1 /* tblcmp - table compression routines */ 2 3 /*- 4 * Copyright (c) 1990 The Regents of the University of California. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Vern Paxson. 9 * 10 * The United States Government has rights in this work pursuant 11 * to contract no. DE-AC03-76SF00098 between the United States 12 * Department of Energy and the University of California. 13 * 14 * Redistribution and use in source and binary forms with or without 15 * modification are permitted provided that: (1) source distributions retain 16 * this entire copyright notice and comment, and (2) distributions including 17 * binaries display the following acknowledgement: ``This product includes 18 * software developed by the University of California, Berkeley and its 19 * contributors'' in the documentation or other materials provided with the 20 * distribution and in all advertising materials mentioning features or use 21 * of this software. Neither the name of the University nor the names of 22 * its contributors may be used to endorse or promote products derived from 23 * this software without specific prior written permission. 24 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED 25 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF 26 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 27 */ 28 29 /* $Header: /home/daffy/u0/vern/flex/RCS/tblcmp.c,v 2.11 94/11/05 17:08:28 vern Exp $ */ 30 31 #include "flexdef.h" 32 33 34 /* declarations for functions that have forward references */ 35 36 void mkentry PROTO((register int*, int, int, int, int)); 37 void mkprot PROTO((int[], int, int)); 38 void mktemplate PROTO((int[], int, int)); 39 void mv2front PROTO((int)); 40 int tbldiff PROTO((int[], int, int[])); 41 42 43 /* bldtbl - build table entries for dfa state 44 * 45 * synopsis 46 * int state[numecs], statenum, totaltrans, comstate, comfreq; 47 * bldtbl( state, statenum, totaltrans, comstate, comfreq ); 48 * 49 * State is the statenum'th dfa state. It is indexed by equivalence class and 50 * gives the number of the state to enter for a given equivalence class. 51 * totaltrans is the total number of transitions out of the state. Comstate 52 * is that state which is the destination of the most transitions out of State. 53 * Comfreq is how many transitions there are out of State to Comstate. 54 * 55 * A note on terminology: 56 * "protos" are transition tables which have a high probability of 57 * either being redundant (a state processed later will have an identical 58 * transition table) or nearly redundant (a state processed later will have 59 * many of the same out-transitions). A "most recently used" queue of 60 * protos is kept around with the hope that most states will find a proto 61 * which is similar enough to be usable, and therefore compacting the 62 * output tables. 63 * "templates" are a special type of proto. If a transition table is 64 * homogeneous or nearly homogeneous (all transitions go to the same 65 * destination) then the odds are good that future states will also go 66 * to the same destination state on basically the same character set. 67 * These homogeneous states are so common when dealing with large rule 68 * sets that they merit special attention. If the transition table were 69 * simply made into a proto, then (typically) each subsequent, similar 70 * state will differ from the proto for two out-transitions. One of these 71 * out-transitions will be that character on which the proto does not go 72 * to the common destination, and one will be that character on which the 73 * state does not go to the common destination. Templates, on the other 74 * hand, go to the common state on EVERY transition character, and therefore 75 * cost only one difference. 