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NetBSD/usr.bin/lex/tblcmp.c

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/* tblcmp - table compression routines */
/*-
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Vern Paxson.
*
* The United States Government has rights in this work pursuant
* to contract no. DE-AC03-76SF00098 between the United States
* Department of Energy and the University of California.
*
* Redistribution and use in source and binary forms are permitted provided
* that: (1) source distributions retain this entire copyright notice and
* comment, and (2) distributions including binaries display the following
* acknowledgement: ``This product includes software developed by the
* University of California, Berkeley and its contributors'' in the
* documentation or other materials provided with the distribution and in
* all advertising materials mentioning features or use of this software.
* Neither the name of the University nor the names of its contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#ifndef lint
static char rcsid[] =
"@(#) $Header: /cvsroot/src/usr.bin/lex/Attic/tblcmp.c,v 1.2 1993/05/04 07:45:15 cgd Exp $ (LBL)";
#endif
#include "flexdef.h"
/* declarations for functions that have forward references */
void mkentry PROTO((register int*, int, int, int, int));
void mkprot PROTO((int[], int, int));
void mktemplate PROTO((int[], int, int));
void mv2front PROTO((int));
int tbldiff PROTO((int[], int, int[]));
/* bldtbl - build table entries for dfa state
*
* synopsis
* int state[numecs], statenum, totaltrans, comstate, comfreq;
* bldtbl( state, statenum, totaltrans, comstate, comfreq );
*
* State is the statenum'th dfa state. It is indexed by equivalence class and
* gives the number of the state to enter for a given equivalence class.
* totaltrans is the total number of transitions out of the state. Comstate
* is that state which is the destination of the most transitions out of State.
* Comfreq is how many transitions there are out of State to Comstate.
*
* A note on terminology:
* "protos" are transition tables which have a high probability of
* either being redundant (a state processed later will have an identical
* transition table) or nearly redundant (a state processed later will have
* many of the same out-transitions). A "most recently used" queue of
* protos is kept around with the hope that most states will find a proto
* which is similar enough to be usable, and therefore compacting the
* output tables.
* "templates" are a special type of proto. If a transition table is
* homogeneous or nearly homogeneous (all transitions go to the same
* destination) then the odds are good that future states will also go
* to the same destination state on basically the same character set.
* These homogeneous states are so common when dealing with large rule
* sets that they merit special attention. If the transition table were
* simply made into a proto, then (typically) each subsequent, similar
* state will differ from the proto for two out-transitions. One of these
* out-transitions will be that character on which the proto does not go
* to the common destination, and one will be that character on which the
* state does not go to the common destination. Templates, on the other
* hand, go to the common state on EVERY transition character, and therefore
* cost only one difference.
*/
void bldtbl( state, statenum, totaltrans, comstate, comfreq )
int state[], statenum, totaltrans, comstate, comfreq;
{
int extptr, extrct[2][CSIZE + 1];
int mindiff, minprot, i, d;
int checkcom;
/* If extptr is 0 then the first array of extrct holds the result of the
* "best difference" to date, which is those transitions which occur in
* "state" but not in the proto which, to date, has the fewest differences
* between itself and "state". If extptr is 1 then the second array of
* extrct hold the best difference. The two arrays are toggled
* between so that the best difference to date can be kept around and
* also a difference just created by checking against a candidate "best"
* proto.
*/
extptr = 0;
/* if the state has too few out-transitions, don't bother trying to
* compact its tables
*/
if ( (totaltrans * 100) < (numecs * PROTO_SIZE_PERCENTAGE) )
mkentry( state, numecs, statenum, JAMSTATE, totaltrans );
else
{
/* checkcom is true if we should only check "state" against
* protos which have the same "comstate" value
*/
checkcom = comfreq * 100 > totaltrans * CHECK_COM_PERCENTAGE;
minprot = firstprot;
mindiff = totaltrans;
if ( checkcom )
{
/* find first proto which has the same "comstate" */
for ( i = firstprot; i != NIL; i = protnext[i] )
if ( protcomst[i] == comstate )
{
minprot = i;
mindiff = tbldiff( state, minprot, extrct[extptr] );
break;
}
}
else
{
/* since we've decided that the most common destination out
* of "state" does not occur with a high enough frequency,
* we set the "comstate" to zero, assuring that if this state
* is entered into the proto list, it will not be considered
* a template.
