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