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