*/
comstate = 0;
if ( firstprot != NIL )
{
minprot = firstprot;
mindiff = tbldiff( state, minprot, extrct[extptr] );
}
}
/* we now have the first interesting proto in "minprot". If
* it matches within the tolerances set for the first proto,
* we don't want to bother scanning the rest of the proto list
* to see if we have any other reasonable matches.
*/
if ( mindiff * 100 > totaltrans * FIRST_MATCH_DIFF_PERCENTAGE )
{ /* not a good enough match. Scan the rest of the protos */
for ( i = minprot; i != NIL; i = protnext[i] )
{
d = tbldiff( state, i, extrct[1 - extptr] );
if ( d < mindiff )
{
extptr = 1 - extptr;
mindiff = d;
minprot = i;
}
}
}
/* check if the proto we've decided on as our best bet is close
* enough to the state we want to match to be usable
*/
if ( mindiff * 100 > totaltrans * ACCEPTABLE_DIFF_PERCENTAGE )
{
/* no good. If the state is homogeneous enough, we make a
* template out of it. Otherwise, we make a proto.
*/
if ( comfreq * 100 >= totaltrans * TEMPLATE_SAME_PERCENTAGE )
mktemplate( state, statenum, comstate );
else
{
mkprot( state, statenum, comstate );
mkentry( state, numecs, statenum, JAMSTATE, totaltrans );
}
}
else
{ /* use the proto */
mkentry( extrct[extptr], numecs, statenum,
prottbl[minprot], mindiff );
/* if this state was sufficiently different from the proto
* we built it from, make it, too, a proto
*/
if ( mindiff * 100 >= totaltrans * NEW_PROTO_DIFF_PERCENTAGE )
mkprot( state, statenum, comstate );
/* since mkprot added a new proto to the proto queue, it's possible
* that "minprot" is no longer on the proto queue (if it happened
* to have been the last entry, it would have been bumped off).
* If it's not there, then the new proto took its physical place
* (though logically the new proto is at the beginning of the
* queue), so in that case the following call will do nothing.
*/
mv2front( minprot );
}
}
}
/* cmptmps - compress template table entries
*
* synopsis
* cmptmps();
*
* template tables are compressed by using the 'template equivalence
* classes', which are collections of transition character equivalence
* classes which always appear together in templates - really meta-equivalence
* classes. until this point, the tables for templates have been stored
* up at the top end of the nxt array; they will now be compressed and have
* table entries made for them.
*/
void cmptmps()
{
int tmpstorage[CSIZE + 1];
register int *tmp = tmpstorage, i, j;
int totaltrans, trans;
peakpairs = numtemps * numecs + tblend;
if ( usemecs )
{
/* create equivalence classes base on data gathered on template
* transitions
*/
nummecs = cre8ecs( tecfwd, tecbck, numecs );
}
else
nummecs = numecs;
if ( lastdfa + numtemps + 1 >= current_max_dfas )
increase_max_dfas();
/* loop through each template */
for ( i = 1; i <= numtemps; ++i )
{
totaltrans = 0; /* number of non-jam transitions out of this template */
for ( j = 1; j <= numecs; ++j )
{
trans = tnxt[numecs * i + j];
if ( usemecs )
{
/* the absolute value of tecbck is the meta-equivalence class
* of a given equivalence class, as set up by cre8ecs
*/
if ( tecbck[j] > 0 )
{
tmp[tecbck[j]] = trans;
if ( trans > 0 )
++totaltrans;
}
}
else
{
tmp[j] = trans;
if ( trans > 0 )
++totaltrans;
}
}
/* it is assumed (in a rather subtle way) in the skeleton that
* if we're using meta-equivalence classes, the def[] entry for
* all templates is the jam template, i.e., templates never default
* to other non-jam table entries (e.g., another template)
*/
/* leave room for the jam-state after the last real state */
mkentry( tmp, nummecs, lastdfa + i + 1, JAMSTATE, totaltrans );
}
}
/* expand_nxt_chk - expand the next check arrays */
void expand_nxt_chk()
{
register int old_max = current_max_xpairs;
current_max_xpairs += MAX_XPAIRS_INCREMENT;
++num_reallocs;
nxt = reallocate_integer_array( nxt, current_max_xpairs );
chk = reallocate_integer_array( chk, current_max_xpairs );
bzero( (char *) (chk + old_max),
MAX_XPAIRS_INCREMENT * sizeof( int ) / sizeof( char ) );
}
/* find_table_space - finds a space in the table for a state to be placed
*
* synopsis
* int *state, numtrans, block_start;
* int find_table_space();
*
* block_start = find_table_space( state, numtrans );
*
* State is the state to be added to the full speed transition table.
