1/* $OpenBSD: hashmap.c,v 1.9 2023/10/17 09:52:09 nicm Exp $ */ 2 3/**************************************************************************** 4 * Copyright 2019-2020,2023 Thomas E. Dickey * 5 * Copyright 1998-2015,2016 Free Software Foundation, Inc. * 6 * * 7 * Permission is hereby granted, free of charge, to any person obtaining a * 8 * copy of this software and associated documentation files (the * 9 * "Software"), to deal in the Software without restriction, including * 10 * without limitation the rights to use, copy, modify, merge, publish, * 11 * distribute, distribute with modifications, sublicense, and/or sell * 12 * copies of the Software, and to permit persons to whom the Software is * 13 * furnished to do so, subject to the following conditions: * 14 * * 15 * The above copyright notice and this permission notice shall be included * 16 * in all copies or substantial portions of the Software. * 17 * * 18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * 19 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * 20 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * 21 * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, * 22 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR * 23 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR * 24 * THE USE OR OTHER DEALINGS IN THE SOFTWARE. * 25 * * 26 * Except as contained in this notice, the name(s) of the above copyright * 27 * holders shall not be used in advertising or otherwise to promote the * 28 * sale, use or other dealings in this Software without prior written * 29 * authorization. * 30 ****************************************************************************/ 31 32/**************************************************************************** 33 * Author: Zeyd M. Ben-Halim <zmbenhal@netcom.com> 1992,1995 * 34 * and: Eric S. Raymond <esr@snark.thyrsus.com> * 35 ****************************************************************************/ 36 37/****************************************************************************** 38 39NAME 40 hashmap.c -- fill in scramble vector based on text hashes 41 42SYNOPSIS 43 void _nc_hash_map(void) 44 45DESCRIPTION: 46 This code attempts to recognize pairs of old and new lines in the physical 47and virtual screens. When a line pair is recognized, the old line index is 48placed in the oldindex member of the virtual screen line, to be used by the 49vertical-motion optimizer portion of the update logic (see hardscroll.c). 50 51 Line pairs are recognized by applying a modified Heckel's algorithm, 52sped up by hashing. If a line hash is unique in both screens, those 53lines must be a pair. Then if the lines just before or after the pair 54are the same or similar, they are a pair too. 55 56 We don't worry about false pairs produced by hash collisions, on the 57assumption that such cases are rare and will only make the latter stages 58of update less efficient, not introduce errors. 59 60HOW TO TEST THIS: 61 62Use the following production: 63 64hashmap: hashmap.c 65 $(CC) -g -DHASHDEBUG hashmap.c hardscroll.c ../objects/lib_trace.o -o hashmap 66 67AUTHOR 68 Eric S. Raymond <esr@snark.thyrsus.com>, May 1996 69 Bug fixes and improvements by Alexander V. Lukyanov <lav@yars.free.net>, 1997 70 71*****************************************************************************/ 72 73#include <curses.priv.h> 74 75#ifndef CUR 76#define CUR SP_TERMTYPE 77#endif 78 79MODULE_ID("$Id: hashmap.c,v 1.9 2023/10/17 09:52:09 nicm