1 /* $NetBSD: tblcmp.c,v 1.3 2017/01/02 17:45:27 christos Exp $ */
2
3 /* tblcmp - table compression routines */
4
5 /* Copyright (c) 1990 The Regents of the University of California. */
6 /* All rights reserved. */
7
8 /* This code is derived from software contributed to Berkeley by */
9 /* Vern Paxson. */
10
11 /* The United States Government has rights in this work pursuant */
12 /* to contract no. DE-AC03-76SF00098 between the United States */
13 /* Department of Energy and the University of California. */
14
15 /* This file is part of flex. */
16
17 /* Redistribution and use in source and binary forms, with or without */
18 /* modification, are permitted provided that the following conditions */
19 /* are met: */
20
21 /* 1. Redistributions of source code must retain the above copyright */
22 /* notice, this list of conditions and the following disclaimer. */
23 /* 2. Redistributions in binary form must reproduce the above copyright */
24 /* notice, this list of conditions and the following disclaimer in the */
25 /* documentation and/or other materials provided with the distribution. */
26
27 /* Neither the name of the University nor the names of its contributors */
28 /* may be used to endorse or promote products derived from this software */
29 /* without specific prior written permission. */
30
31 /* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR */
32 /* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED */
33 /* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR */
34 /* PURPOSE. */
35 #include "flexdef.h"
36 __RCSID("$NetBSD: tblcmp.c,v 1.3 2017/01/02 17:45:27 christos Exp $");
37
38
39
40 /* declarations for functions that have forward references */
41
42 void mkentry(int *, int, int, int, int);
43 void mkprot(int[], int, int);
44 void mktemplate(int[], int, int);
45 void mv2front(int);
46 int tbldiff(int[], int, int[]);
47
48
49 /* bldtbl - build table entries for dfa state
50 *
51 * synopsis
52 * int state[numecs], statenum, totaltrans, comstate, comfreq;
53 * bldtbl( state, statenum, totaltrans, comstate, comfreq );
54 *
55 * State is the statenum'th dfa state. It is indexed by equivalence class and
56 * gives the number of the state to enter for a given equivalence class.
57 * totaltrans is the total number of transitions out of the state. Comstate
58 * is that state which is the destination of the most transitions out of State.
59 * Comfreq is how many transitions there are out of State to Comstate.
60 *
61 * A note on terminology:
62 * "protos" are transition tables which have a high probability of
63 * either being redundant (a state processed later will have an identical
64 * transition table) or nearly redundant (a state processed later will have
65 * many of the same out-transitions). A "most recently used" queue of
66 * protos is kept around with the hope that most states will find a proto
67 * which is similar enough to be usable, and therefore compacting the
68 * output tables.
69 * "templates" are a special type of proto. If a transition table is
70 * homogeneous or nearly homogeneous (all transitions go to the same
71 * destination) then the odds are good that future states will also go
72 * to the same destination state on basically the same character set.
73 * These homogeneous states are so common when dealing with large rule
74 * sets that they merit special attention. If the transition table were
75 * simply made into a proto, then (typically) each subsequent, similar
76 * state will differ from the proto for two out-transitions. One of these
77 * out-transitions will be that character on which the proto does not go
78 * to the common destination, and one will be that character on which the
79 * state does not go to the common destination. Templates, on the other
80 * hand, go to the common state on EVERY transition character, and therefore
81 * cost only one difference.
82 */
83
bldtbl(int state[],int statenum,int totaltrans,int comstate,int comfreq)84 void bldtbl (int state[], int statenum, int totaltrans, int comstate, int comfreq)
85 {
86 int extptr, extrct[2][CSIZE + 1];
87 int mindiff, minprot, i, d;
88
89 /* If extptr is 0 then the first array of extrct holds the result
90 * of the "best difference" to date, which is those transitions
91 * which occur in "state" but not in the proto which, to date,
92 * has the fewest differences between itself and "state". If
93 * extptr is 1 then the second array of extrct hold the best
94 * difference. The two arrays are toggled between so that the
95 * best difference to date can be kept around and also a difference
96 * just created by checking against a candidate "best" proto.
