1 /* tblcmp - table compression routines */
4 * Copyright (c) 1990 The Regents of the University of California.
7 * This code is derived from software contributed to Berkeley by
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.
14 * Redistribution and use in source and binary forms are permitted provided
15 * that: (1) source distributions retain this entire copyright notice and
16 * comment, and (2) distributions including binaries display the following
17 * acknowledgement: ``This product includes software developed by the
18 * University of California, Berkeley and its contributors'' in the
19 * documentation or other materials provided with the distribution and in
20 * all advertising materials mentioning features or use of this software.
21 * Neither the name of the University nor the names of its contributors may
22 * be used to endorse or promote products derived from this software without
23 * 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.
29 /* $Header: /home/daffy/u0/vern/flex/RCS/tblcmp.c,v 2.11 94/11/05 17:08:28 vern Exp $ */
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
36 /* declarations for functions that have forward references */
38 void mkentry PROTO((int*, int, int, int, int));
39 void mkprot PROTO((int[], int, int));
40 void mktemplate PROTO((int[], int, int));
41 void mv2front PROTO((int));
42 int tbldiff PROTO((int[], int, int[]));
45 /* bldtbl - build table entries for dfa state
48 * int state[numecs], statenum, totaltrans, comstate, comfreq;
49 * bldtbl( state, statenum, totaltrans, comstate, comfreq );
51 * State is the statenum'th dfa state. It is indexed by equivalence class and
52 * gives the number of the state to enter for a given equivalence class.
53 * totaltrans is the total number of transitions out of the state. Comstate
54 * is that state which is the destination of the most transitions out of State.
55 * Comfreq is how many transitions there are out of State to Comstate.
57 * A note on terminology:
58 * "protos" are transition tables which have a high probability of
59 * either being redundant (a state processed later will have an identical
60 * transition table) or nearly redundant (a state processed later will have
61 * many of the same out-transitions). A "most recently used" queue of
62 * protos is kept around with the hope that most states will find a proto
63 * which is similar enough to be usable, and therefore compacting the
65 * "templates" are a special type of proto. If a transition table is
66 * homogeneous or nearly homogeneous (all transitions go to the same
67 * destination) then the odds are good that future states will also go
68 * to the same destination state on basically the same character set.
69 * These homogeneous states are so common when dealing with large rule
70 * sets that they merit special attention. If the transition table were
71 * simply made into a proto, then (typically) each subsequent, similar
72 * state will differ from the proto for two out-transitions. One of these
73 * out-transitions will be that character on which the proto does not go
74 * to the common destination, and one will be that character on which the
75 * state does not go to the common destination. Templates, on the other
76 * hand, go to the common state on EVERY transition character, and therefore
77 * cost only one difference.
80 void bldtbl( state, statenum, totaltrans, comstate, comfreq )
81 int state[], statenum, totaltrans, comstate, comfreq;
83 int extptr, extrct[2][CSIZE + 1];
84 int mindiff, minprot, i, d;
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.
98 /* If the state has too few out-transitions, don't bother trying to
102 if ( (totaltrans * 100) < (numecs * PROTO_SIZE_PERCENTAGE) )
103 mkentry( state, numecs, statenum, JAMSTATE, totaltrans );
107 /* "checkcom" is true if we should only check "state" against
108 * protos which have the same "comstate" value.
111 comfreq * 100 > totaltrans * CHECK_COM_PERCENTAGE;
114 mindiff = totaltrans;
118 /* Find first proto which has the same "comstate". */
119 for ( i = firstprot; i != NIL; i = protnext[i] )
120 if ( protcomst[i] == comstate )
123 mindiff = tbldiff( state, minprot,
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.
139 if ( firstprot != NIL )
142 mindiff = tbldiff( state, minprot,
147 /* We now have the first interesting proto in "minprot". If
148 * it matches within the tolerances set for the first proto,
149 * we don't want to bother scanning the rest of the proto list
150 * to see if we have any other reasonable matches.
153 if ( mindiff * 100 > totaltrans * FIRST_MATCH_DIFF_PERCENTAGE )
155 /* Not a good enough match. Scan the rest of the
158 for ( i = minprot; i != NIL; i = protnext[i] )
160 d = tbldiff( state, i, extrct[1 - extptr] );
170 /* Check if the proto we've decided on as our best bet is close
171 * enough to the state we want to match to be usable.
