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326 lines
7.4 KiB
326 lines
7.4 KiB
/***** ltl2ba : rewrt.c *****/
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/* Written by Denis Oddoux, LIAFA, France */
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/* Copyright (c) 2001 Denis Oddoux */
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/* Modified by Paul Gastin, LSV, France */
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/* Copyright (c) 2007 Paul Gastin */
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/* */
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/* This program is free software; you can redistribute it and/or modify */
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/* it under the terms of the GNU General Public License as published by */
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/* the Free Software Foundation; either version 2 of the License, or */
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/* (at your option) any later version. */
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/* */
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/* This program is distributed in the hope that it will be useful, */
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/* but WITHOUT ANY WARRANTY; without even the implied warranty of */
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/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the */
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/* GNU General Public License for more details. */
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/* */
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/* You should have received a copy of the GNU General Public License */
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/* along with this program; if not, write to the Free Software */
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/* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA*/
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/* */
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/* Based on the translation algorithm by Gastin and Oddoux, */
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/* presented at the 13th International Conference on Computer Aided */
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/* Verification, CAV 2001, Paris, France. */
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/* Proceedings - LNCS 2102, pp. 53-65 */
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/* */
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/* Send bug-reports and/or questions to Paul Gastin */
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/* http://www.lsv.ens-cachan.fr/~gastin */
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/* */
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/* Some of the code in this file was taken from the Spin software */
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/* Written by Gerard J. Holzmann, Bell Laboratories, U.S.A. */
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#include "ltl2ba.h"
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extern int tl_verbose;
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static Node *can = ZN;
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Node *
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right_linked(Node *n)
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{
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if (!n) return n;
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if (n->ntyp == AND || n->ntyp == OR)
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while (n->lft && n->lft->ntyp == n->ntyp)
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{ Node *tmp = n->lft;
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n->lft = tmp->rgt;
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tmp->rgt = n;
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n = tmp;
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}
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n->lft = right_linked(n->lft);
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n->rgt = right_linked(n->rgt);
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return n;
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}
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Node *
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canonical(Node *n)
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{ Node *m; /* assumes input is right_linked */
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if (!n) return n;
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if (m = in_cache(n))
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return m;
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n->rgt = canonical(n->rgt);
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n->lft = canonical(n->lft);
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return cached(n);
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}
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Node *
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push_negation(Node *n)
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{ Node *m;
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Assert(n->ntyp == NOT, n->ntyp);
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switch (n->lft->ntyp) {
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case TRUE:
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releasenode(0, n->lft);
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n->lft = ZN;
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n->ntyp = FALSE;
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break;
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case FALSE:
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releasenode(0, n->lft);
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n->lft = ZN;
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n->ntyp = TRUE;
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break;
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case NOT:
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m = n->lft->lft;
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releasenode(0, n->lft);
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n->lft = ZN;
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releasenode(0, n);
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n = m;
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break;
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case V_OPER:
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n->ntyp = U_OPER;
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goto same;
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case U_OPER:
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n->ntyp = V_OPER;
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goto same;
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#ifdef NXT
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case NEXT:
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n->ntyp = NEXT;
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n->lft->ntyp = NOT;
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n->lft = push_negation(n->lft);
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break;
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#endif
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case AND:
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n->ntyp = OR;
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goto same;
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case OR:
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n->ntyp = AND;
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same: m = n->lft->rgt;
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n->lft->rgt = ZN;
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n->rgt = Not(m);
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n->lft->ntyp = NOT;
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m = n->lft;
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n->lft = push_negation(m);
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break;
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}
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return rewrite(n);
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}
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static void
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addcan(int tok, Node *n)
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{ Node *m, *prev = ZN;
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Node **ptr;
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Node *N;
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Symbol *s, *t; int cmp;
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if (!n) return;
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if (n->ntyp == tok)
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{ addcan(tok, n->rgt);
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addcan(tok, n->lft);
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return;
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}
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#if 0
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if ((tok == AND && n->ntyp == TRUE)
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|| (tok == OR && n->ntyp == FALSE))
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return;
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#endif
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N = dupnode(n);
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if (!can)
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{ can = N;
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return;
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}
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s = DoDump(N);
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if (can->ntyp != tok) /* only one element in list so far */
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{ ptr = &can;
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goto insert;
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}
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/* there are at least 2 elements in list */
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prev = ZN;
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for (m = can; m->ntyp == tok && m->rgt; prev = m, m = m->rgt)
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{ t = DoDump(m->lft);
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cmp = strcmp(s->name, t->name);
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if (cmp == 0) /* duplicate */
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return;