97 */
98
99 extptr = 0;
100
101 /* If the state has too few out-transitions, don't bother trying to
102 * compact its tables.
103 */
104
105 if ((totaltrans * 100) < (numecs * PROTO_SIZE_PERCENTAGE))
106 mkentry (state, numecs, statenum, JAMSTATE, totaltrans);
107
108 else {
109 /* "checkcom" is true if we should only check "state" against
110 * protos which have the same "comstate" value.
111 */
112 int checkcom =
113
114 comfreq * 100 > totaltrans * CHECK_COM_PERCENTAGE;
115
116 minprot = firstprot;
117 mindiff = totaltrans;
118
119 if (checkcom) {
120 /* Find first proto which has the same "comstate". */
121 for (i = firstprot; i != NIL; i = protnext[i])
122 if (protcomst[i] == comstate) {
123 minprot = i;
124 mindiff = tbldiff (state, minprot,
125 extrct[extptr]);
126 break;
127 }
128 }
129
130 else {
131 /* Since we've decided that the most common destination
132 * out of "state" does not occur with a high enough
133 * frequency, we set the "comstate" to zero, assuring
134 * that if this state is entered into the proto list,
135 * it will not be considered a template.
136 */
137 comstate = 0;
138
139 if (firstprot != NIL) {
140 minprot = firstprot;
141 mindiff = tbldiff (state, minprot,
142 extrct[extptr]);
143 }
144 }
145
146 /* We now have the first interesting proto in "minprot". If
147 * it matches within the tolerances set for the first proto,
148 * we don't want to bother scanning the rest of the proto list
149 * to see if we have any other reasonable matches.
150 */
151
152 if (mindiff * 100 >
153 totaltrans * FIRST_MATCH_DIFF_PERCENTAGE) {
154 /* Not a good enough match. Scan the rest of the
155 * protos.
156 */
157 for (i = minprot; i != NIL; i = protnext[i]) {
158 d = tbldiff (state, i, extrct[1 - extptr]);
159 if (d < mindiff) {
160 extptr = 1 - extptr;
161 mindiff = d;
162 minprot = i;
163 }
164 }
165 }
166
167 /* Check if the proto we've decided on as our best bet is close
168 * enough to the state we want to match to be usable.
169 */
170
171 if (mindiff * 100 >
172 totaltrans * ACCEPTABLE_DIFF_PERCENTAGE) {
173 /* No good. If the state is homogeneous enough,
174 * we make a template out of it. Otherwise, we
175 * make a proto.
176 */
177
178 if (comfreq * 100 >=
179 totaltrans * TEMPLATE_SAME_PERCENTAGE)
180 mktemplate (state, statenum,
181 comstate);
182
183 else {
184 mkprot (state, statenum, comstate);
185 mkentry (state, numecs, statenum,
186 JAMSTATE, totaltrans);
187 }
188 }
189
190 else { /* use the proto */
191 mkentry (extrct[extptr], numecs, statenum,
192 prottbl[minprot], mindiff);
193
194 /* If this state was sufficiently different from the
195 * proto we built it from, make it, too, a proto.
196 */
197
198 if (mindiff * 100 >=
199 totaltrans * NEW_PROTO_DIFF_PERCENTAGE)
200 mkprot (state, statenum, comstate);
201
202 /* Since mkprot added a new proto to the proto queue,
203 * it's possible that "minprot" is no longer on the
204 * proto queue (if it happened to have been the last
205 * entry, it would have been bumped off). If it's
206 * not there, then the new proto took its physical
207 * place (though logically the new proto is at the
208 * beginning of the queue), so in that case the
209 * following call will do nothing.
210 */
211
212 mv2front (minprot);
213 }
214 }
215 }
216
217
218 /* cmptmps - compress template table entries
219 *
220 * Template tables are compressed by using the 'template equivalence
221 * classes', which are collections of transition character equivalence
222 * classes which always appear together in templates - really meta-equivalence
223 * classes.