76 */ 77 78 void bldtbl( state, statenum, totaltrans, comstate, comfreq ) 79 int state[], statenum, totaltrans, comstate, comfreq; 80 { 81 int extptr, extrct[2][CSIZE + 1]; 82 int mindiff, minprot, i, d; 83 84 /* If extptr is 0 then the first array of extrct holds the result 85 * of the "best difference" to date, which is those transitions 86 * which occur in "state" but not in the proto which, to date, 87 * has the fewest differences between itself and "state". If 88 * extptr is 1 then the second array of extrct hold the best 89 * difference. The two arrays are toggled between so that the 90 * best difference to date can be kept around and also a difference 91 * just created by checking against a candidate "best" proto. 92 */ 93 94 extptr = 0; 95 96 /* If the state has too few out-transitions, don't bother trying to 97 * compact its tables. 98 */ 99 100 if ( (totaltrans * 100) < (numecs * PROTO_SIZE_PERCENTAGE) ) 101 mkentry( state, numecs, statenum, JAMSTATE, totaltrans ); 102 103 else 104 { 105 /* "checkcom" is true if we should only check "state" against 106 * protos which have the same "comstate" value. 107 */ 108 int checkcom = 109 comfreq * 100 > totaltrans * CHECK_COM_PERCENTAGE; 110 111 minprot = firstprot; 112 mindiff = totaltrans; 113 114 if ( checkcom ) 115 { 116 /* Find first proto which has the same "comstate". */ 117 for ( i = firstprot; i != NIL; i = protnext[i] ) 118 if ( protcomst[i] == comstate ) 119 { 120 minprot = i; 121 mindiff = tbldiff( state, minprot, 122 extrct[extptr] ); 123 break; 124 } 125 } 126 127 else 128 { 129 /* Since we've decided that the most common destination 130 * out of "state" does not occur with a high enough 131 * frequency, we set the "comstate" to zero, assuring 132 * that if this state is entered into the proto list, 133 * it will not be considered a template. 134 */ 135 comstate = 0; 136 137 if ( firstprot != NIL ) 138 { 139 minprot = firstprot; 140 mindiff = tbldiff( state, minprot, 141 extrct[extptr] ); 142 } 143 } 144 145 /* We now have the first interesting proto in "minprot". If 146 * it matches within the tolerances set for the first proto, 147 * we don't want to bother scanning the rest of the proto list 148 * to see if we have any other reasonable matches. 149 */ 150 151 if ( mindiff * 100 > totaltrans * FIRST_MATCH_DIFF_PERCENTAGE ) 152 { 153 /* Not a good enough match. Scan the rest of the 154 * protos. 155 */ 156 for ( i = minprot; i != NIL; i = protnext[i] ) 157 { 158 d = tbldiff( state, i, extrct[1 - extptr] ); 159 if ( d < mindiff ) 160 { 161 extptr = 1 - extptr; 162 mindiff = d; 163 minprot = i; 164 } 165 } 166 } 167 168 /* Check if the proto we've decided on as our best bet is close 169 * enough to the state we want to match to be usable. 170 */ 171 172 if ( mindiff * 100 > totaltrans * ACCEPTABLE_DIFF_PERCENTAGE ) 173 { 174 /* No good. If the state is homogeneous enough, 175 * we make a template out of it. Otherwise, we 176 * make a proto. 177 */ 178 179 if ( comfreq * 100 >= 180 totaltrans * TEMPLATE_SAME_PERCENTAGE ) 181 mktemplate( state, statenum, comstate ); 182 183 else 184 { 185 mkprot( state, statenum, comstate ); 186 mkentry( state, numecs, statenum, 187 JAMSTATE, totaltrans ); 188 } 189 } 190 191 else 192 { /* use the proto */ 193 mkentry( extrct[extptr], numecs, statenum, 194 prottbl[minprot], mindiff ); 195 196 /* If this state was sufficiently different from the 197 * proto we built it from, make it, too, a proto. 