Exp $") 80 81#ifdef HASHDEBUG 82 83# define _tracef printf 84# undef TR 85# ifdef TRACE 86# define TR(n, a) if (_nc_tracing & (n)) { _tracef a ; putchar('\n'); } 87# else 88# define TR(n, a) { _tracef a ; putchar('\n'); } 89# endif 90# undef screen_lines 91# define screen_lines(sp) MAXLINES 92# define TEXTWIDTH(sp) 1 93static int oldnums[MAXLINES], reallines[MAXLINES]; 94static NCURSES_CH_T oldtext[MAXLINES][TEXTWIDTH(sp)]; 95static NCURSES_CH_T newtext[MAXLINES][TEXTWIDTH(sp)]; 96# define OLDNUM(sp,n) oldnums[n] 97# define OLDTEXT(sp,n) oldtext[n] 98# define NEWTEXT(sp,m) newtext[m] 99# define PENDING(sp,n) 1 100 101#else /* !HASHDEBUG */ 102 103# define OLDNUM(sp,n) (sp)->_oldnum_list[n] 104# define OLDTEXT(sp,n) CurScreen(sp)->_line[n].text 105# define NEWTEXT(sp,m) NewScreen(sp)->_line[m].text 106# define TEXTWIDTH(sp) (CurScreen(sp)->_maxx + 1) 107# define PENDING(sp,n) (NewScreen(sp)->_line[n].firstchar != _NOCHANGE) 108 109#endif /* !HASHDEBUG */ 110 111#define oldhash(sp) ((sp)->oldhash) 112#define newhash(sp) ((sp)->newhash) 113#define hashtab(sp) ((sp)->hashtab) 114#define lines_alloc(sp) ((sp)->hashtab_len) 115 116#if USE_WIDEC_SUPPORT 117#define HASH_VAL(ch) (ch.chars[0]) 118#else 119#define HASH_VAL(ch) (ch) 120#endif 121 122static const NCURSES_CH_T blankchar = NewChar(BLANK_TEXT); 123 124static NCURSES_INLINE unsigned long 125hash(SCREEN *sp, NCURSES_CH_T *text) 126{ 127 int i; 128 NCURSES_CH_T ch; 129 unsigned long result = 0; 130 (void) sp; 131 132 for (i = TEXTWIDTH(sp); i > 0; i--) { 133 ch = *text++; 134 result += (result << 5) + (unsigned long) HASH_VAL(ch); 135 } 136 return result; 137} 138 139/* approximate update cost */ 140static int 141update_cost(SCREEN *sp, NCURSES_CH_T *from, NCURSES_CH_T *to) 142{ 143 int cost = 0; 144 int i; 145 (void) sp; 146 147 for (i = TEXTWIDTH(sp); i > 0; i--, from++, to++) 148 if (!(CharEq(*from, *to))) 149 cost++; 150 151 return cost; 152} 153 154static int 155update_cost_from_blank(SCREEN *sp, NCURSES_CH_T *to) 156{ 157 int cost = 0; 158 int i; 159 NCURSES_CH_T blank = blankchar; 160 (void) sp; 161 162 if (back_color_erase) 163 SetPair(blank, GetPair(stdscr->_nc_bkgd)); 164 165 for (i = TEXTWIDTH(sp); i > 0; i--, to++) 166 if (!(CharEq(blank, *to))) 167 cost++; 168 169 return cost; 170} 171 172/* 173 * Returns true when moving line 'from' to line 'to' seems to be cost 174 * effective. 'blank' indicates whether the line 'to' would become blank. 175 */ 176static NCURSES_INLINE bool 177cost_effective(SCREEN *sp, const int from, const int to, const int blank) 178{ 179 int new_from; 180 181 if (from == to) 182 return FALSE; 183 184 new_from = OLDNUM(sp, from); 185 if (new_from == _NEWINDEX) 186 new_from = from; 187 188 /* 189 * On the left side of >= is the cost before moving; 190 * on the right side -- cost after moving. 191 */ 192 return (((blank ? update_cost_from_blank(sp, NEWTEXT(sp, to)) 193 : update_cost(sp, OLDTEXT(sp, to), NEWTEXT(sp, to))) 194 + update_cost(sp, OLDTEXT(sp, new_from), NEWTEXT(sp, from))) 195 >= ((new_from == from ? update_cost_from_blank(sp, NEWTEXT(sp, from)) 196 : update_cost(sp, OLDTEXT(sp, new_from), NEWTEXT(sp, from))) 197 + update_cost(sp, OLDTEXT(sp, from), NEWTEXT(sp, to)))) 198 ? TRUE : FALSE; 199} 200 201static void 202grow_hunks(SCREEN *sp) 203{ 204 int back_limit; /* limits for cells to fill */ 205 int back_ref_limit; /* limit for references */ 206 int i; 207 int next_hunk; 208 209 /* 210 * This is tricky part. We have unique pairs to use as anchors. 