* Numtrans is the number of out-transitions for the state.
*
* find_table_space() returns the position of the start of the first block (in
* chk) able to accommodate the state
*
* In determining if a state will or will not fit, find_table_space() must take
* into account the fact that an end-of-buffer state will be added at [0],
* and an action number will be added in [-1].
*/
int find_table_space( state, numtrans )
int *state, numtrans;
{
/* firstfree is the position of the first possible occurrence of two
* consecutive unused records in the chk and nxt arrays
*/
register int i;
register int *state_ptr, *chk_ptr;
register int *ptr_to_last_entry_in_state;
/* if there are too many out-transitions, put the state at the end of
* nxt and chk
*/
if ( numtrans > MAX_XTIONS_FULL_INTERIOR_FIT )
{
/* if table is empty, return the first available spot in chk/nxt,
* which should be 1
*/
if ( tblend < 2 )
return ( 1 );
i = tblend - numecs; /* start searching for table space near the
* end of chk/nxt arrays
*/
}
else
i = firstfree; /* start searching for table space from the
* beginning (skipping only the elements
* which will definitely not hold the new
* state)
*/
while ( 1 ) /* loops until a space is found */
{
if ( i + numecs >= current_max_xpairs )
expand_nxt_chk();
/* loops until space for end-of-buffer and action number are found */
while ( 1 )
{
if ( chk[i - 1] == 0 ) /* check for action number space */
{
if ( chk[i] == 0 ) /* check for end-of-buffer space */
break;
else
i += 2; /* since i != 0, there is no use checking to
* see if (++i) - 1 == 0, because that's the
* same as i == 0, so we skip a space
*/
}
else
++i;
if ( i + numecs >= current_max_xpairs )
expand_nxt_chk();
}
/* if we started search from the beginning, store the new firstfree for
* the next call of find_table_space()
*/
if ( numtrans <= MAX_XTIONS_FULL_INTERIOR_FIT )
firstfree = i + 1;
/* check to see if all elements in chk (and therefore nxt) that are
* needed for the new state have not yet been taken
*/
state_ptr = &state[1];
ptr_to_last_entry_in_state = &chk[i + numecs + 1];
for ( chk_ptr = &chk[i + 1]; chk_ptr != ptr_to_last_entry_in_state;
++chk_ptr )
if ( *(state_ptr++) != 0 && *chk_ptr != 0 )
break;
if ( chk_ptr == ptr_to_last_entry_in_state )
return ( i );
else
++i;
}
}
/* inittbl - initialize transition tables
*
* synopsis
* inittbl();
*
* Initializes "firstfree" to be one beyond the end of the table. Initializes
* all "chk" entries to be zero. Note that templates are built in their
* own tbase/tdef tables. They are shifted down to be contiguous
* with the non-template entries during table generation.