224 */
225
cmptmps(void)226 void cmptmps (void)
227 {
228 int tmpstorage[CSIZE + 1];
229 int *tmp = tmpstorage, i, j;
230 int totaltrans, trans;
231
232 peakpairs = numtemps * numecs + tblend;
233
234 if (usemecs) {
235 /* Create equivalence classes based on data gathered on
236 * template transitions.
237 */
238 nummecs = cre8ecs (tecfwd, tecbck, numecs);
239 }
240
241 else
242 nummecs = numecs;
243
244 while (lastdfa + numtemps + 1 >= current_max_dfas)
245 increase_max_dfas ();
246
247 /* Loop through each template. */
248
249 for (i = 1; i <= numtemps; ++i) {
250 /* Number of non-jam transitions out of this template. */
251 totaltrans = 0;
252
253 for (j = 1; j <= numecs; ++j) {
254 trans = tnxt[numecs * i + j];
255
256 if (usemecs) {
257 /* The absolute value of tecbck is the
258 * meta-equivalence class of a given
259 * equivalence class, as set up by cre8ecs().
260 */
261 if (tecbck[j] > 0) {
262 tmp[tecbck[j]] = trans;
263
264 if (trans > 0)
265 ++totaltrans;
266 }
267 }
268
269 else {
270 tmp[j] = trans;
271
272 if (trans > 0)
273 ++totaltrans;
274 }
275 }
276
277 /* It is assumed (in a rather subtle way) in the skeleton
278 * that if we're using meta-equivalence classes, the def[]
279 * entry for all templates is the jam template, i.e.,
280 * templates never default to other non-jam table entries
281 * (e.g., another template)
282 */
283
284 /* Leave room for the jam-state after the last real state. */
285 mkentry (tmp, nummecs, lastdfa + i + 1, JAMSTATE,
286 totaltrans);
287 }
288 }
289
290
291
292 /* expand_nxt_chk - expand the next check arrays */
293
expand_nxt_chk(void)294 void expand_nxt_chk (void)
295 {
296 int old_max = current_max_xpairs;
297
298 current_max_xpairs += MAX_XPAIRS_INCREMENT;
299
300 ++num_reallocs;
301
302 nxt = reallocate_integer_array (nxt, current_max_xpairs);
303 chk = reallocate_integer_array (chk, current_max_xpairs);
304
305 memset(chk + old_max, 0, MAX_XPAIRS_INCREMENT * sizeof(int));
306 }
307
308
309 /* find_table_space - finds a space in the table for a state to be placed
310 *
311 * synopsis
312 * int *state, numtrans, block_start;
313 * int find_table_space();
314 *
315 * block_start = find_table_space( state, numtrans );
316 *
317 * State is the state to be added to the full speed transition table.
318 * Numtrans is the number of out-transitions for the state.
319 *
320 * find_table_space() returns the position of the start of the first block (in
321 * chk) able to accommodate the state
322 *
323 * In determining if a state will or will not fit, find_table_space() must take
324 * into account the fact that an end-of-buffer state will be added at [0],
325 * and an action number will be added in [-1].
326 */
327
find_table_space(int * state,int numtrans)328 int find_table_space (int *state, int numtrans)
329 {
330 /* Firstfree is the position of the first possible occurrence of two
331 * consecutive unused records in the chk and nxt arrays.
332 */
333 int i;
334 int *state_ptr, *chk_ptr;
335 int *ptr_to_last_entry_in_state;
336
337 /* If there are too many out-transitions, put the state at the end of
338 * nxt and chk.
339 */
340 if (numtrans > MAX_XTIONS_FULL_INTERIOR_FIT) {
341 /* If table is empty, return the first available spot in
342 * chk/nxt, which should be 1.
343 */
344 if (tblend < 2)
345 return 1;
346
347 /* Start searching for table space near the end of
348 * chk/nxt arrays.