198 */ 199 200 if ( mindiff * 100 >= 201 totaltrans * NEW_PROTO_DIFF_PERCENTAGE ) 202 mkprot( state, statenum, comstate ); 203 204 /* Since mkprot added a new proto to the proto queue, 205 * it's possible that "minprot" is no longer on the 206 * proto queue (if it happened to have been the last 207 * entry, it would have been bumped off). If it's 208 * not there, then the new proto took its physical 209 * place (though logically the new proto is at the 210 * beginning of the queue), so in that case the 211 * following call will do nothing. 212 */ 213 214 mv2front( minprot ); 215 } 216 } 217 } 218 219 220 /* cmptmps - compress template table entries 221 * 222 * Template tables are compressed by using the 'template equivalence 223 * classes', which are collections of transition character equivalence 224 * classes which always appear together in templates - really meta-equivalence 225 * classes. 226 */ 227 228 void cmptmps() 229 { 230 int tmpstorage[CSIZE + 1]; 231 register int *tmp = tmpstorage, i, j; 232 int totaltrans, trans; 233 234 peakpairs = numtemps * numecs + tblend; 235 236 if ( usemecs ) 237 { 238 /* Create equivalence classes based on data gathered on 239 * template transitions. 240 */ 241 nummecs = cre8ecs( tecfwd, tecbck, numecs ); 242 } 243 244 else 245 nummecs = numecs; 246 247 while ( lastdfa + numtemps + 1 >= current_max_dfas ) 248 increase_max_dfas(); 249 250 /* Loop through each template. */ 251 252 for ( i = 1; i <= numtemps; ++i ) 253 { 254 /* Number of non-jam transitions out of this template. */ 255 totaltrans = 0; 256 257 for ( j = 1; j <= numecs; ++j ) 258 { 259 trans = tnxt[numecs * i + j]; 260 261 if ( usemecs ) 262 { 263 /* The absolute value of tecbck is the 264 * meta-equivalence class of a given 265 * equivalence class, as set up by cre8ecs(). 266 */ 267 if ( tecbck[j] > 0 ) 268 { 269 tmp[tecbck[j]] = trans; 270 271 if ( trans > 0 ) 272 ++totaltrans; 273 } 274 } 275 276 else 277 { 278 tmp[j] = trans; 279 280 if ( trans > 0 ) 281 ++totaltrans; 282 } 283 } 284 285 /* It is assumed (in a rather subtle way) in the skeleton 286 * that if we're using meta-equivalence classes, the def[] 287 * entry for all templates is the jam template, i.e., 288 * templates never default to other non-jam table entries 289 * (e.g., another template) 290 */ 291 292 /* Leave room for the jam-state after the last real state. */ 293 mkentry( tmp, nummecs, lastdfa + i + 1, JAMSTATE, totaltrans ); 294 } 295 } 296 297 298 299 /* expand_nxt_chk - expand the next check arrays */ 300 301 void expand_nxt_chk() 302 { 303 register int old_max = current_max_xpairs; 304 305 current_max_xpairs += MAX_XPAIRS_INCREMENT; 306 307 ++num_reallocs; 308 309 nxt = reallocate_integer_array( nxt, current_max_xpairs ); 310 chk = reallocate_integer_array( chk, current_max_xpairs ); 311 312 zero_out( (char *) (chk + old_max), 313 (size_t) (MAX_XPAIRS_INCREMENT * sizeof( int )) ); 314 } 315 316 317 /* find_table_space - finds a space in the table for a state to be placed 318 * 319 * synopsis 320 * int *state, numtrans, block_start; 321 * int find_table_space(); 322 * 323 * block_start = find_table_space( state, numtrans ); 324 * 325 * State is the state to be added to the full speed transition table. 326 * Numtrans is the number of out-transitions for the state. 327 * 328 * find_table_space() returns the position of the start of the first block (in 329 * chk) able to accommodate the state 330 * 331 * In determining if a state will or will not fit, find_table_space() must take 332 * into account the fact that an end-of-buffer state will be added at [0], 333 * and an action number will be added in [-1]. 