*/
void inittbl()
{
register int i;
bzero( (char *) chk, current_max_xpairs * sizeof( int ) / sizeof( char ) );
tblend = 0;
firstfree = tblend + 1;
numtemps = 0;
if ( usemecs )
{
/* set up doubly-linked meta-equivalence classes
* these are sets of equivalence classes which all have identical
* transitions out of TEMPLATES
*/
tecbck[1] = NIL;
for ( i = 2; i <= numecs; ++i )
{
tecbck[i] = i - 1;
tecfwd[i - 1] = i;
}
tecfwd[numecs] = NIL;
}
}
/* mkdeftbl - make the default, "jam" table entries
*
* synopsis
* mkdeftbl();
*/
void mkdeftbl()
{
int i;
jamstate = lastdfa + 1;
++tblend; /* room for transition on end-of-buffer character */
if ( tblend + numecs >= current_max_xpairs )
expand_nxt_chk();
/* add in default end-of-buffer transition */
nxt[tblend] = end_of_buffer_state;
chk[tblend] = jamstate;
for ( i = 1; i <= numecs; ++i )
{
nxt[tblend + i] = 0;
chk[tblend + i] = jamstate;
}
jambase = tblend;
base[jamstate] = jambase;
def[jamstate] = 0;
tblend += numecs;
++numtemps;
}
/* mkentry - create base/def and nxt/chk entries for transition array
*
* synopsis
* int state[numchars + 1], numchars, statenum, deflink, totaltrans;
* mkentry( state, numchars, statenum, deflink, totaltrans );
*
* "state" is a transition array "numchars" characters in size, "statenum"
* is the offset to be used into the base/def tables, and "deflink" is the
* entry to put in the "def" table entry. If "deflink" is equal to
* "JAMSTATE", then no attempt will be made to fit zero entries of "state"
* (i.e., jam entries) into the table. It is assumed that by linking to
* "JAMSTATE" they will be taken care of. In any case, entries in "state"
* marking transitions to "SAME_TRANS" are treated as though they will be
* taken care of by whereever "deflink" points. "totaltrans" is the total
* number of transitions out of the state. If it is below a certain threshold,
* the tables are searched for an interior spot that will accommodate the
* state array.
*/
void mkentry( state, numchars, statenum, deflink, totaltrans )
register int *state;
int numchars, statenum, deflink, totaltrans;
{
register int minec, maxec, i, baseaddr;
int tblbase, tbllast;
if ( totaltrans == 0 )
{ /* there are no out-transitions */
if ( deflink == JAMSTATE )
base[statenum] = JAMSTATE;
else
base[statenum] = 0;
def[statenum] = deflink;
return;
}
for ( minec = 1; minec <= numchars; ++minec )
{
if ( state[minec] != SAME_TRANS )
if ( state[minec] != 0 || deflink != JAMSTATE )
break;
}
if ( totaltrans == 1 )
{
/* there's only one out-transition. Save it for later to fill
* in holes in the tables.
*/
stack1( statenum, minec, state[minec], deflink );
return;
}
for ( maxec = numchars; maxec > 0; --maxec )
{
if ( state[maxec] != SAME_TRANS )
if ( state[maxec] != 0 || deflink != JAMSTATE )
break;
}
/* Whether we try to fit the state table in the middle of the table
* entries we have already generated, or if we just take the state
* table at the end of the nxt/chk tables, we must make sure that we
* have a valid base address (i.e., non-negative). Note that not only are
* negative base addresses dangerous at run-time (because indexing the
* next array with one and a low-valued character might generate an
* array-out-of-bounds error message), but at compile-time negative
* base addresses denote TEMPLATES.