349 */
350 i = tblend - numecs;
351 }
352
353 else
354 /* Start searching for table space from the beginning
355 * (skipping only the elements which will definitely not
356 * hold the new state).
357 */
358 i = firstfree;
359
360 while (1) { /* loops until a space is found */
361 while (i + numecs >= current_max_xpairs)
362 expand_nxt_chk ();
363
364 /* Loops until space for end-of-buffer and action number
365 * are found.
366 */
367 while (1) {
368 /* Check for action number space. */
369 if (chk[i - 1] == 0) {
370 /* Check for end-of-buffer space. */
371 if (chk[i] == 0)
372 break;
373
374 else
375 /* Since i != 0, there is no use
376 * checking to see if (++i) - 1 == 0,
377 * because that's the same as i == 0,
378 * so we skip a space.
379 */
380 i += 2;
381 }
382
383 else
384 ++i;
385
386 while (i + numecs >= current_max_xpairs)
387 expand_nxt_chk ();
388 }
389
390 /* If we started search from the beginning, store the new
391 * firstfree for the next call of find_table_space().
392 */
393 if (numtrans <= MAX_XTIONS_FULL_INTERIOR_FIT)
394 firstfree = i + 1;
395
396 /* Check to see if all elements in chk (and therefore nxt)
397 * that are needed for the new state have not yet been taken.
398 */
399
400 state_ptr = &state[1];
401 ptr_to_last_entry_in_state = &chk[i + numecs + 1];
402
403 for (chk_ptr = &chk[i + 1];
404 chk_ptr != ptr_to_last_entry_in_state; ++chk_ptr)
405 if (*(state_ptr++) != 0 && *chk_ptr != 0)
406 break;
407
408 if (chk_ptr == ptr_to_last_entry_in_state)
409 return i;
410
411 else
412 ++i;
413 }
414 }
415
416
417 /* inittbl - initialize transition tables
418 *
419 * Initializes "firstfree" to be one beyond the end of the table. Initializes
420 * all "chk" entries to be zero.
421 */
inittbl(void)422 void inittbl (void)
423 {
424 int i;
425
426 memset(chk, 0, (size_t) current_max_xpairs * sizeof(int));
427
428 tblend = 0;
429 firstfree = tblend + 1;
430 numtemps = 0;
431
432 if (usemecs) {
433 /* Set up doubly-linked meta-equivalence classes; these
434 * are sets of equivalence classes which all have identical
435 * transitions out of TEMPLATES.
436 */
437
438 tecbck[1] = NIL;
439
440 for (i = 2; i <= numecs; ++i) {
441 tecbck[i] = i - 1;
442 tecfwd[i - 1] = i;
443 }
444
445 tecfwd[numecs] = NIL;
446 }
447 }
448
449
450 /* mkdeftbl - make the default, "jam" table entries */
451
mkdeftbl(void)452 void mkdeftbl (void)
453 {
454 int i;
455
456 jamstate = lastdfa + 1;
457
458 ++tblend; /* room for transition on end-of-buffer character */
459
460 while (tblend + numecs >= current_max_xpairs)
461 expand_nxt_chk ();
462
463 /* Add in default end-of-buffer transition. */
464 nxt[tblend] = end_of_buffer_state;
465 chk[tblend] = jamstate;
466
467 for (i = 1; i <= numecs; ++i) {
468 nxt[tblend + i] = 0;
469 chk[tblend + i] = jamstate;
470 }
471
472 jambase = tblend;
473
474 base[jamstate] = jambase;
475 def[jamstate] = 0;
476
477 tblend += numecs;
478 ++numtemps;
479 }
480
481
482 /* mkentry - create base/def and nxt/chk entries for transition array
483 *
484 * synopsis
485 * int state[numchars + 1], numchars, statenum, deflink, totaltrans;
486 * mkentry( state, numchars, statenum, deflink, totaltrans );
487 *
488 * "state" is a transition array "numchars" characters in size, "statenum"
489 * is the offset to be used into the base/def tables, and "deflink" is the
490 * entry to put in the "def" table entry. If "deflink" is equal to
491 * "JAMSTATE", then no attempt will be made to fit zero entries of "state"
492 * (i.e., jam entries) into the table. It is assumed that by linking to
493 * "JAMSTATE" they will be taken care of. In any case, entries in "state"
494 * marking transitions to "SAME_TRANS" are treated as though they will be
495 * taken care of by whereever "deflink" points. "totaltrans" is the total
496 * number of transitions out of the state. If it is below a certain threshold,
497 * the tables are searched for an interior spot that will accommodate the
498 * state array.