334 */ 335 336 int find_table_space( state, numtrans ) 337 int *state, numtrans; 338 { 339 /* Firstfree is the position of the first possible occurrence of two 340 * consecutive unused records in the chk and nxt arrays. 341 */ 342 register int i; 343 register int *state_ptr, *chk_ptr; 344 register int *ptr_to_last_entry_in_state; 345 346 /* If there are too many out-transitions, put the state at the end of 347 * nxt and chk. 348 */ 349 if ( numtrans > MAX_XTIONS_FULL_INTERIOR_FIT ) 350 { 351 /* If table is empty, return the first available spot in 352 * chk/nxt, which should be 1. 353 */ 354 if ( tblend < 2 ) 355 return 1; 356 357 /* Start searching for table space near the end of 358 * chk/nxt arrays. 359 */ 360 i = tblend - numecs; 361 } 362 363 else 364 /* Start searching for table space from the beginning 365 * (skipping only the elements which will definitely not 366 * hold the new state). 367 */ 368 i = firstfree; 369 370 while ( 1 ) /* loops until a space is found */ 371 { 372 while ( i + numecs >= current_max_xpairs ) 373 expand_nxt_chk(); 374 375 /* Loops until space for end-of-buffer and action number 376 * are found. 377 */ 378 while ( 1 ) 379 { 380 /* Check for action number space. */ 381 if ( chk[i - 1] == 0 ) 382 { 383 /* Check for end-of-buffer space. */ 384 if ( chk[i] == 0 ) 385 break; 386 387 else 388 /* Since i != 0, there is no use 389 * checking to see if (++i) - 1 == 0, 390 * because that's the same as i == 0, 391 * so we skip a space. 392 */ 393 i += 2; 394 } 395 396 else 397 ++i; 398 399 while ( i + numecs >= current_max_xpairs ) 400 expand_nxt_chk(); 401 } 402 403 /* If we started search from the beginning, store the new 404 * firstfree for the next call of find_table_space(). 405 */ 406 if ( numtrans <= MAX_XTIONS_FULL_INTERIOR_FIT ) 407 firstfree = i + 1; 408 409 /* Check to see if all elements in chk (and therefore nxt) 410 * that are needed for the new state have not yet been taken. 411 */ 412 413 state_ptr = &state[1]; 414 ptr_to_last_entry_in_state = &chk[i + numecs + 1]; 415 416 for ( chk_ptr = &chk[i + 1]; 417 chk_ptr != ptr_to_last_entry_in_state; ++chk_ptr ) 418 if ( *(state_ptr++) != 0 && *chk_ptr != 0 ) 419 break; 420 421 if ( chk_ptr == ptr_to_last_entry_in_state ) 422 return i; 423 424 else 425 ++i; 426 } 427 } 428 429 430 /* inittbl - initialize transition tables 431 * 432 * Initializes "firstfree" to be one beyond the end of the table. Initializes 433 * all "chk" entries to be zero. 434 */ 435 void inittbl() 436 { 437 register int i; 438 439 zero_out( (char *) chk, (size_t) (current_max_xpairs * sizeof( int )) ); 440 441 tblend = 0; 442 firstfree = tblend + 1; 443 numtemps = 0; 444 445 if ( usemecs ) 446 { 447 /* Set up doubly-linked meta-equivalence classes; these 448 * are sets of equivalence classes which all have identical 449 * transitions out of TEMPLATES. 450 */ 451 452 tecbck[1] = NIL; 453 454 for ( i = 2; i <= numecs; ++i ) 455 { 456 tecbck[i] = i - 1; 457 tecfwd[i - 1] = i; 458 } 459 460 tecfwd[numecs] = NIL; 461 } 462 } 463 464 465 /* mkdeftbl - make the default, "jam" table entries */ 466 467 void mkdeftbl() 468 { 469 int i; 470 471 jamstate = lastdfa + 1; 472 473 ++tblend; /* room for transition on end-of-buffer character */ 474 475 while ( tblend + numecs >= current_max_xpairs ) 476 expand_nxt_chk(); 477 478 /* Add in default end-of-buffer transition. */ 479 nxt[tblend] = end_of_buffer_state; 480 chk[tblend] = jamstate; 481 482 for ( i = 1; i <= numecs; ++i ) 483 { 484 nxt[tblend + i] = 0; 485 chk[tblend + i] = jamstate; 486 } 487 488 jambase = tblend; 