174 if ( mindiff * 100 > totaltrans * ACCEPTABLE_DIFF_PERCENTAGE )
176 /* No good. If the state is homogeneous enough,
177 * we make a template out of it. Otherwise, we
181 if ( comfreq * 100 >=
182 totaltrans * TEMPLATE_SAME_PERCENTAGE )
183 mktemplate( state, statenum, comstate );
187 mkprot( state, statenum, comstate );
188 mkentry( state, numecs, statenum,
189 JAMSTATE, totaltrans );
194 { /* use the proto */
195 mkentry( extrct[extptr], numecs, statenum,
196 prottbl[minprot], mindiff );
198 /* If this state was sufficiently different from the
199 * proto we built it from, make it, too, a proto.
202 if ( mindiff * 100 >=
203 totaltrans * NEW_PROTO_DIFF_PERCENTAGE )
204 mkprot( state, statenum, comstate );
206 /* Since mkprot added a new proto to the proto queue,
207 * it's possible that "minprot" is no longer on the
208 * proto queue (if it happened to have been the last
209 * entry, it would have been bumped off). If it's
210 * not there, then the new proto took its physical
211 * place (though logically the new proto is at the
212 * beginning of the queue), so in that case the
213 * following call will do nothing.
222 /* cmptmps - compress template table entries
224 * Template tables are compressed by using the 'template equivalence
225 * classes', which are collections of transition character equivalence
226 * classes which always appear together in templates - really meta-equivalence
232 int tmpstorage[CSIZE + 1];
233 int *tmp = tmpstorage, i, j;
234 int totaltrans, trans;
236 peakpairs = numtemps * numecs + tblend;
240 /* Create equivalence classes based on data gathered on
241 * template transitions.
243 nummecs = cre8ecs( tecfwd, tecbck, numecs );
249 while ( lastdfa + numtemps + 1 >= current_max_dfas )
252 /* Loop through each template. */
254 for ( i = 1; i <= numtemps; ++i )
256 /* Number of non-jam transitions out of this template. */
259 for ( j = 1; j <= numecs; ++j )
261 trans = tnxt[numecs * i + j];
265 /* The absolute value of tecbck is the
266 * meta-equivalence class of a given
267 * equivalence class, as set up by cre8ecs().
271 tmp[tecbck[j]] = trans;
287 /* It is assumed (in a rather subtle way) in the skeleton
288 * that if we're using meta-equivalence classes, the def[]
289 * entry for all templates is the jam template, i.e.,
290 * templates never default to other non-jam table entries
291 * (e.g., another template)
294 /* Leave room for the jam-state after the last real state. */
295 mkentry( tmp, nummecs, lastdfa + i + 1, JAMSTATE, totaltrans );
301 /* expand_nxt_chk - expand the next check arrays */
303 void expand_nxt_chk()
305 int old_max = current_max_xpairs;
307 current_max_xpairs += MAX_XPAIRS_INCREMENT;
311 nxt = reallocate_integer_array( nxt, current_max_xpairs );
312 chk = reallocate_integer_array( chk, current_max_xpairs );
314 zero_out( (char *) (chk + old_max),
315 (size_t) (MAX_XPAIRS_INCREMENT * sizeof( int )) );
319 /* find_table_space - finds a space in the table for a state to be placed
322 * int *state, numtrans, block_start;
323 * int find_table_space();
325 * block_start = find_table_space( state, numtrans );
327 * State is the state to be added to the full speed transition table.
328 * Numtrans is the number of out-transitions for the state.
330 * find_table_space() returns the position of the start of the first block (in
331 * chk) able to accommodate the state
333 * In determining if a state will or will not fit, find_table_space() must take
334 * into account the fact that an end-of-buffer state will be added at [0],
335 * and an action number will be added in [-1].
338 int find_table_space( state, numtrans )
339 int *state, numtrans;
341 /* Firstfree is the position of the first possible occurrence of two
342 * consecutive unused records in the chk and nxt arrays.