499 */
500
mkentry(int * state,int numchars,int statenum,int deflink,int totaltrans)501 void mkentry (int *state, int numchars, int statenum, int deflink,
502 int totaltrans)
503 {
504 int minec, maxec, i, baseaddr;
505 int tblbase, tbllast;
506
507 if (totaltrans == 0) { /* there are no out-transitions */
508 if (deflink == JAMSTATE)
509 base[statenum] = JAMSTATE;
510 else
511 base[statenum] = 0;
512
513 def[statenum] = deflink;
514 return;
515 }
516
517 for (minec = 1; minec <= numchars; ++minec) {
518 if (state[minec] != SAME_TRANS)
519 if (state[minec] != 0 || deflink != JAMSTATE)
520 break;
521 }
522
523 if (totaltrans == 1) {
524 /* There's only one out-transition. Save it for later to fill
525 * in holes in the tables.
526 */
527 stack1 (statenum, minec, state[minec], deflink);
528 return;
529 }
530
531 for (maxec = numchars; maxec > 0; --maxec) {
532 if (state[maxec] != SAME_TRANS)
533 if (state[maxec] != 0 || deflink != JAMSTATE)
534 break;
535 }
536
537 /* Whether we try to fit the state table in the middle of the table
538 * entries we have already generated, or if we just take the state
539 * table at the end of the nxt/chk tables, we must make sure that we
540 * have a valid base address (i.e., non-negative). Note that
541 * negative base addresses dangerous at run-time (because indexing
542 * the nxt array with one and a low-valued character will access
543 * memory before the start of the array.
544 */
545
546 /* Find the first transition of state that we need to worry about. */
547 if (totaltrans * 100 <= numchars * INTERIOR_FIT_PERCENTAGE) {
548 /* Attempt to squeeze it into the middle of the tables. */
549 baseaddr = firstfree;
550
551 while (baseaddr < minec) {
552 /* Using baseaddr would result in a negative base
553 * address below; find the next free slot.
554 */
555 for (++baseaddr; chk[baseaddr] != 0; ++baseaddr) ;
556 }
557
558 while (baseaddr + maxec - minec + 1 >= current_max_xpairs)
559 expand_nxt_chk ();
560
561 for (i = minec; i <= maxec; ++i)
562 if (state[i] != SAME_TRANS &&
563 (state[i] != 0 || deflink != JAMSTATE) &&
564 chk[baseaddr + i - minec] != 0) { /* baseaddr unsuitable - find another */
565 for (++baseaddr;
566 baseaddr < current_max_xpairs &&
567 chk[baseaddr] != 0; ++baseaddr) ;
568
569 while (baseaddr + maxec - minec + 1 >=
570 current_max_xpairs)
571 expand_nxt_chk ();
572
573 /* Reset the loop counter so we'll start all
574 * over again next time it's incremented.
575 */
576
577 i = minec - 1;
578 }
579 }
580
581 else {
582 /* Ensure that the base address we eventually generate is
583 * non-negative.