489 490 base[jamstate] = jambase; 491 def[jamstate] = 0; 492 493 tblend += numecs; 494 ++numtemps; 495 } 496 497 498 /* mkentry - create base/def and nxt/chk entries for transition array 499 * 500 * synopsis 501 * int state[numchars + 1], numchars, statenum, deflink, totaltrans; 502 * mkentry( state, numchars, statenum, deflink, totaltrans ); 503 * 504 * "state" is a transition array "numchars" characters in size, "statenum" 505 * is the offset to be used into the base/def tables, and "deflink" is the 506 * entry to put in the "def" table entry. If "deflink" is equal to 507 * "JAMSTATE", then no attempt will be made to fit zero entries of "state" 508 * (i.e., jam entries) into the table. It is assumed that by linking to 509 * "JAMSTATE" they will be taken care of. In any case, entries in "state" 510 * marking transitions to "SAME_TRANS" are treated as though they will be 511 * taken care of by whereever "deflink" points. "totaltrans" is the total 512 * number of transitions out of the state. If it is below a certain threshold, 513 * the tables are searched for an interior spot that will accommodate the 514 * state array. 515 */ 516 517 void mkentry( state, numchars, statenum, deflink, totaltrans ) 518 register int *state; 519 int numchars, statenum, deflink, totaltrans; 520 { 521 register int minec, maxec, i, baseaddr; 522 int tblbase, tbllast; 523 524 if ( totaltrans == 0 ) 525 { /* there are no out-transitions */ 526 if ( deflink == JAMSTATE ) 527 base[statenum] = JAMSTATE; 528 else 529 base[statenum] = 0; 530 531 def[statenum] = deflink; 532 return; 533 } 534 535 for ( minec = 1; minec <= numchars; ++minec ) 536 { 537 if ( state[minec] != SAME_TRANS ) 538 if ( state[minec] != 0 || deflink != JAMSTATE ) 539 break; 540 } 541 542 if ( totaltrans == 1 ) 543 { 544 /* There's only one out-transition. Save it for later to fill 545 * in holes in the tables. 546 */ 547 stack1( statenum, minec, state[minec], deflink ); 548 return; 549 } 550 551 for ( maxec = numchars; maxec > 0; --maxec ) 552 { 553 if ( state[maxec] != SAME_TRANS ) 554 if ( state[maxec] != 0 || deflink != JAMSTATE ) 555 break; 556 } 557 558 /* Whether we try to fit the state table in the middle of the table 559 * entries we have already generated, or if we just take the state 560 * table at the end of the nxt/chk tables, we must make sure that we 561 * have a valid base address (i.e., non-negative). Note that 562 * negative base addresses dangerous at run-time (because indexing 563 * the nxt array with one and a low-valued character will access 564 * memory before the start of the array. 565 */ 566 567 /* Find the first transition of state that we need to worry about. */ 568 if ( totaltrans * 100 <= numchars * INTERIOR_FIT_PERCENTAGE ) 569 { 570 /* Attempt to squeeze it into the middle of the tables. */ 571 baseaddr = firstfree; 572 573 while ( baseaddr < minec ) 574 { 575 /* Using baseaddr would result in a negative base 576 * address below; find the next free slot. 577 */ 578 for ( ++baseaddr; chk[baseaddr] != 0; ++baseaddr ) 579 ; 580 } 581 582 while ( baseaddr + maxec - minec + 1 >= current_max_xpairs ) 583 expand_nxt_chk(); 584 585 for ( i = minec; i <= maxec; ++i ) 586 if ( state[i] != SAME_TRANS && 587 (state[i] != 0 || deflink != JAMSTATE) && 588 chk[baseaddr + i - minec] != 0 ) 589 { /* baseaddr unsuitable - find another */ 590 for ( ++baseaddr; 591 baseaddr < current_max_xpairs && 592 chk[baseaddr] != 0; ++baseaddr ) 593 ; 594 595 while ( baseaddr + maxec - minec + 1 >= 596 current_max_xpairs ) 597 expand_nxt_chk(); 598 599 /* Reset the loop counter so we'll start all 600 * over again next time it's incremented. 