward_limit) {
265 if (newhash(sp)[i] == oldhash(sp)[i + shift]
266 || cost_effective(sp, i + shift, i, shift > 0)) {
267 OLDNUM(sp, i) = i + shift;
268 TR(TRACE_UPDATE | TRACE_MOVE,
269 ("connected new line %d to old line %d (forward continuation)",
270 i, i + shift));
271 } else {
272 TR(TRACE_UPDATE | TRACE_MOVE,
273 ("not connecting new line %d to old line %d (forward continuation)",
274 i, i + shift));
275 break;
276 }
277 i++;
278 }
279
280 back_ref_limit = back_limit = i;
281 if (shift > 0)
282 back_ref_limit += shift;
283 }
284 }
285
286 NCURSES_EXPORT(void)
NCURSES_SP_NAME(_nc_hash_map)287 NCURSES_SP_NAME(_nc_hash_map) (NCURSES_SP_DCL0)
288 {
289 HASHMAP *hsp;
290 register int i;
291
292 if (screen_lines(SP_PARM) > lines_alloc(SP_PARM)) {
293 if (hashtab(SP_PARM))
294 free(hashtab(SP_PARM));
295 hashtab(SP_PARM) = typeMalloc(HASHMAP,
296 ((size_t) screen_lines(SP_PARM) + 1) * 2);
297 if (!hashtab(SP_PARM)) {
298 if (oldhash(SP_PARM)) {
299 FreeAndNull(oldhash(SP_PARM));
300 }
301 lines_alloc(SP_PARM) = 0;
302 return;
303 }
304 lines_alloc(SP_PARM) = screen_lines(SP_PARM);
305 }
306
307 if (oldhash(SP_PARM) && newhash(SP_PARM)) {
308 /* re-hash only changed lines */
309 for (i = 0; i < screen_lines(SP_PARM); i++) {
310 if (PENDING(SP_PARM, i))
311 newhash(SP_PARM)[i] = hash(SP_PARM, NEWTEXT(SP_PARM, i));
312 }
313 } else {
314 /* re-hash all */
315 if (oldhash(SP_PARM) == 0)
316 oldhash(SP_PARM) = typeCalloc(unsigned long,
317 (size_t) screen_lines(SP_PARM));
318 if (newhash(SP_PARM) == 0)
319 newhash(SP_PARM) = typeCalloc(unsigned long,
320 (size_t) screen_lines(SP_PARM));
321 if (!oldhash(SP_PARM) || !newhash(SP_PARM))
322 return; /* malloc failure */
323 for (i = 0; i < screen_lines(SP_PARM); i++) {
324 newhash(SP_PARM)[i] = hash(SP_PARM, NEWTEXT(SP_PARM, i));
325 oldhash(SP_PARM)[i] = hash(SP_PARM, OLDTEXT(SP_PARM, i));
326 }
327 }
328
329 #ifdef HASH_VERIFY
330 for (i = 0; i < screen_lines(SP_PARM); i++) {
331 if (newhash(SP_PARM)[i] != hash(SP_PARM, NEWTEXT(SP_PARM, i)))
332 fprintf(stderr, "error in newhash[%d]\n", i);
333 if (oldhash(SP_PARM)[i] != hash(SP_PARM, OLDTEXT(SP_PARM, i)))
334 fprintf(stderr, "error in oldhash[%d]\n", i);
335 }
336 #endif
337
338 /*
339 * Set up and count line-hash values.
340 */
341 memset(hashtab(SP_PARM), '\0',
342 sizeof(*(hashtab(SP_PARM)))
343 * ((size_t) screen_lines(SP_PARM) + 1) * 2);
344 for (i = 0; i < screen_lines(SP_PARM); i++) {
345 unsigned long hashval = oldhash(SP_PARM)[i];
346
347 for (hsp = hashtab(SP_PARM); hsp->hashval; hsp++)
348 if (hsp->hashval == hashval)
349 break;
350 hsp->hashval = hashval; /* in case this is a new entry */
351 hsp->oldcount++;
352 hsp->oldindex = i;
353 }
354 for (i = 0; i < screen_lines(SP_PARM); i++) {
355 unsigned long hashval = newhash(SP_PARM)[i];
356
357 for (hsp = hashtab(SP_PARM); hsp->hashval; hsp++)
358 if (hsp->hashval == hashval)
359 break;
360 hsp->hashval = hashval; /* in case this is a new entry */
361 hsp->newcount++;
362 hsp->newindex = i;
363
364 OLDNUM(SP_PARM, i) = _NEWINDEX; /* initialize old indices array */
365 }
366
367 /*
368 * Mark line pairs corresponding to unique hash pairs.