211 * Use these to deduce the presence of spans of identical lines. 212 */ 213 back_limit = 0; 214 back_ref_limit = 0; 215 216 i = 0; 217 while (i < screen_lines(sp) && OLDNUM(sp, i) == _NEWINDEX) 218 i++; 219 for (; i < screen_lines(sp); i = next_hunk) { 220 int forward_limit; 221 int forward_ref_limit; 222 int end; 223 int start = i; 224 int shift = OLDNUM(sp, i) - i; 225 226 /* get forward limit */ 227 i = start + 1; 228 while (i < screen_lines(sp) 229 && OLDNUM(sp, i) != _NEWINDEX 230 && OLDNUM(sp, i) - i == shift) 231 i++; 232 end = i; 233 while (i < screen_lines(sp) && OLDNUM(sp, i) == _NEWINDEX) 234 i++; 235 next_hunk = i; 236 forward_limit = i; 237 if (i >= screen_lines(sp) || OLDNUM(sp, i) >= i) 238 forward_ref_limit = i; 239 else 240 forward_ref_limit = OLDNUM(sp, i); 241 242 i = start - 1; 243 /* grow back */ 244 if (shift < 0) 245 back_limit = back_ref_limit + (-shift); 246 while (i >= back_limit) { 247 if (newhash(sp)[i] == oldhash(sp)[i + shift] 248 || cost_effective(sp, i + shift, i, shift < 0)) { 249 OLDNUM(sp, i) = i + shift; 250 TR(TRACE_UPDATE | TRACE_MOVE, 251 ("connected new line %d to old line %d (backward continuation)", 252 i, i + shift)); 253 } else { 254 TR(TRACE_UPDATE | TRACE_MOVE, 255 ("not connecting new line %d to old line %d (backward continuation)", 256 i, i + shift)); 257 break; 258 } 259 i--; 260 } 261 262 i = end; 263 /* grow forward */ 264 if (shift > 0) 265 forward_limit = forward_ref_limit - shift; 266 while (i < forward_limit) { 267 if (newhash(sp)[i] == oldhash(sp)[i + shift] 268 || cost_effective(sp, i + shift, i, shift > 0)) { 269 OLDNUM(sp, i) = i + shift; 270 TR(TRACE_UPDATE | TRACE_MOVE, 271 ("connected new line %d to old line %d (forward continuation)", 272 i, i + shift)); 273 } else { 274 TR(TRACE_UPDATE | TRACE_MOVE, 275 ("not connecting new line %d to old line %d (forward continuation)", 276 i, i + shift)); 277 break; 278 } 279 i++; 280 } 281 282 back_ref_limit = back_limit = i; 283 if (shift > 0) 284 back_ref_limit += shift; 285 } 286} 287 288NCURSES_EXPORT(void) 289NCURSES_SP_NAME(_nc_hash_map) (NCURSES_SP_DCL0) 290{ 291 HASHMAP *hsp; 292 register int i; 293 294 if (screen_lines(SP_PARM) > lines_alloc(SP_PARM)) { 295 if (hashtab(SP_PARM)) 296 free(hashtab(SP_PARM)); 297 hashtab(SP_PARM) = typeMalloc(HASHMAP, 298 ((size_t) screen_lines(SP_PARM) + 1) * 2); 299 if (!hashtab(SP_PARM)) { 300 if (oldhash(SP_PARM)) { 301 FreeAndNull(oldhash(SP_PARM)); 302 } 303 lines_alloc(SP_PARM) = 0; 304 return; 305 } 306 lines_alloc(SP_PARM) = screen_lines(SP_PARM); 307 } 308 309 if (oldhash(SP_PARM) && newhash(SP_PARM)) { 310 /* re-hash only changed lines */ 311 for (i = 0; i < screen_lines(SP_PARM); i++) { 312 if (PENDING(SP_PARM, i)) 313 newhash(SP_PARM)[i] = hash(SP_PARM, NEWTEXT(SP_PARM, i)); 314 } 315 } else { 316 /* re-hash all */ 317 if (oldhash(SP_PARM) == 0) 318 oldhash(SP_PARM) = typeCalloc(unsigned long, 319 (size_t) screen_lines(SP_PARM)); 320 if (newhash(SP_PARM) == 0) 321 newhash(SP_PARM) = typeCalloc(unsigned long, 322 (size_t) screen_lines(SP_PARM)); 323 if (!oldhash(SP_PARM) || !newhash(SP_PARM)) { 324 FreeAndNull(oldhash(SP_PARM)); 325 FreeAndNull(newhash(SP_PARM)); 326 return; /* malloc failure */ 327 } 328 for (i = 0; i < screen_lines(SP_PARM); i++) { 329 newhash(SP_PARM)[i] = hash(SP_PARM, NEWTEXT(SP_PARM, i)); 330 oldhash(SP_PARM)[i] = hash(SP_PARM, OLDTEXT(SP_PARM, i)); 331 } 332 } 333 334#ifdef HASH_VERIFY 335 for (i = 0; i < screen_lines(SP_PARM); i++) { 336 if (newhash(SP_PARM)[i] != hash(SP_PARM, NEWTEXT(SP_PARM, i))) 337 fprintf(stderr, "error in newhash[%d]\n", i); 338 if (oldhash(SP_PARM)[i] != hash(SP_PARM, OLDTEXT(SP_PARM, i))) 339 fprintf(stderr, "error in oldhash[%d]\n", i); 340 } 341#endif 342 343 /* 344 * Set up and count line-hash values. 