584 */
585 baseaddr = MAX (tblend + 1, minec);
586 }
587
588 tblbase = baseaddr - minec;
589 tbllast = tblbase + maxec;
590
591 while (tbllast + 1 >= current_max_xpairs)
592 expand_nxt_chk ();
593
594 base[statenum] = tblbase;
595 def[statenum] = deflink;
596
597 for (i = minec; i <= maxec; ++i)
598 if (state[i] != SAME_TRANS)
599 if (state[i] != 0 || deflink != JAMSTATE) {
600 nxt[tblbase + i] = state[i];
601 chk[tblbase + i] = statenum;
602 }
603
604 if (baseaddr == firstfree)
605 /* Find next free slot in tables. */
606 for (++firstfree; chk[firstfree] != 0; ++firstfree) ;
607
608 tblend = MAX (tblend, tbllast);
609 }
610
611
612 /* mk1tbl - create table entries for a state (or state fragment) which
613 * has only one out-transition
614 */
615
mk1tbl(int state,int sym,int onenxt,int onedef)616 void mk1tbl (int state, int sym, int onenxt, int onedef)
617 {
618 if (firstfree < sym)
619 firstfree = sym;
620
621 while (chk[firstfree] != 0)
622 if (++firstfree >= current_max_xpairs)
623 expand_nxt_chk ();
624
625 base[state] = firstfree - sym;
626 def[state] = onedef;
627 chk[firstfree] = state;
628 nxt[firstfree] = onenxt;
629
630 if (firstfree > tblend) {
631 tblend = firstfree++;
632
633 if (firstfree >= current_max_xpairs)
634 expand_nxt_chk ();
635 }
636 }
637
638
639 /* mkprot - create new proto entry */
640
mkprot(int state[],int statenum,int comstate)641 void mkprot (int state[], int statenum, int comstate)
642 {
643 int i, slot, tblbase;
644
645 if (++numprots >= MSP || numecs * numprots >= PROT_SAVE_SIZE) {
646 /* Gotta make room for the new proto by dropping last entry in
647 * the queue.
648 */
649 slot = lastprot;
650 lastprot = protprev[lastprot];
651 protnext[lastprot] = NIL;
652 }
653
654 else
655 slot = numprots;
656
657 protnext[slot] = firstprot;
658
659 if (firstprot != NIL)
660 protprev[firstprot] = slot;
661
662 firstprot = slot;
663 prottbl[slot] = statenum;
664 protcomst[slot] = comstate;
665
666 /* Copy state into save area so it can be compared with rapidly. */
667 tblbase = numecs * (slot - 1);
668
669 for (i = 1; i <= numecs; ++i)
670 protsave[tblbase + i] = state[i];
671 }
672
673
674 /* mktemplate - create a template entry based on a state, and connect the state
675 * to it
676 */
677
mktemplate(int state[],int statenum,int comstate)678 void mktemplate (int state[], int statenum, int comstate)
679 {
680 int i, numdiff, tmpbase, tmp[CSIZE + 1];
681 unsigned char transset[CSIZE + 1];
682 int tsptr;
683
684 ++numtemps;
685
686 tsptr = 0;
687
688 /* Calculate where we will temporarily store the transition table
689 * of the template in the tnxt[] array. The final transition table
690 * gets created by cmptmps().
691 */
692
693 tmpbase = numtemps * numecs;
694
695 if (tmpbase + numecs >= current_max_template_xpairs) {
696 current_max_template_xpairs +=
697 MAX_TEMPLATE_XPAIRS_INCREMENT;
698
699 ++num_reallocs;
700
701 tnxt = reallocate_integer_array (tnxt,
702 current_max_template_xpairs);
703 }
704
705 for (i = 1; i <= numecs; ++i)
706 if (state[i] == 0)
707 tnxt[tmpbase + i] = 0;
708 else {
709 /* Note: range 1..256 is mapped to 1..255,0 */
710 transset[tsptr++] = (unsigned char) i;
711 tnxt[tmpbase + i] = comstate;
712 }
713
714 if (usemecs)
715 mkeccl (transset, tsptr, tecfwd, tecbck, numecs, 0);
716
717 mkprot (tnxt + tmpbase, -numtemps, comstate);
718
719 /* We rely on the fact that mkprot adds things to the beginning
720 * of the proto queue.