601 */ 602 603 i = minec - 1; 604 } 605 } 606 607 else 608 { 609 /* Ensure that the base address we eventually generate is 610 * non-negative. 611 */ 612 baseaddr = MAX( tblend + 1, minec ); 613 } 614 615 tblbase = baseaddr - minec; 616 tbllast = tblbase + maxec; 617 618 while ( tbllast + 1 >= current_max_xpairs ) 619 expand_nxt_chk(); 620 621 base[statenum] = tblbase; 622 def[statenum] = deflink; 623 624 for ( i = minec; i <= maxec; ++i ) 625 if ( state[i] != SAME_TRANS ) 626 if ( state[i] != 0 || deflink != JAMSTATE ) 627 { 628 nxt[tblbase + i] = state[i]; 629 chk[tblbase + i] = statenum; 630 } 631 632 if ( baseaddr == firstfree ) 633 /* Find next free slot in tables. */ 634 for ( ++firstfree; chk[firstfree] != 0; ++firstfree ) 635 ; 636 637 tblend = MAX( tblend, tbllast ); 638 } 639 640 641 /* mk1tbl - create table entries for a state (or state fragment) which 642 * has only one out-transition 643 */ 644 645 void mk1tbl( state, sym, onenxt, onedef ) 646 int state, sym, onenxt, onedef; 647 { 648 if ( firstfree < sym ) 649 firstfree = sym; 650 651 while ( chk[firstfree] != 0 ) 652 if ( ++firstfree >= current_max_xpairs ) 653 expand_nxt_chk(); 654 655 base[state] = firstfree - sym; 656 def[state] = onedef; 657 chk[firstfree] = state; 658 nxt[firstfree] = onenxt; 659 660 if ( firstfree > tblend ) 661 { 662 tblend = firstfree++; 663 664 if ( firstfree >= current_max_xpairs ) 665 expand_nxt_chk(); 666 } 667 } 668 669 670 /* mkprot - create new proto entry */ 671 672 void mkprot( state, statenum, comstate ) 673 int state[], statenum, comstate; 674 { 675 int i, slot, tblbase; 676 677 if ( ++numprots >= MSP || numecs * numprots >= PROT_SAVE_SIZE ) 678 { 679 /* Gotta make room for the new proto by dropping last entry in 680 * the queue. 681 */ 682 slot = lastprot; 683 lastprot = protprev[lastprot]; 684 protnext[lastprot] = NIL; 685 } 686 687 else 688 slot = numprots; 689 690 protnext[slot] = firstprot; 691 692 if ( firstprot != NIL ) 693 protprev[firstprot] = slot; 694 695 firstprot = slot; 696 prottbl[slot] = statenum; 697 protcomst[slot] = comstate; 698 699 /* Copy state into save area so it can be compared with rapidly. */ 700 tblbase = numecs * (slot - 1); 701 702 for ( i = 1; i <= numecs; ++i ) 703 protsave[tblbase + i] = state[i]; 704 } 705 706 707 /* mktemplate - create a template entry based on a state, and connect the state 708 * to it 709 */ 710 711 void mktemplate( state, statenum, comstate ) 712 int state[], statenum, comstate; 713 { 714 int i, numdiff, tmpbase, tmp[CSIZE + 1]; 715 Char transset[CSIZE + 1]; 716 int tsptr; 717 718 ++numtemps; 719 720 tsptr = 0; 721 722 /* Calculate where we will temporarily store the transition table 723 * of the template in the tnxt[] array. The final transition table 724 * gets created by cmptmps(). 725 */ 726 727 tmpbase = numtemps * numecs; 728 729 if ( tmpbase + numecs >= current_max_template_xpairs ) 730 { 731 current_max_template_xpairs += MAX_TEMPLATE_XPAIRS_INCREMENT; 732 733 ++num_reallocs; 734 735 tnxt = reallocate_integer_array( tnxt, 736 current_max_template_xpairs ); 737 } 738 739 for ( i = 1; i <= numecs; ++i ) 740 if ( state[i] == 0 ) 741 tnxt[tmpbase + i] = 0; 742 else 743 { 744 transset[tsptr++] = i; 745 tnxt[tmpbase + i] = comstate; 746 } 747 748 if ( usemecs ) 749 mkeccl( transset, tsptr, tecfwd, tecbck, numecs, 0 ); 750 751 mkprot( tnxt + tmpbase, -numtemps, comstate ); 752 753 /* We rely on the fact that mkprot adds things to the beginning 754 * of the proto queue. 