*/
/* find the first transition of state that we need to worry about. */
if ( totaltrans * 100 <= numchars * INTERIOR_FIT_PERCENTAGE )
{ /* attempt to squeeze it into the middle of the tabls */
baseaddr = firstfree;
while ( baseaddr < minec )
{
/* using baseaddr would result in a negative base address below
* find the next free slot
*/
for ( ++baseaddr; chk[baseaddr] != 0; ++baseaddr )
;
}
if ( baseaddr + maxec - minec + 1 >= current_max_xpairs )
expand_nxt_chk();
for ( i = minec; i <= maxec; ++i )
if ( state[i] != SAME_TRANS )
if ( state[i] != 0 || deflink != JAMSTATE )
if ( chk[baseaddr + i - minec] != 0 )
{ /* baseaddr unsuitable - find another */
for ( ++baseaddr;
baseaddr < current_max_xpairs &&
chk[baseaddr] != 0;
++baseaddr )
;
if ( baseaddr + maxec - minec + 1 >=
current_max_xpairs )
expand_nxt_chk();
/* reset the loop counter so we'll start all
* over again next time it's incremented
*/
i = minec - 1;
}
}
else
{
/* ensure that the base address we eventually generate is
* non-negative
*/
baseaddr = max( tblend + 1, minec );
}
tblbase = baseaddr - minec;
tbllast = tblbase + maxec;
if ( tbllast + 1 >= current_max_xpairs )
expand_nxt_chk();
base[statenum] = tblbase;
def[statenum] = deflink;
for ( i = minec; i <= maxec; ++i )
if ( state[i] != SAME_TRANS )
if ( state[i] != 0 || deflink != JAMSTATE )
{
nxt[tblbase + i] = state[i];
chk[tblbase + i] = statenum;
}
if ( baseaddr == firstfree )
/* find next free slot in tables */
for ( ++firstfree; chk[firstfree] != 0; ++firstfree )
;
tblend = max( tblend, tbllast );
}
/* mk1tbl - create table entries for a state (or state fragment) which
* has only one out-transition
*
* synopsis
* int state, sym, onenxt, onedef;
* mk1tbl( state, sym, onenxt, onedef );
*/
void mk1tbl( state, sym, onenxt, onedef )
int state, sym, onenxt, onedef;
{
if ( firstfree < sym )
firstfree = sym;
while ( chk[firstfree] != 0 )
if ( ++firstfree >= current_max_xpairs )
expand_nxt_chk();
base[state] = firstfree - sym;
def[state] = onedef;
chk[firstfree] = state;
nxt[firstfree] = onenxt;
if ( firstfree > tblend )
{
tblend = firstfree++;
if ( firstfree >= current_max_xpairs )
expand_nxt_chk();
}
}
/* mkprot - create new proto entry
*
* synopsis
* int state[], statenum, comstate;
* mkprot( state, statenum, comstate );
*/
void mkprot( state, statenum, comstate )
int state[], statenum, comstate;
{
int i, slot, tblbase;
if ( ++numprots >= MSP || numecs * numprots >= PROT_SAVE_SIZE )
{
/* gotta make room for the new proto by dropping last entry in
* the queue
*/
slot = lastprot;
lastprot = protprev[lastprot];
protnext[lastprot] = NIL;
}
else
slot = numprots;
protnext[slot] = firstprot;
if ( firstprot != NIL )
protprev[firstprot] = slot;
firstprot = slot;
prottbl[slot] = statenum;
protcomst[slot] = comstate;
/* copy state into save area so it can be compared with rapidly */
tblbase = numecs * (slot - 1);
for ( i = 1; i <= numecs; ++i )
protsave[tblbase + i] = state[i];
}
/* mktemplate - create a template entry based on a state, and connect the state
* to it
*
* synopsis
* int state[], statenum, comstate, totaltrans;
* mktemplate( state, statenum, comstate, totaltrans );
*/
void mktemplate( state, statenum, comstate )
int state[], statenum, comstate;
{
int i, numdiff, tmpbase, tmp[CSIZE + 1];
Char transset[CSIZE + 1];
int tsptr;
++numtemps;
tsptr = 0;
/* calculate where we will temporarily store the transition table
* of the template in the tnxt[] array. The final transition table
* gets created by cmptmps()
*/
tmpbase = numtemps * numecs;
if ( tmpbase + numecs >= current_max_template_xpairs )
{
current_max_template_xpairs += MAX_TEMPLATE_XPAIRS_INCREMENT;
++num_reallocs;
tnxt = reallocate_integer_array( tnxt, current_max_template_xpairs );
}
for ( i = 1; i <= numecs; ++i )
if ( state[i] == 0 )
tnxt[tmpbase + i] = 0;