369 *
370 * We don't mark lines with offset 0, because it can make fail
371 * extending hunks by cost_effective. Otherwise, it does not
372 * have any side effects.
373 */
374 for (hsp = hashtab(SP_PARM); hsp->hashval; hsp++)
375 if (hsp->oldcount == 1 && hsp->newcount == 1
376 && hsp->oldindex != hsp->newindex) {
377 TR(TRACE_UPDATE | TRACE_MOVE,
378 ("new line %d is hash-identical to old line %d (unique)",
379 hsp->newindex, hsp->oldindex));
380 OLDNUM(SP_PARM, hsp->newindex) = hsp->oldindex;
381 }
382
383 grow_hunks(SP_PARM);
384
385 /*
386 * Eliminate bad or impossible shifts -- this includes removing
387 * those hunks which could not grow because of conflicts, as well
388 * those which are to be moved too far, they are likely to destroy
389 * more than carry.
390 */
391 for (i = 0; i < screen_lines(SP_PARM);) {
392 int start, shift, size;
393
394 while (i < screen_lines(SP_PARM) && OLDNUM(SP_PARM, i) == _NEWINDEX)
395 i++;
396 if (i >= screen_lines(SP_PARM))
397 break;
398 start = i;
399 shift = OLDNUM(SP_PARM, i) - i;
400 i++;
401 while (i < screen_lines(SP_PARM)
402 && OLDNUM(SP_PARM, i) != _NEWINDEX
403 && OLDNUM(SP_PARM, i) - i == shift)
404 i++;
405 size = i - start;
406 if (size < 3 || size + min(size / 8, 2) < abs(shift)) {
407 while (start < i) {
408 OLDNUM(SP_PARM, start) = _NEWINDEX;
409 start++;
410 }
411 }
412 }
413
414 /* After clearing invalid hunks, try grow the rest. */
415 grow_hunks(SP_PARM);
416 }
417
418 #if NCURSES_SP_FUNCS
419 NCURSES_EXPORT(void)
_nc_hash_map(void)420 _nc_hash_map(void)
421 {
422 NCURSES_SP_NAME(_nc_hash_map) (CURRENT_SCREEN);
423 }
424 #endif
425
426 NCURSES_EXPORT(void)
NCURSES_SP_NAME(_nc_make_oldhash)427 NCURSES_SP_NAME(_nc_make_oldhash) (NCURSES_SP_DCLx int i)
428 {
429 if (oldhash(SP_PARM))
430 oldhash(SP_PARM)[i] = hash(SP_PARM, OLDTEXT(SP_PARM, i));
431 }
432
433 #if NCURSES_SP_FUNCS
434 NCURSES_EXPORT(void)
_nc_make_oldhash(int i)435 _nc_make_oldhash(int i)
436 {
437 NCURSES_SP_NAME(_nc_make_oldhash) (CURRENT_SCREEN, i);
438 }
439 #endif
440
441 NCURSES_EXPORT(void)
NCURSES_SP_NAME(_nc_scroll_oldhash)442 NCURSES_SP_NAME(_nc_scroll_oldhash) (NCURSES_SP_DCLx int n, int top, int bot)
443 {
444 size_t size;
445 int i;
446
447 if (!oldhash(SP_PARM))
448 return;
449
450 size = sizeof(*(oldhash(SP_PARM))) * (size_t) (bot - top + 1 - abs(n));
451 if (n > 0) {
452 memmove(oldhash(SP_PARM) + top, oldhash(SP_PARM) + top + n, size);
453 for (i = bot; i > bot - n; i--)
454 oldhash(SP_PARM)[i] = hash(SP_PARM, OLDTEXT(SP_PARM, i));
455 } else {
456 memmove(oldhash(SP_PARM) + top - n, oldhash(SP_PARM) + top, size);
457 for (i = top; i < top - n; i++)
458 oldhash(SP_PARM)[i] = hash(SP_PARM, OLDTEXT(SP_PARM, i));
459 }
460 }
461
462 #if NCURSES_SP_FUNCS
463 NCURSES_EXPORT(void)
_nc_scroll_oldhash(int n,int top,int bot)464 _nc_scroll_oldhash(int n, int top, int bot)
465 {
466 NCURSES_SP_NAME(_nc_scroll_oldhash) (CURRENT_SCREEN, n, top, bot);
467 }
468 #endif
469
470 #ifdef HASHDEBUG
471 static void