755 */ 756 757 numdiff = tbldiff( state, firstprot, tmp ); 758 mkentry( tmp, numecs, statenum, -numtemps, numdiff ); 759 } 760 761 762 /* mv2front - move proto queue element to front of queue */ 763 764 void mv2front( qelm ) 765 int qelm; 766 { 767 if ( firstprot != qelm ) 768 { 769 if ( qelm == lastprot ) 770 lastprot = protprev[lastprot]; 771 772 protnext[protprev[qelm]] = protnext[qelm]; 773 774 if ( protnext[qelm] != NIL ) 775 protprev[protnext[qelm]] = protprev[qelm]; 776 777 protprev[qelm] = NIL; 778 protnext[qelm] = firstprot; 779 protprev[firstprot] = qelm; 780 firstprot = qelm; 781 } 782 } 783 784 785 /* place_state - place a state into full speed transition table 786 * 787 * State is the statenum'th state. It is indexed by equivalence class and 788 * gives the number of the state to enter for a given equivalence class. 789 * Transnum is the number of out-transitions for the state. 790 */ 791 792 void place_state( state, statenum, transnum ) 793 int *state, statenum, transnum; 794 { 795 register int i; 796 register int *state_ptr; 797 int position = find_table_space( state, transnum ); 798 799 /* "base" is the table of start positions. */ 800 base[statenum] = position; 801 802 /* Put in action number marker; this non-zero number makes sure that 803 * find_table_space() knows that this position in chk/nxt is taken 804 * and should not be used for another accepting number in another 805 * state. 806 */ 807 chk[position - 1] = 1; 808 809 /* Put in end-of-buffer marker; this is for the same purposes as 810 * above. 811 */ 812 chk[position] = 1; 813 814 /* Place the state into chk and nxt. */ 815 state_ptr = &state[1]; 816 817 for ( i = 1; i <= numecs; ++i, ++state_ptr ) 818 if ( *state_ptr != 0 ) 819 { 820 chk[position + i] = i; 821 nxt[position + i] = *state_ptr; 822 } 823 824 if ( position + numecs > tblend ) 825 tblend = position + numecs; 826 } 827 828 829 /* stack1 - save states with only one out-transition to be processed later 830 * 831 * If there's room for another state on the "one-transition" stack, the 832 * state is pushed onto it, to be processed later by mk1tbl. If there's 833 * no room, we process the sucker right now. 834 */ 835 836 void stack1( statenum, sym, nextstate, deflink ) 837 int statenum, sym, nextstate, deflink; 838 { 839 if ( onesp >= ONE_STACK_SIZE - 1 ) 840 mk1tbl( statenum, sym, nextstate, deflink ); 841 842 else 843 { 844 ++onesp; 845 onestate[onesp] = statenum; 846 onesym[onesp] = sym; 847 onenext[onesp] = nextstate; 848 onedef[onesp] = deflink; 849 } 850 } 851 852 853 /* tbldiff - compute differences between two state tables 854 * 855 * "state" is the state array which is to be extracted from the pr'th 856 * proto. "pr" is both the number of the proto we are extracting from 857 * and an index into the save area where we can find the proto's complete 858 * state table. Each entry in "state" which differs from the corresponding 859 * entry of "pr" will appear in "ext". 860 * 861 * Entries which are the same in both "state" and "pr" will be marked 862 * as transitions to "SAME_TRANS" in "ext". The total number of differences 863 * between "state" and "pr" is returned as function value. Note that this 864 * number is "numecs" minus the number of "SAME_TRANS" entries in "ext". 865 */ 866 867 int tbldiff( state, pr, ext ) 868 int state[], pr, ext[]; 869 { 870 register int i, *sp = state, *ep = ext, *protp; 871 register int numdiff = 0; 872 873 protp = &protsave[numecs * (pr - 1)]; 874 875 for ( i = numecs; i > 0; --i ) 876 { 877 if ( *++protp == *++sp ) 878 *++ep = SAME_TRANS; 879 else 880 { 881 *++ep = *sp; 882 ++numdiff; 883 } 884 } 885 886 return numdiff; 887 } 888