345 int *state_ptr, *chk_ptr;
346 int *ptr_to_last_entry_in_state;
348 /* If there are too many out-transitions, put the state at the end of
351 if ( numtrans > MAX_XTIONS_FULL_INTERIOR_FIT )
353 /* If table is empty, return the first available spot in
354 * chk/nxt, which should be 1.
359 /* Start searching for table space near the end of
366 /* Start searching for table space from the beginning
367 * (skipping only the elements which will definitely not
368 * hold the new state).
372 while ( 1 ) /* loops until a space is found */
374 while ( i + numecs >= current_max_xpairs )
377 /* Loops until space for end-of-buffer and action number
382 /* Check for action number space. */
383 if ( chk[i - 1] == 0 )
385 /* Check for end-of-buffer space. */
390 /* Since i != 0, there is no use
391 * checking to see if (++i) - 1 == 0,
392 * because that's the same as i == 0,
393 * so we skip a space.
401 while ( i + numecs >= current_max_xpairs )
405 /* If we started search from the beginning, store the new
406 * firstfree for the next call of find_table_space().
408 if ( numtrans <= MAX_XTIONS_FULL_INTERIOR_FIT )
411 /* Check to see if all elements in chk (and therefore nxt)
412 * that are needed for the new state have not yet been taken.
415 state_ptr = &state[1];
416 ptr_to_last_entry_in_state = &chk[i + numecs + 1];
418 for ( chk_ptr = &chk[i + 1];
419 chk_ptr != ptr_to_last_entry_in_state; ++chk_ptr )
420 if ( *(state_ptr++) != 0 && *chk_ptr != 0 )
423 if ( chk_ptr == ptr_to_last_entry_in_state )
432 /* inittbl - initialize transition tables
434 * Initializes "firstfree" to be one beyond the end of the table. Initializes
435 * all "chk" entries to be zero.
441 zero_out( (char *) chk, (size_t) (current_max_xpairs * sizeof( int )) );
444 firstfree = tblend + 1;
449 /* Set up doubly-linked meta-equivalence classes; these
450 * are sets of equivalence classes which all have identical
451 * transitions out of TEMPLATES.
456 for ( i = 2; i <= numecs; ++i )
462 tecfwd[numecs] = NIL;
467 /* mkdeftbl - make the default, "jam" table entries */
473 jamstate = lastdfa + 1;
475 ++tblend; /* room for transition on end-of-buffer character */
477 while ( tblend + numecs >= current_max_xpairs )
480 /* Add in default end-of-buffer transition. */
481 nxt[tblend] = end_of_buffer_state;
482 chk[tblend] = jamstate;
484 for ( i = 1; i <= numecs; ++i )
487 chk[tblend + i] = jamstate;
492 base[jamstate] = jambase;
500 /* mkentry - create base/def and nxt/chk entries for transition array
503 * int state[numchars + 1], numchars, statenum, deflink, totaltrans;
504 * mkentry( state, numchars, statenum, deflink, totaltrans );
506 * "state" is a transition array "numchars" characters in size, "statenum"
507 * is the offset to be used into the base/def tables, and "deflink" is the
508 * entry to put in the "def" table entry. If "deflink" is equal to
509 * "JAMSTATE", then no attempt will be made to fit zero entries of "state"
510 * (i.e., jam entries) into the table. It is assumed that by linking to
511 * "JAMSTATE" they will be taken care of. In any case, entries in "state"
512 * marking transitions to "SAME_TRANS" are treated as though they will be
513 * taken care of by whereever "deflink" points. "totaltrans" is the total
514 * number of transitions out of the state. If it is below a certain threshold,
515 * the tables are searched for an interior spot that will accommodate the
519 void mkentry( state, numchars, statenum, deflink, totaltrans )
521 int numchars, statenum, deflink, totaltrans;
523 int minec, maxec, i, baseaddr;
524 int tblbase, tbllast;
526 if ( totaltrans == 0 )
527 { /* there are no out-transitions */
528 if ( deflink == JAMSTATE )
529 base[statenum] = JAMSTATE;
533 def[statenum] = deflink;
537 for ( minec = 1; minec <= numchars; ++minec )
539 if ( state[minec] != SAME_TRANS )
540 if ( state[minec] != 0 || deflink != JAMSTATE )
544 if ( totaltrans == 1 )
546 /* There's only one out-transition. Save it for later to fill
547 * in holes in the tables.