usage(void)472 usage(void)
473 {
474 static const char *table[] =
475 {
476 "hashmap test-driver",
477 "",
478 "# comment",
479 "l get initial line number vector",
480 "n use following letters as text of new lines",
481 "o use following letters as text of old lines",
482 "d dump state of test arrays",
483 "h apply hash mapper and see scroll optimization",
484 "? this message"
485 };
486 size_t n;
487 for (n = 0; n < sizeof(table) / sizeof(table[0]); n++)
488 fprintf(stderr, "%s\n", table[n]);
489 }
490
491 int
main(int argc GCC_UNUSED,char * argv[]GCC_UNUSED)492 main(int argc GCC_UNUSED, char *argv[]GCC_UNUSED)
493 {
494 char line[BUFSIZ], *st;
495 int n;
496
497 if (setupterm(NULL, fileno(stdout), (int *) 0) == ERR)
498 return EXIT_FAILURE;
499 (void) _nc_alloc_screen();
500
501 for (n = 0; n < screen_lines(sp); n++) {
502 reallines[n] = n;
503 oldnums[n] = _NEWINDEX;
504 CharOf(oldtext[n][0]) = CharOf(newtext[n][0]) = '.';
505 }
506
507 if (NC_ISATTY(fileno(stdin)))
508 usage();
509
510 #ifdef TRACE
511 _nc_tracing = TRACE_MOVE;
512 #endif
513 for (;;) {
514 /* grab a test command */
515 if (fgets(line, sizeof(line), stdin) == (char *) NULL)
516 break;
517
518 switch (line[0]) {
519 case '#': /* comment */
520 (void) fputs(line, stderr);
521 break;
522
523 case 'l': /* get initial line number vector */
524 for (n = 0; n < screen_lines(sp); n++) {
525 reallines[n] = n;
526 oldnums[n] = _NEWINDEX;
527 }
528 n = 0;
529 st = strtok(line, " ");
530 do {
531 oldnums[n++] = atoi(st);
532 } while
533 ((st = strtok((char *) NULL, " ")) != 0);
534 break;
535
536 case 'n': /* use following letters as text of new lines */
537 for (n = 0; n < screen_lines(sp); n++)
538 CharOf(newtext[n][0]) = '.';
539 for (n = 0; n < screen_lines(sp); n++)
540 if (line[n + 1] == '\n')
541 break;
542 else
543 CharOf(newtext[n][0]) = line[n + 1];
544 break;
545
546 case 'o': /* use following letters as text of old lines */
547 for (n = 0; n < screen_lines(sp); n++)
548 CharOf(oldtext[n][0]) = '.';
549 for (n = 0; n < screen_lines(sp); n++)
550 if (line[n + 1] == '\n')
551 break;
552 else
553 CharOf(oldtext[n][0]) = line[n + 1];
554 break;
555
556 case 'd': /* dump state of test arrays */
557 #ifdef TRACE
558 _nc_linedump();
559 #endif
560 (void) fputs("Old lines: [", stdout);
561 for (n = 0; n < screen_lines(sp); n++)
562 putchar(CharOf(oldtext[n][0]));
563 putchar(']');
564 putchar('\n');
565 (void) fputs("New lines: [", stdout);
566 for (n = 0; n < screen_lines(sp); n++)
567 putchar(CharOf(newtext[n][0]));
568 putchar(']');
569 putchar('\n');
570 break;
571
572 case 'h': /* apply hash mapper and see scroll optimization */
573 _nc_hash_map();
574 (void) fputs("Result:\n", stderr);
575 #ifdef TRACE
576 _nc_linedump();
577 #endif
578 _nc_scroll_optimize();
579 (void) fputs("Done.\n", stderr);
580 break;
581 default:
582 case '?':
583 usage();
584 break;
585 }
586 }
587 exit_curses(EXIT_SUCCESS);
588 }
589
590 #endif /* HASHDEBUG */
591
592 /* hashmap.c ends here */
593