345 */ 346 memset(hashtab(SP_PARM), '\0', 347 sizeof(*(hashtab(SP_PARM))) 348 * ((size_t) screen_lines(SP_PARM) + 1) * 2); 349 for (i = 0; i < screen_lines(SP_PARM); i++) { 350 unsigned long hashval = oldhash(SP_PARM)[i]; 351 352 for (hsp = hashtab(SP_PARM); hsp->hashval; hsp++) 353 if (hsp->hashval == hashval) 354 break; 355 hsp->hashval = hashval; /* in case this is a new entry */ 356 hsp->oldcount++; 357 hsp->oldindex = i; 358 } 359 for (i = 0; i < screen_lines(SP_PARM); i++) { 360 unsigned long hashval = newhash(SP_PARM)[i]; 361 362 for (hsp = hashtab(SP_PARM); hsp->hashval; hsp++) 363 if (hsp->hashval == hashval) 364 break; 365 hsp->hashval = hashval; /* in case this is a new entry */ 366 hsp->newcount++; 367 hsp->newindex = i; 368 369 OLDNUM(SP_PARM, i) = _NEWINDEX; /* initialize old indices array */ 370 } 371 372 /* 373 * Mark line pairs corresponding to unique hash pairs. 374 * 375 * We don't mark lines with offset 0, because it can make fail 376 * extending hunks by cost_effective. Otherwise, it does not 377 * have any side effects. 378 */ 379 for (hsp = hashtab(SP_PARM); hsp->hashval; hsp++) 380 if (hsp->oldcount == 1 && hsp->newcount == 1 381 && hsp->oldindex != hsp->newindex) { 382 TR(TRACE_UPDATE | TRACE_MOVE, 383 ("new line %d is hash-identical to old line %d (unique)", 384 hsp->newindex, hsp->oldindex)); 385 OLDNUM(SP_PARM, hsp->newindex) = hsp->oldindex; 386 } 387 388 grow_hunks(SP_PARM); 389 390 /* 391 * Eliminate bad or impossible shifts -- this includes removing 392 * those hunks which could not grow because of conflicts, as well 393 * those which are to be moved too far, they are likely to destroy 394 * more than carry. 395 */ 396 for (i = 0; i < screen_lines(SP_PARM);) { 397 int start, shift, size; 398 399 while (i < screen_lines(SP_PARM) && OLDNUM(SP_PARM, i) == _NEWINDEX) 400 i++; 401 if (i >= screen_lines(SP_PARM)) 402 break; 403 start = i; 404 shift = OLDNUM(SP_PARM, i) - i; 405 i++; 406 while (i < screen_lines(SP_PARM) 407 && OLDNUM(SP_PARM, i) != _NEWINDEX 408 && OLDNUM(SP_PARM, i) - i == shift) 409 i++; 410 size = i - start; 411 if (size < 3 || size + min(size / 8, 2) < abs(shift)) { 412 while (start < i) { 413 OLDNUM(SP_PARM, start) = _NEWINDEX; 414 start++; 415 } 416 } 417 } 418 419 /* After clearing invalid hunks, try grow the rest. */ 420 grow_hunks(SP_PARM); 421} 422 423#if NCURSES_SP_FUNCS 424NCURSES_EXPORT(void) 425_nc_hash_map(void) 426{ 427 NCURSES_SP_NAME(_nc_hash_map) (CURRENT_SCREEN); 428} 429#endif 430 431NCURSES_EXPORT(void) 432NCURSES_SP_NAME(_nc_make_oldhash) (NCURSES_SP_DCLx int i) 433{ 434 if (oldhash(SP_PARM)) 435 oldhash(SP_PARM)[i] = hash(SP_PARM, OLDTEXT(SP_PARM, i)); 436} 437 438#if NCURSES_SP_FUNCS 439NCURSES_EXPORT(void) 440_nc_make_oldhash(int i) 441{ 442 NCURSES_SP_NAME(_nc_make_oldhash) (CURRENT_SCREEN, i); 443} 444#endif 445 446NCURSES_EXPORT(void) 447NCURSES_SP_NAME(_nc_scroll_oldhash) (NCURSES_SP_DCLx int n, int top, int bot) 448{ 449 size_t size; 450 int i; 451 452 if (!oldhash(SP_PARM)) 453 return; 454 455 size = sizeof(*(oldhash(SP_PARM))) * (size_t) (bot - top + 1 - abs(n)); 456 if (n > 0) { 457 memmove(oldhash(SP_PARM) + top, oldhash(SP_PARM) + top + n, size); 458 for (i = bot; i > bot - n; i--) 459 oldhash(SP_PARM)[i] = hash(SP_PARM, OLDTEXT(SP_PARM, i)); 460 } else { 461 memmove(oldhash(SP_PARM) + top - n, oldhash(SP_PARM) + top, size); 462 for (i = top; i < top - n; i++) 463 oldhash(SP_PARM)[i] = hash(SP_PARM, OLDTEXT(SP_PARM, i)); 464 } 465} 466 467#if NCURSES_SP_FUNCS 468NCURSES_EXPORT(void) 469_nc_scroll_oldhash(int n, int top, int bot) 470{ 471 NCURSES_SP_NAME(_nc_scroll_oldhash) (CURRENT_SCREEN, n, top, bot); 472} 473#endif 474 475#ifdef HASHDEBUG 476static void 477usage(void) 478{ 479 static const char *table[] = 480 { 481 "hashmap test-driver", 482 "", 483 "# comment", 484 "l get initial line number vector", 485 "n use following letters as text of new lines", 486 "o use following letters as text of old lines", 487 "d dump state of test arrays", 488 "h apply hash mapper and see scroll optimization", 489 "? this message" 490 }; 491 size_t n; 492 for (n = 0; n < sizeof(table) / sizeof(table[0]); n++) 493 fprintf(stderr, "%s\n", table[n]); 494} 495 496int 497main(int argc GCC_UNUSED, char *argv[]GCC_UNUSED) 498{ 499 char line[BUFSIZ], *st; 500 int n; 501 502 if (setupterm(NULL, fileno(stdout), (int *) 0) == ERR) 503 return EXIT_FAILURE; 504 (void) _nc_alloc_screen(); 505 506 for (n = 0; n < screen_lines(sp); n++) { 507 reallines[n] = n; 508 oldnums[n] = _NEWINDEX; 509 CharOf(oldtext[n][0]) = CharOf(newtext[n][0]) = '.'; 510 } 511 512 if (NC_ISATTY(fileno(stdin))) 513 usage(); 514 515#ifdef TRACE 516 _nc_tracing = TRACE_MOVE; 517#endif 518 for (;;) { 519 /* grab a test command */ 520 if (fgets(line, sizeof(line), stdin) == (char *) NULL) 521 break; 522 523 switch (line[0]) { 524 case '#': /* comment */ 525 (void) fputs(line, stderr); 526 break; 527 528 case 'l': /* get initial line number vector */ 529 for (n = 0; n < screen_lines(sp); n++) { 530 reallines[n] = n; 531 oldnums[n] = _NEWINDEX; 532 } 533 n = 0; 534 st = strtok(line, " "); 535 do { 536 oldnums[n++] = atoi(st); 537 } while 538 ((st = strtok((char *) NULL, " ")) != 0); 539 break; 540 541 case 'n': /* use following letters as text of new lines */ 542 for (n = 0; n < screen_lines(sp); n++) 543 CharOf(newtext[n][0]) = '.'; 544 for (n = 0; n < screen_lines(sp); n++) 545 if (line[n + 1] == '\n') 546 break; 547 else 548 CharOf(newtext[n][0]) = line[n + 1]; 549 break; 550 551 case 'o': /* use following letters as text of old lines */ 552 for (n = 0; n < screen_lines(sp); n++) 553 CharOf(oldtext[n][0]) = '.'; 554 for (n = 0; n < screen_lines(sp); n++) 555 if (line[n + 1] == '\n') 556 break; 557 else 558 CharOf(oldtext[n][0]) = line[n + 1]; 559 break; 560 561 case 'd': /* dump state of test arrays */ 562#ifdef TRACE 563 _nc_linedump(); 564#endif 565 (void) fputs("Old lines: [", stdout); 566 for (n = 0; n < screen_lines(sp); n++) 567 putchar(CharOf(oldtext[n][0])); 568 putchar(']'); 569 putchar('\n'); 570 (void) fputs("New lines: [", stdout); 571 for (n = 0; n < screen_lines(sp); n++) 572 putchar(CharOf(newtext[n][0])); 573 putchar(']'); 574 putchar('\n'); 575 break; 576 577 case 'h': /* apply hash mapper and see scroll optimization */ 578 _nc_hash_map(); 579 (void) fputs("Result:\n", stderr); 580#ifdef TRACE 581 _nc_linedump(); 582#endif 583 _nc_scroll_optimize(); 584 (void) fputs("Done.\n", stderr); 585 break; 586 default: 587 case '?': 588 usage(); 589 break; 590 } 591 } 592 exit_curses(EXIT_SUCCESS); 593} 594 595#endif /* HASHDEBUG */ 596 597/* hashmap.c ends here */ 598