549 stack1( statenum, minec, state[minec], deflink );
553 for ( maxec = numchars; maxec > 0; --maxec )
555 if ( state[maxec] != SAME_TRANS )
556 if ( state[maxec] != 0 || deflink != JAMSTATE )
560 /* Whether we try to fit the state table in the middle of the table
561 * entries we have already generated, or if we just take the state
562 * table at the end of the nxt/chk tables, we must make sure that we
563 * have a valid base address (i.e., non-negative). Note that
564 * negative base addresses dangerous at run-time (because indexing
565 * the nxt array with one and a low-valued character will access
566 * memory before the start of the array.
569 /* Find the first transition of state that we need to worry about. */
570 if ( totaltrans * 100 <= numchars * INTERIOR_FIT_PERCENTAGE )
572 /* Attempt to squeeze it into the middle of the tables. */
573 baseaddr = firstfree;
575 while ( baseaddr < minec )
577 /* Using baseaddr would result in a negative base
578 * address below; find the next free slot.
580 for ( ++baseaddr; chk[baseaddr] != 0; ++baseaddr )
584 while ( baseaddr + maxec - minec + 1 >= current_max_xpairs )
587 for ( i = minec; i <= maxec; ++i )
588 if ( state[i] != SAME_TRANS &&
589 (state[i] != 0 || deflink != JAMSTATE) &&
590 chk[baseaddr + i - minec] != 0 )
591 { /* baseaddr unsuitable - find another */
593 baseaddr < current_max_xpairs &&
594 chk[baseaddr] != 0; ++baseaddr )
597 while ( baseaddr + maxec - minec + 1 >=
601 /* Reset the loop counter so we'll start all
602 * over again next time it's incremented.
611 /* Ensure that the base address we eventually generate is
614 baseaddr = MAX( tblend + 1, minec );
617 tblbase = baseaddr - minec;
618 tbllast = tblbase + maxec;
620 while ( tbllast + 1 >= current_max_xpairs )
623 base[statenum] = tblbase;
624 def[statenum] = deflink;
626 for ( i = minec; i <= maxec; ++i )
627 if ( state[i] != SAME_TRANS )
628 if ( state[i] != 0 || deflink != JAMSTATE )
630 nxt[tblbase + i] = state[i];
631 chk[tblbase + i] = statenum;
634 if ( baseaddr == firstfree )
635 /* Find next free slot in tables. */
636 for ( ++firstfree; chk[firstfree] != 0; ++firstfree )
639 tblend = MAX( tblend, tbllast );
643 /* mk1tbl - create table entries for a state (or state fragment) which
644 * has only one out-transition
647 void mk1tbl( state, sym, onenxt, onedef )
648 int state, sym, onenxt, onedef;
650 if ( firstfree < sym )
653 while ( chk[firstfree] != 0 )
654 if ( ++firstfree >= current_max_xpairs )
657 base[state] = firstfree - sym;
659 chk[firstfree] = state;
660 nxt[firstfree] = onenxt;
662 if ( firstfree > tblend )
664 tblend = firstfree++;
666 if ( firstfree >= current_max_xpairs )
672 /* mkprot - create new proto entry */
674 void mkprot( state, statenum, comstate )
675 int state[], statenum, comstate;
677 int i, slot, tblbase;
679 if ( ++numprots >= MSP || numecs * numprots >= PROT_SAVE_SIZE )
681 /* Gotta make room for the new proto by dropping last entry in
685 lastprot = protprev[lastprot];
686 protnext[lastprot] = NIL;
692 protnext[slot] = firstprot;
694 if ( firstprot != NIL )
695 protprev[firstprot] = slot;
698 prottbl[slot] = statenum;
699 protcomst[slot] = comstate;
701 /* Copy state into save area so it can be compared with rapidly. */
702 tblbase = numecs * (slot - 1);
704 for ( i = 1; i <= numecs; ++i )
705 protsave[tblbase + i] = state[i];
709 /* mktemplate - create a template entry based on a state, and connect the state
713 void mktemplate( state, statenum, comstate )
714 int state[], statenum, comstate;
716 int i, numdiff, tmpbase, tmp[CSIZE + 1];
717 Char transset[CSIZE + 1];
724 /* Calculate where we will temporarily store the transition table
725 * of the template in the tnxt[] array. The final transition table
726 * gets created by cmptmps().