else
{
transset[tsptr++] = i;
tnxt[tmpbase + i] = comstate;
}
if ( usemecs )
mkeccl( transset, tsptr, tecfwd, tecbck, numecs, 0 );
mkprot( tnxt + tmpbase, -numtemps, comstate );
/* we rely on the fact that mkprot adds things to the beginning
* of the proto queue
*/
numdiff = tbldiff( state, firstprot, tmp );
mkentry( tmp, numecs, statenum, -numtemps, numdiff );
}
/* mv2front - move proto queue element to front of queue
*
* synopsis
* int qelm;
* mv2front( qelm );
*/
void mv2front( qelm )
int qelm;
{
if ( firstprot != qelm )
{
if ( qelm == lastprot )
lastprot = protprev[lastprot];
protnext[protprev[qelm]] = protnext[qelm];
if ( protnext[qelm] != NIL )
protprev[protnext[qelm]] = protprev[qelm];
protprev[qelm] = NIL;
protnext[qelm] = firstprot;
protprev[firstprot] = qelm;
firstprot = qelm;
}
}
/* place_state - place a state into full speed transition table
*
* synopsis
* int *state, statenum, transnum;
* place_state( state, statenum, transnum );
*
* State is the statenum'th state. It is indexed by equivalence class and
* gives the number of the state to enter for a given equivalence class.
* Transnum is the number of out-transitions for the state.
*/
void place_state( state, statenum, transnum )
int *state, statenum, transnum;
{
register int i;
register int *state_ptr;
int position = find_table_space( state, transnum );
/* base is the table of start positions */
base[statenum] = position;
/* put in action number marker; this non-zero number makes sure that
* find_table_space() knows that this position in chk/nxt is taken
* and should not be used for another accepting number in another state
*/
chk[position - 1] = 1;
/* put in end-of-buffer marker; this is for the same purposes as above */
chk[position] = 1;
/* place the state into chk and nxt */
state_ptr = &state[1];
for ( i = 1; i <= numecs; ++i, ++state_ptr )
if ( *state_ptr != 0 )
{
chk[position + i] = i;
nxt[position + i] = *state_ptr;
}
if ( position + numecs > tblend )
tblend = position + numecs;
}
/* stack1 - save states with only one out-transition to be processed later
*
* synopsis
* int statenum, sym, nextstate, deflink;
* stack1( statenum, sym, nextstate, deflink );
*
* if there's room for another state one the "one-transition" stack, the
* state is pushed onto it, to be processed later by mk1tbl. If there's
* no room, we process the sucker right now.
*/
void stack1( statenum, sym, nextstate, deflink )
int statenum, sym, nextstate, deflink;
{
if ( onesp >= ONE_STACK_SIZE - 1 )
mk1tbl( statenum, sym, nextstate, deflink );
else
{
++onesp;
onestate[onesp] = statenum;
onesym[onesp] = sym;
onenext[onesp] = nextstate;
onedef[onesp] = deflink;
}
}
/* tbldiff - compute differences between two state tables
*
* synopsis
* int state[], pr, ext[];
* int tbldiff, numdifferences;
* numdifferences = tbldiff( state, pr, ext )
*
* "state" is the state array which is to be extracted from the pr'th
* proto. "pr" is both the number of the proto we are extracting from
* and an index into the save area where we can find the proto's complete
* state table. Each entry in "state" which differs from the corresponding
* entry of "pr" will appear in "ext".
* Entries which are the same in both "state" and "pr" will be marked
* as transitions to "SAME_TRANS" in "ext". The total number of differences
* between "state" and "pr" is returned as function value. Note that this
* number is "numecs" minus the number of "SAME_TRANS" entries in "ext".
*/
int tbldiff( state, pr, ext )
int state[], pr, ext[];
{
register int i, *sp = state, *ep = ext, *protp;
register int numdiff = 0;
protp = &protsave[numecs * (pr - 1)];
for ( i = numecs; i > 0; --i )
{
if ( *++protp == *++sp )
*++ep = SAME_TRANS;
else
{
*++ep = *sp;
++numdiff;
}
}
return ( numdiff );
}
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