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if (cmp < 0)
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{ if (!prev)
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{ can = tl_nn(tok, N, can);
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return;
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} else
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{ ptr = &(prev->rgt);
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goto insert;
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} } }
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/* new entry goes at the end of the list */
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ptr = &(prev->rgt);
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insert:
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t = DoDump(*ptr);
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cmp = strcmp(s->name, t->name);
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if (cmp == 0) /* duplicate */
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return;
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if (cmp < 0)
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*ptr = tl_nn(tok, N, *ptr);
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else
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*ptr = tl_nn(tok, *ptr, N);
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}
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static void
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marknode(int tok, Node *m)
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{
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if (m->ntyp != tok)
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{ releasenode(0, m->rgt);
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m->rgt = ZN;
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}
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m->ntyp = -1;
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}
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Node *
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Canonical(Node *n)
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{ Node *m, *p, *k1, *k2, *prev, *dflt = ZN;
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int tok;
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if (!n) return n;
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tok = n->ntyp;
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if (tok != AND && tok != OR)
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return n;
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can = ZN;
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addcan(tok, n);
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#if 1
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Debug("\nA0: "); Dump(can);
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Debug("\nA1: "); Dump(n); Debug("\n");
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#endif
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releasenode(1, n);
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/* mark redundant nodes */
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if (tok == AND)
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{ for (m = can; m; m = (m->ntyp == AND) ? m->rgt : ZN)
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{ k1 = (m->ntyp == AND) ? m->lft : m;
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if (k1->ntyp == TRUE)
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{ marknode(AND, m);
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dflt = True;
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continue;
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}
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if (k1->ntyp == FALSE)
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{ releasenode(1, can);
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can = False;
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goto out;
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} }
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for (m = can; m; m = (m->ntyp == AND) ? m->rgt : ZN)
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for (p = can; p; p = (p->ntyp == AND) ? p->rgt : ZN)
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{ if (p == m
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|| p->ntyp == -1
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|| m->ntyp == -1)
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continue;
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k1 = (m->ntyp == AND) ? m->lft : m;
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k2 = (p->ntyp == AND) ? p->lft : p;
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if (isequal(k1, k2))
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{ marknode(AND, p);
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continue;
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}
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if (anywhere(OR, k1, k2))
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{ marknode(AND, p);
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continue;
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}
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if (k2->ntyp == U_OPER
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&& anywhere(AND, k2->rgt, can))
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{ marknode(AND, p);
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continue;
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} /* q && (p U q) = q */
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} }
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if (tok == OR)
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{ for (m = can; m; m = (m->ntyp == OR) ? m->rgt : ZN)
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{ k1 = (m->ntyp == OR) ? m->lft : m;
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if (k1->ntyp == FALSE)
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{ marknode(OR, m);
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dflt = False;
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continue;
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}
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if (k1->ntyp == TRUE)
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{ releasenode(1, can);
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can = True;
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goto out;
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} }
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for (m = can; m; m = (m->ntyp == OR) ? m->rgt : ZN)
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for (p = can; p; p = (p->ntyp == OR) ? p->rgt : ZN)
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{ if (p == m
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|| p->ntyp == -1
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|| m->ntyp == -1)
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continue;
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k1 = (m->ntyp == OR) ? m->lft : m;
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k2 = (p->ntyp == OR) ? p->lft : p;
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if (isequal(k1, k2))
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{ marknode(OR, p);
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continue;
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}
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if (anywhere(AND, k1, k2))
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{ marknode(OR, p);
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continue;
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}
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if (k2->ntyp == V_OPER
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&& k2->lft->ntyp == FALSE
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&& anywhere(AND, k2->rgt, can))
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{ marknode(OR, p);
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continue;
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} /* p || (F V p) = p */
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} }
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for (m = can, prev = ZN; m; ) /* remove marked nodes */
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{ if (m->ntyp == -1)
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{ k2 = m->rgt;
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releasenode(0, m);
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if (!prev)
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{ m = can = can->rgt;
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} else
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{ m = prev->rgt = k2;
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/* if deleted the last node in a chain */
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if (!prev->rgt && prev->lft
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&& (prev->ntyp == AND || prev->ntyp == OR))
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{ k1 = prev->lft;
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prev->ntyp = prev->lft->ntyp;
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prev->sym = prev->lft->sym;
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prev->rgt = prev->lft->rgt;
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prev->lft = prev->lft->lft;
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releasenode(0, k1);
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}
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}
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continue;
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}
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prev = m;
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m = m->rgt;
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}
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out:
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#if 1
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Debug("A2: "); Dump(can); Debug("\n");
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#endif
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if (!can)
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{ if (!dflt)
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fatal("cannot happen, Canonical", (char *) 0);
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return dflt;
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}
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return can;
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}
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