729 tmpbase = numtemps * numecs;
731 if ( tmpbase + numecs >= current_max_template_xpairs )
733 current_max_template_xpairs += MAX_TEMPLATE_XPAIRS_INCREMENT;
737 tnxt = reallocate_integer_array( tnxt,
738 current_max_template_xpairs );
741 for ( i = 1; i <= numecs; ++i )
743 tnxt[tmpbase + i] = 0;
746 transset[tsptr++] = i;
747 tnxt[tmpbase + i] = comstate;
751 mkeccl( transset, tsptr, tecfwd, tecbck, numecs, 0 );
753 mkprot( tnxt + tmpbase, -numtemps, comstate );
755 /* We rely on the fact that mkprot adds things to the beginning
756 * of the proto queue.
759 numdiff = tbldiff( state, firstprot, tmp );
760 mkentry( tmp, numecs, statenum, -numtemps, numdiff );
764 /* mv2front - move proto queue element to front of queue */
766 void mv2front( qelm )
769 if ( firstprot != qelm )
771 if ( qelm == lastprot )
772 lastprot = protprev[lastprot];
774 protnext[protprev[qelm]] = protnext[qelm];
776 if ( protnext[qelm] != NIL )
777 protprev[protnext[qelm]] = protprev[qelm];
779 protprev[qelm] = NIL;
780 protnext[qelm] = firstprot;
781 protprev[firstprot] = qelm;
787 /* place_state - place a state into full speed transition table
789 * State is the statenum'th state. It is indexed by equivalence class and
790 * gives the number of the state to enter for a given equivalence class.
791 * Transnum is the number of out-transitions for the state.
794 void place_state( state, statenum, transnum )
795 int *state, statenum, transnum;
799 int position = find_table_space( state, transnum );
801 /* "base" is the table of start positions. */
802 base[statenum] = position;
804 /* Put in action number marker; this non-zero number makes sure that
805 * find_table_space() knows that this position in chk/nxt is taken
806 * and should not be used for another accepting number in another
809 chk[position - 1] = 1;
811 /* Put in end-of-buffer marker; this is for the same purposes as
816 /* Place the state into chk and nxt. */
817 state_ptr = &state[1];
819 for ( i = 1; i <= numecs; ++i, ++state_ptr )
820 if ( *state_ptr != 0 )
822 chk[position + i] = i;
823 nxt[position + i] = *state_ptr;
826 if ( position + numecs > tblend )
827 tblend = position + numecs;
831 /* stack1 - save states with only one out-transition to be processed later
833 * If there's room for another state on the "one-transition" stack, the
834 * state is pushed onto it, to be processed later by mk1tbl. If there's
835 * no room, we process the sucker right now.
838 void stack1( statenum, sym, nextstate, deflink )
839 int statenum, sym, nextstate, deflink;
841 if ( onesp >= ONE_STACK_SIZE - 1 )
842 mk1tbl( statenum, sym, nextstate, deflink );
847 onestate[onesp] = statenum;
849 onenext[onesp] = nextstate;
850 onedef[onesp] = deflink;
855 /* tbldiff - compute differences between two state tables
857 * "state" is the state array which is to be extracted from the pr'th
858 * proto. "pr" is both the number of the proto we are extracting from
859 * and an index into the save area where we can find the proto's complete
860 * state table. Each entry in "state" which differs from the corresponding
861 * entry of "pr" will appear in "ext".
863 * Entries which are the same in both "state" and "pr" will be marked
864 * as transitions to "SAME_TRANS" in "ext". The total number of differences
865 * between "state" and "pr" is returned as function value. Note that this
866 * number is "numecs" minus the number of "SAME_TRANS" entries in "ext".
869 int tbldiff( state, pr, ext )
870 int state[], pr, ext[];
872 int i, *sp = state, *ep = ext, *protp;
875 protp = &protsave[numecs * (pr - 1)];
877 for ( i = numecs; i > 0; --i )
879 if ( *++protp == *++sp )