721 */
722
723 numdiff = tbldiff (state, firstprot, tmp);
724 mkentry (tmp, numecs, statenum, -numtemps, numdiff);
725 }
726
727
728 /* mv2front - move proto queue element to front of queue */
729
mv2front(int qelm)730 void mv2front (int qelm)
731 {
732 if (firstprot != qelm) {
733 if (qelm == lastprot)
734 lastprot = protprev[lastprot];
735
736 protnext[protprev[qelm]] = protnext[qelm];
737
738 if (protnext[qelm] != NIL)
739 protprev[protnext[qelm]] = protprev[qelm];
740
741 protprev[qelm] = NIL;
742 protnext[qelm] = firstprot;
743 protprev[firstprot] = qelm;
744 firstprot = qelm;
745 }
746 }
747
748
749 /* place_state - place a state into full speed transition table
750 *
751 * State is the statenum'th state. It is indexed by equivalence class and
752 * gives the number of the state to enter for a given equivalence class.
753 * Transnum is the number of out-transitions for the state.
754 */
755
place_state(int * state,int statenum,int transnum)756 void place_state (int *state, int statenum, int transnum)
757 {
758 int i;
759 int *state_ptr;
760 int position = find_table_space (state, transnum);
761
762 /* "base" is the table of start positions. */
763 base[statenum] = position;
764
765 /* Put in action number marker; this non-zero number makes sure that
766 * find_table_space() knows that this position in chk/nxt is taken
767 * and should not be used for another accepting number in another
768 * state.
769 */
770 chk[position - 1] = 1;
771
772 /* Put in end-of-buffer marker; this is for the same purposes as
773 * above.
774 */
775 chk[position] = 1;
776
777 /* Place the state into chk and nxt. */
778 state_ptr = &state[1];
779
780 for (i = 1; i <= numecs; ++i, ++state_ptr)
781 if (*state_ptr != 0) {
782 chk[position + i] = i;
783 nxt[position + i] = *state_ptr;
784 }
785
786 if (position + numecs > tblend)
787 tblend = position + numecs;
788 }
789
790
791 /* stack1 - save states with only one out-transition to be processed later
792 *
793 * If there's room for another state on the "one-transition" stack, the
794 * state is pushed onto it, to be processed later by mk1tbl. If there's
795 * no room, we process the sucker right now.
796 */
797
stack1(int statenum,int sym,int nextstate,int deflink)798 void stack1 (int statenum, int sym, int nextstate, int deflink)
799 {
800 if (onesp >= ONE_STACK_SIZE - 1)
801 mk1tbl (statenum, sym, nextstate, deflink);
802
803 else {
804 ++onesp;
805 onestate[onesp] = statenum;
806 onesym[onesp] = sym;
807 onenext[onesp] = nextstate;
808 onedef[onesp] = deflink;
809 }
810 }
811
812
813 /* tbldiff - compute differences between two state tables
814 *
815 * "state" is the state array which is to be extracted from the pr'th
816 * proto. "pr" is both the number of the proto we are extracting from
817 * and an index into the save area where we can find the proto's complete
818 * state table. Each entry in "state" which differs from the corresponding
819 * entry of "pr" will appear in "ext".
820 *
821 * Entries which are the same in both "state" and "pr" will be marked
822 * as transitions to "SAME_TRANS" in "ext". The total number of differences
823 * between "state" and "pr" is returned as function value. Note that this
824 * number is "numecs" minus the number of "SAME_TRANS" entries in "ext".
825 */
826
tbldiff(int state[],int pr,int ext[])827 int tbldiff (int state[], int pr, int ext[])
828 {
829 int i, *sp = state, *ep = ext, *protp;
830 int numdiff = 0;
831
832 protp = &protsave[numecs * (pr - 1)];
833
834 for (i = numecs; i > 0; --i) {
835 if (*++protp == *++sp)
836 *++ep = SAME_TRANS;
837 else {
838 *++ep = *sp;
839 ++numdiff;
840 }
841 }
842
843 return numdiff;
844 }
845